Biosecurity and Invasive Species

F1000 January review: Science can be practical!

2012-01-19T16:31:00.000+11:00

Its always nice to find an example of where a great scientific theory can be tested and prove useful! In this case, ideas about how timing of watering regimes can give a phenological advantage to invaders but could then also be manipulated to give a disadvantage and so suppress invading populations. Ideas like this have existed in weed control in agriculture for a long time, but its interesting to see this kind of thinking emerging in a new context.

Wainwright CE, Wolkovich EM, Cleland EE (2011) Seasonal priority effects: implications for invasion and restoration in a semi-arid system. J App Ecol. 49:234-41

Our review:

Parry H, Lonsdale M: 2012. http://f1000.com/13480958

This is a good example of hypothesis-driven research in invasion ecology. A concept of phenologically driven seasonal ‘priority advantage’ is introduced, which can be used to explain the success of an invasive species. Having shown that the concept is applicable to exotic annual grasses in California, the authors go a step further and show how an understanding of phenology can be a powerful weapon in restoring invaded ecosystems.

The paper provides experimental evidence that earlier establishment of exotic seedlings under a normal watering regime gives them a ‘priority advantage’. The ‘priority advantage’ is turned into a ‘priority disadvantage’ for the invader when an early season watering regime is introduced. This stimulates early germination of the invasive before true growing season rains, resulting in reduced survival throughout the season as the early seedlings die and a depleted seed bank for later germination. The possibility that this can be used to manage the invader is posed – a suggestion foreshadowed by an older literature for agronomic weeds on the manipulation of the seed bank [1]. However, the study does not isolate the direct effects of phenology and environmental stress from other factors, such as the presence of herbivores; the authors argue that the herbivores simply act to augment the stress impacts of the early season watering strategy and are simply a component of the ‘priority disadvantage’. To implement such a management strategy for vegetation in reality, not only the water regime but also the presence of herbivores should likely be optimised.

[1] Egley GH, Rev Weed Sci 1986, 2:67-89

Mutant killer fungus

2012-01-04T10:24:00.000+11:00

Our latest review is of a study that reveals something close to science fiction in the interactions between a bark beetle, a fungus and the host plant. It is a very good paper that presents a well executed study, that includes multiple methods to consider the question:

Do novel genotypes drive the success of an invasive bark beetle-fungus complex? Implications for potential reinvasion.

Lu M, Wingfield MJ, Gillette N and Sun JH, Ecology. 2011 92(11):2013-9

Our Review: Parry H, Lonsdale M: 2011. F1000.com/13416967

This fascinating paper explores the emergence of a mutant, killer fungus as a result of an unholy alliance between the fungus, its beetle vector, and its host plant. It is important for invasion ecologists because it emphasises the role of novel genotypes in invasion success and it does so in the context of a three-way interspecific interaction.

The paper describes a feedback loop whereby introduced bark beetles are attracted to a chemical given off by fungus-infected pines, spreading a novel fungal genotype that suppresses the growth of competing fungi and increases the release of the attractant, so attracting yet more beetles to increase the dispersal of the novel genotype. The results from the study show that the novel genotype has emerged post-invasion. The paper contains a nice mix of biotechnology, pathology and insect behavioural experiments to tease out the interaction.

The implications of the findings are that a novel genotype that is more pathogenic to pine trees has evolved in the introduced range (China) and now poses a threat to the native range (North America).

Biosecurity research efforts will be well funded in Australia

2011-11-22T16:06:00.001+11:00

News just out - the Plant Biosecurity Cooperative Research Centre (CRC) has won its rebid, second time lucky! Here is a link to the previous, related, CRC for National Plant Biosecurity for whom I spent 2 years working as a post-doc. Alongside CSIRO's new Biosecurity Flagship, funding support for research into Biosecurity in Australia has never been stronger, exciting times.

A meta-analysis of the impacts of alien plants

2011-11-17T10:33:00.000+11:00

Our latest review is of a meta-analysis that examines a wide range of studies from across the globe (including invasive animals, as well as plants) to try and identify some general impacts invasive species have on species, communities and ecosystems.

Vilà, M., Espinar, J. L., Hejda, M., Hulme, P. E., Jarošík, V., Maron, J. L., Pergl, J., Schaffner, U., Sun, Y. and Pyšek, P. (2011), Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems. Ecology Letters, 14: 702–708. doi: 10.1111/j.1461-0248.2011.01628.x

Our Review: Parry H, Lonsdale M: 2011. F1000.com/13365971

This comprehensive meta-analysis of over 500 articles illuminates some key future research directions for the ecology of alien plant introductions. The authors draw some conclusions on the general relative impacts of alien plants on ecosystems. These impacts range from species, through community, up to ecosystem-level, including changes in nutrient levels and cycling.

Over the last ten years, since Parker et al. published a review that sought to understand the general impacts of invaders on ecosystems [1], there has been an explosion of literature on this subject. This article provides a well executed and timely summary of a wide range of studies, drawing some conclusions on the relative general ecosystem impacts of both non-native plants and animals. These conclusions primarily indicate important directions for future research in plant invasions. This includes a need to: (a) investigate further 'island' effects and the importance of scale in measuring impact; (b) consider sampling effects when exploring relationships between the impacts of alien species on native plant diversity and production; and (c) explore more thoroughly the direct and indirect ecosystem impacts of alien species.

Despite equal effort in surveying the literature on animal species and communities, one shortcoming is that this study doesn’t conclude similar future directions for animal research. Some interesting perspectives on the bias in the literature are also gained by such a study. Here, we see that there is a bias in plant research towards trees and shrubs, as well as to certain regions such as Australia. We cannot draw on a long history of research in this area as the studies are nearly all from the last ten years.

References:
[1] Parker et al. Biol Invasions 1999, 1:3-19

What is this blog about?

2011-11-07T17:20:00.001+11:00

Well, I created a word cloud using Wordle to tell you!
(if you click the picture below you will see it more clearly)

A global experiment in biogeography

2011-11-07T10:23:00.001+11:00

I am continuing to assist Dr Lonsdale and review for F1000 after all! The last few months there seems to have been an absolute flurry of decent articles on invasion ecology, so we have carefully waded through to try and pick out some gems. This review is really a review of a special issue rather than a single article, with an entire issue of Diversity and Distributions dedicated to that global wanderer, the Acacia. This showcases a diverse range of excellent studies on the acacia from across the globe.

Human-mediated introductions of Australian acacias – a global experiment in biogeography.
Richardson, D. M., Carruthers, J., Hui, C., Impson, F. A. C., Miller, J. T., Robertson, M. P., Rouget, M., Le Roux, J. J. and Wilson, J. R. U. (2011) Diversity and Distributions, 17: 771–787.
DOI: 10.1111/j.1472-4642.2011.00824.x

Our review: Parry H, Lonsdale M: 2011. F1000.com/13357278

This is the leading article for a special issue of ‘Diversity and Distributions’ that focuses on the global movement of Australian acacia species and their invasiveness. The paper is important in establishing the case that acacias are a powerful model for testing some fundamental ideas in invasion ecology, which subsequent articles in the issue go on to do.

The paper argues that acacias are an excellent model group to examine the multiple drivers of species introductions. The authors present an overview of Australian acacia species and their invasiveness, as well as map the global invasion history of acacias onto the unified framework for biological invasions [1]. This paper also serves as an introduction to an interesting special issue, with highlights that include an analysis of the native ‘macroecological’ distribution of acacias in relation to their global invasiveness [2]. The latter article concludes that there is a (possibly human) bias in introductions for acacias with large ranges and high rates of population increase in their native range. The following articles within the journal then focus on predicting the invasiveness of acacias based on climatic envelopes, life history and human use [3], as well as mechanistic niche modelling to project future distributions under climate change scenarios [4]. Another highlight is an article that uses a phylogenetically corrected dataset to explore the role of genome size and functional traits in invasiveness [5]. Overall, this special issue highlights the opportunity that acacias and other woody plants [6] provide us to address some general ecological questions about invasion ecology.

[1] Blackburn et al. Trends Ecol Evol 2011, 26:333-9
[2] Hui et al. Divers Distrib 2011, 17:872-83
[3] Castro-Díez et al. Divers Distrib 2011, 17:934-45
[4] Webber et al. Divers Distrib 2011, 17:978-1000
[5] Gallagher et al. Divers Distrib 2011, 17:884-97.
[6] Richardson and Rejmánek, Divers Distrib 2011, 17:788-809

Post-docs ahoy!

2011-11-02T09:58:00.001+11:00

I received this advert for some post-doc positions that have come up in New Zealand that may be of interest:

Three Post Doctoral fellowships are now available in the Bio-Protection Research Centre (www.bioprotection.org.nz) working with Profs. Phil Hulme and Richard Duncan. The Post Doctoral fellows will join an active research group focused on the ecology of plant invasions, which has strong international linkages and a focus on high quality scientific publications. The Post Doctoral fellow will undertake independent research as well as contributing to wider research through interactions with staff and postgraduate students in the plant invasions group. Funding commences 1 February 2012.

The three fellowships available are:

1. Post Doctoral Fellowship (2 years extendable to 3) working on the project entitled ‘Cereal Killers: Integrating global data to predict the future risks of arable weeds’ under the supervision of Prof. Phil Hulme at Lincoln University, Canterbury, NZ (Vacancy Number 11-73)

2. Post Doctoral Fellowship (2 years extendable to 3) working on the project entitled ‘Rates of pathogen accumulation in introduced host plants’ under the supervision of Prof. Richard Duncan at Lincoln University, Canterbury, NZ (Vacancy Number 11-74)

3. Post Doctoral Fellowship (1 year only) working on the project entitled ‘Climate change and species responses at multiple scales’ under the supervision of Profs. Phil Hulme and Richard Duncan at Lincoln University, Canterbury, NZ (Vacancy Number 11-75)

For information about the three Post Doctoral fellowships, which are to be hosted at Lincoln University, please visit the Lincoln University website (http://www.lincoln.ac.nz/About-Lincoln-University/Job-vacancies/Academic-vacancies/) or contact the Human Resources Section quoting the vacancy number on phone +64 3 325 3687, fax +64 3 325 3870, email: jobs@lincoln.ac.nz. Post Doctoral Fellowship applications must be received by 11.00pm (NZ time) on Sunday, 20 November 2011.

A round-up of the last month or so

2011-09-26T12:47:00.002+10:00

After taking some time out to visit the UK to see my folks I'm back in action! There seems to have been quite a lot of interesting publications in the invasion ecology space over the last couple of months, so as I am trawling through to select for our next F1000 review I thought I would share my shortlist with you!

- Biological invasions in rapidly urbanizing areas: a case study of Beijing, China (Biodiversity and Conservation): this is interesting as it seems pretty novel to give a baseline of invasives for a city like Beijing and is well executed – implications for many other cities in the ‘developing’ world and simply highlights the research needs following such a comprehensive baseline study quite well ((i) estimates of species frequency in each district; (ii) identification of the historical process of invasions within the municipality; (iii) identification of the most aggressive invaders; and (iv) estimates of the economic and environmental impacts of the introduced species. http://www.springerlink.com/content/vq847t82k48u28j6/

- Diversity and Distributions Special Issue: Human-mediated introductions of Australian acacias - a global experiment in biogeography I've not gone through this too thoroughly yet, but interesting it has got so much attention to warrant a special issue - http://onlinelibrary.wiley.com/doi/10.1111/ddi.2011.17.issue-5/issuetoc one of the papers is Trees and shrubs as invasive alien species – a global review

- Strong response of an invasive plant species (Centaurea solstitialis L.) to global environmental changes (Ecological Applications) – simply a nice study as it looks at multiple and combined environmental changes (temperatures, CO2, fire etc) and their impacts on an invasive, whereas most studies only look at one aspect of future climates. http://www.esajournals.org/doi/pdf/10.1890/11-0111.1

- Remote analysis of biological invasion and the impact of enemy release (Ecological Applications) – as summarized at the end of the abstract, this is interesting because: These findings demonstrate that enemy release from generalist herbivores can facilitate exotic success and suggest a plausible mechanism by which invasion occurred. They also show how novel remote-sensing technology can be integrated with conservation and management to help address exotic plant invasions. http://www.esajournals.org/doi/pdf/10.1890/10-0859.1

- Propagule pressure hypothesis not supported by an 80-year experiment on woody species invasion (Oikos) – one of those long term data rich studies that also challenges a theory about invasion ecology. http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0706.2011.19504.x/abstract

- Invasive plants do not display greater phenotypic plasticity than their native or non-invasive counterparts: a meta-analysis (Oikos) – the magic word ‘meta-analysis’ and like above also challenges a theory (though we have looked at studies challenging this theory before and it often depends how its looked at...) http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0706.2010.19114.x/abstract

- Invasives: Sea of Data Still to Come (Science) This is a v short letter but it highlights some issues surrounding marine invasives and the lack of knowledge about dispersal ecology. The other letter on the page is also about invasives on this page just relates to the ongoing controversial debate about ‘embracing invasives’… http://www.sciencemag.org/content/333/6045/937.3.full.pdf

Analyzing the Social Factors That Influence Willingness to Pay for Invasive Alien Species Management Under Two Different Strategies: Eradication and Prevention (Environmental Management) – an article that is a bit obscure but interesting topic – not often is the social context of invasives well addressed but its very important determinant on how they are managed. http://www.springerlink.com/content/m70762l8541p5166/

Get informed on the climate debate

2011-08-03T14:08:00.000+10:00

Want to put up a good debate next time you are faced with a Climate Change denier, like this Australian example in blog-land? Get informed on the scientific facts by leading scientists at CSIRO's informative workshop coming up on Saturday 20th August.

A Warming earth: What is the cost of doing nothing?

Saturday 20 August 9am – 5.30pm
CSIRO Discovery Centre, Canberra

Are you confused by the global warming debate? What is the actual scientific evidence behind global warming? What are the implications and challenges? Can we afford to do nothing? These questions and more will be explored and discussed in this interactive one-day workshop hosted by the ACT branch of the Australian Meteorological and Oceanographic Society (AMOS) and CSIRO Discovery Centre.

Species relocation under climate change - a hot topic!

2011-07-28T15:32:00.000+10:00

A flurry of recent publications indicate to me that the idea of assisted colonization is a hot topic. Another contribution in this area is from a CSIRO collaboration with UQ and Melbourne Uni, in the new journal 'Nature Climate Change':

Optimal timing for managed relocation of species faced with climate change
Eve McDonald-Madden, Michael C. Runge, Hugh P. Possingham and Tara G. Martin (2011) Nature Climate Change 1 261–265

This new journal is likely to be highly influential and perhaps also this paper. It provides a decision framework to enable relocation of species in a timely and proactive fashion under the threat of climate change (or perhaps more likely, human population pressure). The approach is largely based on theoretical carrying capacities for the source and new region and projections on how they will change over time, with relocation aiming to optimise population size. The authors try to incorporate uncertainty into their decisions, making the observation that ' There are two key components of climate change that are particularly challenging: management in the face of system changes; and management in the face of uncertainty surrounding these changes.' It is a very 'theoretical' paper - I would like to see the approach they advocate applied to a practical example. Maybe that will be a follow-up publication!

Figure 1: Carrying capacities in the source (K_S) and destination (K_D) are shown with thick solid and dashed lines respectively; the population size, N, is shown with a thin solid line. The population size represents the state of the system by which decisions are specified. Note, N can decline with K_S or increase towards K_S, depending on the starting population size. The premise of managed relocation is that the suitability of the source habitat will decline with climate change and a destination habitat will become suitable. c_S and c_D represent the times at which half the suitable habitat in the source and destination populations are expected to be lost. The demographic cost of moving a population is expressed as the relocation survival rate, ϕ. The thin dashed line represents population change after relocation based on ϕ.

Assisted colonization

2011-07-21T09:58:00.000+10:00

Our latest review for F1000! It is perhaps my last, as I am soon to take up a post at CSIRO in Brisbane, so I won't be able to work closely with Mark Lonsdale on this anymore, but we shall see. It has been very interesting searching the literature each month for worthy papers to review for F1000. Now I am in the habitat I will certainly continue writing this blog!

Assisted colonization: integrating conservation strategies in the face of climate change.

Loss SR, Terwilliger LA, Peterson AC 2011 Biol Conservation 144: 92-100

DOI 10.1016/j.biocon.2010.11.016

Reviewed at Parry H, Lonsdale M: 2011. F1000.com/10103966

As global change accelerates and with it species extinctions, it seems that new measures may be needed in conservation practice. One such measure -- a controversial one -- is that of ‘assisted colonization’. Loss et al. review the potential means to implement such an approach. They feel that there may be some scope for careful use of assisted colonization in conjunction with other landscape-scale conservation measures.

Species that are in small, isolated, non-mobile or low-dispersing populations situated in fragmented landscapes are characterised as species that are threatened by the potential impacts of climate change. Assisted colonization is suggested as a useful conservation strategy for such species, but only when combined in an ‘integrated approach’. Loss et al. conclude that short-distance translocations are less likely to result in biological invasions, that a consideration of the full range of a species rather than only peripheral populations should be made and that assisted colonization is best combined with other approaches, like habitat corridors. They liken assisted colonization to ‘integrated pest management’, where a strategy of employing a range of control measures is likely to produce the most effective long-term outcome and minimise the risk of damage to the environment.

Some authors have argued strongly against ideas of assisted colonization, likening it to ‘ecological roulette’ (Ricciardi and Simberloff, TREE 24, 2009), which may, for example, result in the species becoming invasive in its new range. In recognition of this, Loss et al. argue that assisted colonization must be preceded by a thorough risk assessment. However, the reliability of frameworks for risk assessments of introduced species is questionable ( Groves et al. Chapters 3 and 5 in: “Weed Risk Assessment.” Collingwood: CSIRO Publishing, 2001). In addition, it is not clear to us that the integrated approach Loss et al. advocate will reduce uncertainty. Rather, by introducing multiple processes that may interact unpredictably, it could compound it.

Overall, this article is a notable manifestation of the controversy in the literature on this strategy (see also Vilà and Hulme, TREE 2011, Jul 13 (Epub ahead of print) and Thomas CD, TREE 2011, 26).

Climate change - so what?

2011-07-08T14:13:00.003+10:00

An interesting collection of papers has recently been published in Proceedings of the Royal Society A (London) answering the questions of will the world get over 4 degrees C warmer and so what if it does...

Four degrees and beyond: the potential for a global temperature increase of four degrees and its implications

It is based around papers given at a conference in 2009 that asked '(i) how probable a warming of four degrees or higher might be, (ii) what the consequences of such a warming might be for ecosystems and society, (iii) how to adapt to such large changes, and (iv) how to keep the risk of high-end climate change as low as possible.'

Here are some views from a group of Aussie climate scientists!

Science at the Shine Dome

2011-05-19T13:40:00.001+10:00

A couple of weeks ago I was really honored to be nominated for sponsorship to attend Science at the Shine Dome, as an Early Career Researcher. Science at the Shine Dome is the annual meeting of the Australian Academy of Sciences (the Australian equivalent of the Royal Academy in the UK). Hearing fellows of the academy and awardees give fantastic talks about their research was very inspiring and their enthusiasm for science was infectious.

Here is a photo of me (in a very obvious green jumper!) - Firstly with the other 'travel awardees' and then with all the Early Career researchers in front of the Shine Dome. Photo credit and copyright to Mark Graham photography.

The symposium on Population Challenges to Sustainability was a very interesting one, as there are of course many angles on that complex debate. The programme for the day was really well thought out and was not all ‘doom’ at all, although there were quite a few sobering statistics. There was a thought provoking talk on urban design for higher density living as a viable way to cope with increasing populations in Australia and to make our cities more ‘efficient’, although this would obviously imply a lifestyle change for many Australians. There were also many suggestions on how we might measure impacts and manage population increase in Australia, including Tim Flannery’s suggestion to set up an advisory board to evaluate potential impacts against various criteria to set population ‘limits’. A number of talks also questioned the emphasis on justifying population increase to increase total GDP, when GDP per capita and other indices may be a better measure of ‘wealth’ – and there appears to be little influence of population increase on GDP per capita. The question was also raised as to whether economists can’t begin to think about how a contracting economy may be viable rather than always focusing on increasing GDP. Issues of health and education were also covered, including a talk by Marie Stopes charity which appears to have been successful in some developing countries to reduce population increase through giving women greater access to contraceptives and thus freedom of choice.

CSIRO was well represented at the symposium with talks on population pressure on water resources and agriculture (food security), highlighting the challenges of climate change as well as increasing populations. I was also pleased to meet Professor Michael Barber at the dinner, who is a fellow of the academy and former CSIRO executive.

Here I am (on the right) dressed up for the wonderful black-tie dinner at the Museum of Australia (photo copyright: Mark Graham Photography). The speaker at the dinner was Professor Robert, Lord May of Oxford, who was very entertaining but also made some profound comments in relation to the theme of sustainability and population increase.

May review for F1000

2011-05-19T09:50:00.002+10:00

At last, a paper about cane toads! Well, not quite, but this study on amphibians is an interesting one, as the literature on establishment success is somewhat swamped by plant studies. Therefore, this study, which uses a meta-analysis of amphibian populations across the globe to examine Darwin's Naturalization hypothesis, is interesting and refreshing.

Establishment success of introduced amphibians increases in the presence of congeneric species.

R Tingley, BL Phillips, R Shine Am Nat 2011 Mar 177 3:382-8 DOI 10.1086/658342

Our Review: Parry H, Lonsdale M: 2011. F1000.com/10431957

When it comes to testing ecological theories of invasion processes, plants have often been the organism of choice. So, to see amphibians being used to test Darwin’s naturalization hypothesis, as in this paper, is exciting.

Darwin's naturalization hypothesis predicts that when species are introduced to a new range, those with fewer close relatives in the region would tend to have greater success. The results of the meta-analysis presented here contradict this. They indicate that the probability of successful amphibian establishment increases when congeneric species are present at the introduced location. It is argued that the underlying reason for this is the consequent pre-adaption of introduced species to climatic and other abiotic factors.

This neat little paper presents the results in a concise manner, incorporating important details of the key factors to account for in such an analysis, such as including a measure of ‘propagule pressure’ and identifying confounding species, event and location characteristics, which serves as a guide for similar analyses in the future.

It should be noted that another recent paper, based on laboratory experiments with bacteria, supports Darwin's hypothesis {1}. Likewise, there have long-been opposing conclusions reached when testing this hypothesis on flora: a recent study also supports Darwin’s hypothesis {2} whereas another refutes it {3}. In some other cases, contradictions between studies result from a focus on different stages in the invasion process: the ability of a species to invade a region versus the ability of a species to naturalize {2}.

References:
{1} Jiang et al. Am Nat 2010, 175:415-23
{2} Schaefer et al. Ecol Lett 2011, 14:389-96
{3} Duncan and Williams, Nature 2002, 417:608-9

I also came across an article about this paper on the web, which can be viewed here: American Society of Naturalists. An intriguing comment at the bottom - someone has tried to find what Darwin actually says in the Origin of Species that can be termed his 'Naturalization hypothesis'. I haven't read this book myself - perhaps I should as an ecologist! - but it is an interesting question, where and how does Darwin state this hypothesis? Sometimes ideas can gain a life of their own in the academic literature, it would certainly be interesting to know the precise source and statement of this hypothesis.

A popular review

2011-05-09T10:51:00.001+10:00

I was really pleased to be told by F1000 that our April review has proved very popular on their site, it was in the top 5% in terms of user accesses for 2 weeks following its publication. This highlights the importance to the scientific community of the research question 'What are the determinants of success in invasive species?'

Mapping threatened ecosystems in Australia

2011-04-27T09:51:00.002+10:00

This is an interesting map, recently published as part of the Bioscience article 'The Spatial Distribution of Threats to Species in Australia', Evans et al., BioScience, 61(4):281-289. 2011.

Figure 3: The distribution of the predominant threats to biodiversity across Australia. The “predominant threat” is the threat affecting the greatest number of species in each subcatchment. Where two or more threats affect an equivalent number of species, we consider there to be no predominant threat occurring in these subcatchments, displayed here in shades of gray.
Darker colors indicate a larger overall number of threats occurring in the subcatchment. White indicates areas where no threatened species occur.

This is quite a novel way to highlight the range of threats to Australian ecosystems, putting them in a spatial context. The article argues that the use of such a spatial and visual analysis will aid mitigation efforts and help identify location-specific threats.

However, I think there is a danger with the above map that it could be mis-read, i.e. 'no predominant threat' could be read as 'no threat', whereas it actually signifies that there are threats but no particular class of threat dominates. This mistake can be made more easily because the 'no threat' value is missing from the key - I presume this to be the white areas. Also, where there are several threats from multiple sources this map masks out threats which don't dominate but which may be significant (though more detail is given in the paper and multiple maps - which are perhaps more useful). Really, I'm not too sure how useful this combined map really is - it seems to have more potential to mis-lead than to inform. As as geographer, I often find the lack of basic cartography in such maps (full legend, north arrow, scale?!) to be frustrating.

Mother Nature's Melting Pot?!

2011-04-18T11:18:00.001+10:00

The latest 'pro-invasive' article I've come across was from reading this post on my colleague Shuang's blog, linking to an article in the New York Times "Mother Nature's Melting Pot". This article makes a pretty outrageous link (imho) between alien plant and animal species and human immigrants. Hang on, Homo sapiens are a single species last time I checked, so perhaps its not too surprising we can live happily alongside one another - though then again, perhaps we could take a few lessons from ecology in that respect!

While the vanguard of the anti-immigrant crusade is found among the likes of the Minutemen and the Tea Party, the native species movement is led by environmentalists, conservationists and gardeners. Despite cultural and political differences, both are motivated — in Margaret Thatcher’s infamous phrase — by the fear of being swamped by aliens.

April review for F1000

2011-04-14T11:11:00.001+10:00

This month we have found some good papers. We decided to first review a paper that is very much in Mark's field of interest - what factors determine species invasion success. This paper provides some evidence as to whether greater phenotypic plasticity of invasives is important.

AM Davidson, M Jennions, AB Nicotra (2011) Do invasive species show higher phenotypic plasticity than native species and, if so, is it adaptive? A meta-analysis. Ecol Lett 2011 Apr 14 4:419-31
DOI 10.1111/j.1461-0248.2011.01596.x

Our Review: Parry H, Lonsdale M: 2011. F1000.com/9268957
Another review of this paper is also available at the above link, by Hao Wang and Mark Lewis of the University of Alberta, Canada.

What are the determinants of success in invasive species? Tonnes of wood pulp have been expended in proposing predictors of invasion success, such as morphology, taxonomic relatedness and propagule pressure, which might help us to screen out dangerous species before it is too late. One hypothesis put forward is that the greater phenotypic plasticity of invaders, compared with natives, determines the success of invasive species (1}. This study provides evidence to support this hypothesis through a comparative analysis, but fails to find support for the related hypothesis, that such phenotypic plasticity results in a fitness advantage for invasives {1}. Using a meta-analysis of 75 invasive and non-invasive species pairs, the study finds that invasive species show greater phenotypic plasticity than their non-invasive congeners. Strangely, however, this greater plasticity is only rarely associated with greater fitness. In fact, the study finds that, when resources are limiting, non-invasive species respond better.

Where does this leave us? The study has shown the greater plasticity of invasives compared with natives. However, the study could not relate this to fitness, and so concludes that the benefits of plasticity to the invader will be context sensitive. This latter conclusion highlights the difficulty of predicting invasion success on the basis of biological attributes alone - it is the interaction of those attributes with the environment that will determine invasion success.

References:
{1} Richards et al. Ecol Lett 2006, 9:981-93

March Review for F1000

2011-03-31T17:57:00.001+11:00

This month we found something addressing the ongoing debate about the relationship between invasibility and diversity of native species; however, this study takes a new angle and looks at the relationship through time rather than across space. Our biggest disappointment with this paper was that it makes a large assumption that abundance of a single species = diversity, which is not necessarily the case. Therefore to really prove the conclusions of this study about this general hypothesis, the authors need to either test this assumption thoroughly or undertake a study focusing directly on invasive species diversity in relation to native diversity.

Our Review:
Parry H, Lonsdale M: 2011. F1000.com/9274956

This is the first study of note that attempts to examine the relationship between invasibility and native species diversity across temporal scales. The diversity-invasibility relationship has intrigued researchers interested in invasion ecology because a paradox has arisen, as the relationship appears to flip at different spatial scales.

Elton {1} first proposed that a high richness of native species protects sites against invasion, where fewer invasive species are able to colonise areas with high native diversity, due to a lack of available resources. At small spatial scales, a negative relationship between native and exotic diversity has been found, in many studies, including Elton's, to support this hypothesis. However, at large spatial scales, there has been less agreement and the inverse has proved true {2}. Clarke and Johnston refer to this as the 'invasion paradox'. Although this relationship has been examined in detail in many studies, at multiple spatial scales, there have been very few, if any, studies of how this relationship might change over time.

This study goes some way to examining how this relationship might vary over time, as a possible explanation of the invasion paradox. The study shows that the diversity-invasibility relationship can vary through time when mediated by disturbance. It is found that disturbance favours colonization, but not persistence, of the invader; thus, the inverse relationship found between native diversity and disturbance indicates that diversity may favour persistence of the invader, but not colonization.

The authors make a key assumption in their experiment; that the abundance of a single invader species is a surrogate for invader diversity - this needs further testing.

NB – I am listed as an author on ref {2}.

References:
{1} Elton CS, "The ecology of invasions by animals and plants." Methuen and Co Ltd: London, 1958 [ISBN:978-0412114304].
{2} Lonsdale WM, Ecology 1999, 80:1522-36 [DOI:10.1890/0012-9658(1999)080[1522:GPOPIA]2.0.CO;2].

Competing interests: None declared

Embracing Invasives

2011-03-30T14:08:00.002+11:00

Embracing Invasives is the title of a recent article in Science. So, it seems the pro-invasive band-wagon is growing! In this article, Science take the case of the Galapagos - viewed by many as the world's most pristine environment - and highlight that scientists trying to eradicate invasives on these islands are now admitting defeat, ready to 'embrace' the presence of alien species. Given the damage invasives such as Guava and Blackberries are known to do to this environment, I do wonder what the real reasons might be for giving up the fight? I think there is more to this story than given in this article. Maybe I am cynical, but I would suspect budget cuts from struggling world economies that support such initiatives are to blame, rather than a scientific turnaround, which they are now trying to justify. I'm afraid I am yet to be convinced that unquestioningly 'embracing invasives' is a well thought-out strategy, in the Galapagos or anywhere. Not enough research has been done to really understand what the implications of allowing non-natives free-reign might be and until that is the case in a region then it would seem best to err on the side of caution. However, I am getting an increasing feeling that there is a growing movement that suggests we err the other way - to allow non-natives free-reign until proven guilty. I tend to think this is driven by economics and the needs of growing human populations, rather than science. Without doubt, there is mounting and explosive controversy as general philosophy and practice in this area is undergoing dramatic changes at this time.

Blackberries: Overwhelming ecosystems in the Galapagos. Also a big problem in Australia.

New commission to address threats to food security from Climate Change

2011-03-29T18:00:00.000+11:00

A New commission to address threats to food security from Climate Change has been set up in the UK, to look at Global food security issues. "Chaired by the United Kingdom's Chief Scientific Adviser, Professor Sir John Beddington, the Commission will in the next ten months seek to build international consensus on a clear set of policy actions to help global agriculture adapt to climate change, achieve food security and reduce poverty and greenhouse gas emissions."

Looking on the bright side

2011-03-07T14:15:00.000+11:00

There seems to be a recent trend in articles looking on the bright side of introduced species. In my previous post I linked to the controversial New Scientist article 'Aliens to the rescue', which puts forward the case that there are "Friendly Invaders" and "Alien Species Save Ecosystems". Another article along similar lines, although without the tabloid phrasing, has now appeared in Conservation Biology:

SCHLAEPFER, M. A., SAX, D. F. and OLDEN, J. D. , The Potential Conservation Value of Non-Native Species. Conservation Biology, EARLY VIEW doi: 10.1111/j.1523-1739.2010.01646.x

Such papers seem to me to be putting forward the 'pros' of introduced species as if the idea that non-natives have benefits is a new thing - but haven't we been growing 'non-native' wheat across the world for thousands of years, introducing bees for pollination etc etc? This article frustrated me as the way it was conducted reviewed mainly only the positive effects of non-native species, not balancing their examples with negatives. They do point this out, justifying it by saying such negative cases have been presented elsewhere, but really perhaps they should have put their examples into context with some balance rather than simply leaning so far to the 'pro-non-native' camp that seems to be emerging. Perhaps these articles are simply looking for citations, to say 'there are some good things about non-natives, quote...', or maybe academics are setting themselves up a Straw Man - making themselves an easier target to shoot down, by taking the pro- non-native argument to extremes.

A mediocre month

2011-02-25T17:12:00.000+11:00

Well, the last couple of months have been a bit of a disappointment really, I've not come across anything to get excited about in the literature. Thats not to say Ive not come across anything, but what Ive found hasn't exactly knocked my socks off or has left me very disappointed. Some articles I have picked up thinking they are full of promise, only to find that the data they use is really quite shaky on closer examination, or their findings are not really too far beyond common sense. These are some that I considered...

Stigall AL (2010) Invasive Species and Biodiversity Crises: Testing the Link in the Late Devonian. PLoS ONE 5(12): e15584. doi:10.1371/journal.pone.0015584

This article reaches the intriguing conclusion that lower vicariant speciation due to species invasions was responsible for the late Devonian 'biodiversity crisis'. However, I was left wondering exactly how Dr Stigall worked out that there was an increase in invasion in the late Devonian resulting in prolific invasive species. The only explanation made is based on the work of other authors, who infer that the evidence of the reduction in endemism during that period is indicative of increased interbasinal species invasions at that time (p2). As this underpins the study to some extent I wasn't happy enough with that explanation to review it fully, although her argument was persuasive enough to prompt a review in Science Daily 'Invasive Species Stop New Life'...!

Another study that seemed initially quite promising was Essl F. et al. (2011) Socioeconomic legacy yields an invasion debt vol. 108, no. 1, 203-207

However, the conclusion to this article really seems somewhat obvious, unless I'm missing something?: 'current patterns of alien-species richness may better reflect historical rather than contemporary human activities', well, these things do take a little time! I wasn't very satisfied with the discussion, I would have liked the article to consider more how historic activities relate to contemporary activities, including impacts of defense and mitigation, instead of making the somewhat simplistic conclusion that more stringent protection measures are imperative.

Finally, I have to mention the New Scientist article 'Aliens to the Rescue' , which is a very provocative article that sent quite a ripple through the community of Invasion Ecologists. Using somewhat sensationalist language to fight the corner for the aliens, Garry Hamilton argues that aliens 'may be our last line of defence against ecological destruction'! Statements such as 'there has been a big emphasis on looking at the negative side of the ledger' seem to indicate that the considerable damage done by many invasive species is nothing compared to the good some of them might do. Perhaps some of the impact of the article is in the terminology. Hamilton refers to invasives as perhaps being the good guys - when really he should perhaps have termed them 'non-natives', 'invasives' by definition implies that the species is destructive and so arguing that we should not be concerned about them simply makes no sense. Though on the whole the article seems really not very well informed and frivilous, for example the argument on page 36 that the elimination of alien feral cats on Macquarie Island was a bad thing as it led to an explosion of the rabbit population... but, hang on, rabbits are also an alien pest! Unfortunately, I feel this is a bad example of (somewhat irresponsible) tabloid science, with little awareness of how invasive species are carefully and extensively studied and managed - 'indiscriminate eradication' just doesn't happen.

Introduced plant species and rapid evolution

2011-01-14T14:29:00.000+11:00

Sometimes I come across interesting reviews by other people on F1000 that are about Biosecurity and Invasive Species. This month Mark Vellend of the University of British Columbia, Canada has found a very interesting paper on a study of herbarium records collected over the past 100+ years that tells us that environmental adaptation to dry conditions in Australia may take precedence over competitive drivers (such as decreasing vs increasing leaf size) in rapid evolution of introduced plant species in the region. Mark Vellend's full evaluation can be read here:

Vellend M: 2011. F1000.com/7408957

The summary paragraph of the review:

An ingenious use of herbarium specimens across 23 exotic plant species in Australia has revealed that phenotypic changes following introduction are both very common, and in different directions than predicted by conventional wisdom.

Details of the paper:

Is rapid evolution common in introduced plant species?

Buswell JM, Moles AT, Hartley S

J Ecol. 2011; 99:214-224

December review for F1000

2011-01-07T14:25:00.000+11:00

This month's paper that we have reviewed for F1000 is a combined effort by a number of authors, including an old colleague at the University of Leeds - Dr Koos Biesmeijer, whom I worked with on a couple of proposals before I left the UK. It is a very interesting read and raises many important questions by taking an unusually holistic perspective of examining the combined impacts of climate change and alien species on pollination.

Multiple stressors on biotic interactions: how climate change and alien species interact to affect pollination
Schweiger, O; Biesmeijer, J. C.; Bommarco, R.; Hickler, T.; Hulme, P.; Klotz, S.; Kühn, I.; Moora, M.; Nielsen, A.; Ohlemüller, R.; Petanidou, T.; Potts, S. G.; Pyšek, P.; Stout, J. C.; Sykes, M.T.; Tscheulin, T.; Vilà, M.; Walther, G-R.; Westphal, C.; Winter, M.; Zobel, M.; Settele, J. Biological Reviews, 2010 Nov, 85(4): 777-795
DOI: 10.1111/j.1469-185X.2010.00125.x

Our Review:
Faculty of 1000: 2011. F1000.com/7338958

This paper provides a rich and novel overview of hypotheses on the combined impacts of climate change and alien species on a key ecosystem service: pollination. It provides a very good summary of the state of research, as well as a plethora of pointers to future study.

The paper takes a holistic view of potential changes to plant-pollinator systems under the impacts of climate change combined with introduced species, about which little is known. The paper examines evidence for both direct and indirect impacts, as well as complex, multi-trophic effects.

A series of tables highlights key indications in the literature that lead the authors to state general 'hypotheses' about what this will mean for plant-pollinator interactions. The first table highlights the climate-change effects, which are largely predicted to be negative, mainly due to phenological mismatch, as confirmed by another recent study showing pollinator activity is beginning to precede flowering times [1].

The second table highlights research on the direct effects of alien species within trophic levels on existing plant-pollinator systems, leading to a number of hypotheses that that indicate the extinction of plants or pollinators. However, when direct effects across trophic levels are examined (Table 3), there are potentially some positive outcomes, as alien pollinators may compensate for phenological mismatches.

The paper goes on to address more complex interactions, such as indirect effects of alien species across trophic levels and to explain differences in plant and pollinator responses in terms of "social and generalist" vs. "solitary and specialist" species.

This paper does a good job of summarizing a complex and growing research field, highlighting the importance of assessing multiple drivers and taking an ecosystem perspective, as well as distilling from the literature some guiding hypotheses for future research.

Reference: [1] Sparks et al. Ecol Entomol 2010, 35:788-791 DOI:10.1111/j.1365-2311.2010.01226.x.

November review for F1000

2010-12-14T14:11:00.000+11:00

This month we decided to review a novel application of network theory to the horticultural industry. This paper is on work that is still very much evolving, however it shows great potential for further studies of plant trade networks.

Disease spread in small-size directed trade networks: the role of hierarchical categories M. Pautasso, X. Xu, M.J. Jeger, T.D. Harwood, M. Moslonka-Lefebvre and L. Pellis Journal of Applied Ecology. 2010 Dec; 47(6):1300-1309
DOI: 10.1111/j.1365-2664.2010.01884.x

Our Review:
Lonsdale M: 2010. F1000.com/6722956

This article is a novel theoretical application of network theory to the horticultural industry, which might ultimately contribute to a better understanding of the way in which plant diseases may spread.

This article demonstrates that structural change in the trade in plants may have an influence on the chances that a disease epidemic will occur. For example, increasing the number of producers and retailers relative to the number of wholesalers will tend to increase epidemic spread in some kinds of networks. In other kinds of networks (called 'scale-free'), which are characterised by super-connected individuals, the relative number of producers and retailers to wholesalers is not a key driver of epidemic spread.

Definitions of network structures are given in the paper and in a companion paper shortly to be published (available now as 'early view') that gives a review of this area and a more in-depth explanation of the terminology [1]. The study of networks in relation to plant diseases is a relatively novel field in comparison with network studies of diseases in humans and animals [2].

The next step for this work will be to align it with 'real' horticultural trade networks, to identify which theoretical representation fits best with existing networks. Once this is established, the findings in this paper may enable hypotheses to be developed on how structural changes in the plant trade will impact on the spread of epidemics and advise management strategies.

A better understanding of horticultural trade networks may equally improve understanding of 'invasion pathways' and for invasive plants themselves, and not just their diseases, as plant invaders are often brought in by trade in the horticultural industry, and their propagation through the trade possibly has epidemic-like properties.

References: [1] Moslonka-Lefebvre et al. Phytopathology 2010, Nov 9, Epub ahead of print
DOI: 10.1094/PHYTO-07-10-0192
[2] Jeger et al. New Phytol 2007, 174:279-97 DOI: 10.1111/j.1469-8137.2007.02028.x

More evidence of earlier flowering times under climate change

2010-12-06T15:40:00.002+11:00

A UK-based paper has recently put together a 'meta-analysis' of data from the past 200 years to show that British Flowering plants have been flowering 2-12 days earlier over the last 25 years than at any time in the past two centuries, on average. Although this doesn't contrast natives and invasives (it would be interesting to know if that would be possible with this data), it complements the first paper we reviewed for F1000 on the Thoreau's wood data (Concord, Massachusetts (USA)) that demonstrated evidence of earlier flowering dates for both natives and non-natives, however with non-natives flowering 11 days earlier on average than natives over the last 100 year. I would be curious to know if a similar study could be conducted with the UK data by Amano et al. to that of Willis et al. to provide further evidence for the interesting findings in that paper (see our review here).

T. Amano, R.J. Smithers, T.H. Sparks and W.J. Sutherland (2010) A 250-year index of first flowering dates and its response to temperature changes Proc. R. Soc. B vol. 277 no. 1693, 2451-2457

A review of the Amano et al paper for F1000 by Sandra Knapp can be read here, she rated this paper 'exceptional': Faculty of 1000: 2010. F1000.com/6560956

What Makes an Alien Invasive?

2010-11-22T14:35:00.000+11:00

This is the title of the forthcoming conference of the Association of Applied Biologists in the UK, to be held in Edinburgh. The conference is to take place in early December (soon!) but it looks like it is still possible to register. More details on the conference website here.

The conference looks very interesting - it is focused in Europe however it asks questions of global relevance. The key question the conference asks, "what criteria make alien species become an invasive species?" can be asked at all stages of an 'invasion' - pre-border, at border and post-border. It is foremost when thinking about risk assessment, detection and management of alien species as potential invasives.

Plant Invasions: theoretical and practical challenges

2010-11-18T12:08:00.001+11:00

"Plant Invasions: theoretical and practical challenges" is the title of a recent collection of papers in the journal Biological Invasions.
This collection of papers span a wide range of topics relating to the study and management of plant invasions. Richardson et al provide a summary article at the start of the special issue, recognizing 6 broad themes amongst the papers:

• ‘‘big-picture’’ analyses to derive new insights on invasion dynamics for large regions and biomes;
• detailed studies on major invasive species, drawing on insights from con-specific and con-generic invasions in other regions;
• genetic studies to elucidate invasion processes and inform management strategies;
• assessment of the relative role of climate matching in shaping invasion patterns through the analysis of patterns of distribution of invasive species along elevational gradients;
• assessing potential changes in invasion dynamics and impacts under climate change;
• new approaches for integrating advances in the understanding of invasion ecology to improve management

I haven't had a chance to read these yet, however looking through the studies those that examine the role of climatic factors in invasions and also those that look at the effects of climate change stood out to me. There is also a strong 'practical' leaning in this special issue, with a number of papers tackling 'management' issues.

October Review for F1000

2010-11-17T10:39:00.000+11:00

Oops I'm a little behind on putting our last review up here - its nearly time for the next one! Last month we reviewed a global 'meta-analysis' of data from across the globe that indicates higher water use by invasive species when compared with co-occurring natives. Although some bias was evident in the data used to conduct the analysis (well, it was a US-based paper in a US-based journal...) we feel the results are still broad enough to present a persuasive case.

Comparative water use of native and invasive plants at multiple scales: a global meta-analysis. Cavaleri MA, Sack L Ecology. 2010 Sep; 91(9):2705-15
DOI: 10.1890/09-0582.1

Our Review:
Lonsdale M: 2010. F1000.com/5807964
Copyright F1000

This paper gives some clear indications of the increases in water use that may arise as a consequence of invasive species in a variety of ecosystems across the globe. The paper stands out as it not only analyses differences between co-occurring native and invasive species of the same growth form in a comprehensive fashion, but also suggests mechanisms for these differences and avenues of further research. The study also refutes the theory that invasive species are successful due to more efficient resource use when compared with natives.

This paper presents the results of a meta-analysis of data from across the world on the water use of native vs. invasive plants at three different scales: leaf, plant, and ecosystem, in a range of biomes. The results indicate that invasive species are likely to dramatically increase water use when compared with co-occurring natives of the same growth form. Even greater impacts are expected when larger species replace smaller species. Although some benefits might be gained in terms of carbon sequestration in larger plants replacing small ones, there is a trade-off in water use.

At the leaf scale, invasives were found to have dramatically higher stomatal conductance and photosynthetic capacity, indicating higher metabolic rates. The invasive species' pre-dawn leaf water potential was commonly more negative than natives too. However, at the plant scale, there was little difference in the indicators between invasives and natives. At the ecosystem scale, invasive-dominated ecosystems had higher daily sap flow rates per unit ground area than native-dominated ecosystems. These results also varied with biome.

Although we do feel the authors have produced a comprehensive study and have looked at a range of biomes, an examination of Appendix A shows that North America dominates with over 50% of data used in the analysis coming from this region and the Pacific studies were nearly all from Hawaii. There is a conspicuous absence of Australian, European, and Asian studies from the meta-analysis. Further expansion of the data into these continents would increase the generality of the results.

September Review for F1000

2010-10-13T08:13:00.000+11:00

The paper we chose to review this month was a little different in that it demonstrates a method of surveying for pest-resistant specimens involving 'citizen science'. The article is straightforward, clearly showing that there can be significant benefits to involving volunteers in biosecurity-related surveys where time is of the essence. In Australia, an example of where such an approach has been used is in surveys for fire ants in Queensland - read more about that here.

Using Citizen Science Programs to Identify Host Resistance in Pest-Invaded Forests.
Ingwell LL, Preisser EL, Conservation Biology, article first published online: 23 AUG 2010 (Early View)

DOI: 10.1111/j.1523-1739.2010.01567.x

Our Review:
Mark Lonsdale: Faculty of 1000 Biology, 12 Oct 2010
http://www.f1000biology.com/article/id/5501958/evaluation
Copyright F1000

This paper gives a clear demonstration of the advantages of involving large numbers of volunteers in a survey for trees resistant to a pest. It highlights the possibility that the human population could be an important part of a resilient biosecurity system if sensitised to biosecurity risks.

The paper uses the case study of surveys for surviving Hemlock trees that have been exposed to the insect pest hemlock woolly adelgid (Adelges tsugae) to illustrate the value of enlisting volunteers for this kind of survey. Surveys took place in Connecticut, Massachusetts, New Jersey, New York, Pennsylvania and Rhode Island. The researchers provided brochures describing the pest, effects on the host and the likely phenotypic characteristics of resistant trees. This enabled the surveying of hundreds of hemlock forests for healthy trees in a relatively short time-frame -- time is often of the essence in such surveys, e.g. to counter pre-emptive logging. The cuttings obtained by the survey showed resistance to hemlock woolly adelgid and are to be used in breeding programmes. As this paper suggests, finding ways to engage 'citizen scientists' in biosecurity and invasion management programmes can have clear advantages and should be considered as a 'standard' response strategy.

MSN feature invasive species

2010-09-23T14:24:00.002+10:00

Just noticed as I logged out of my hotmail today that MSN have put a feature up on invasive species! Worth a look...
http://news.uk.msn.com//environment/wildlife/photos.aspx?cp-documentid=154739345

August review for F1000

2010-08-30T11:32:00.000+10:00

Optimal management strategies to control local population growth or population spread may not be the same. Shea K, Jongejans E, Skarpaas O, Kelly D, Sheppard AW Ecol Appl 2010 Jun 20(4):1148-61

Our Review
Mark Lonsdale: Faculty of 1000 Biology, 16 Aug 2010
http://f1000biology.com/article/id/4671963/evaluation
Copyright F1000

This paper provides a good example of how a model for population processes can be used to inform management decisions at a regional scale for an invasive plant, Carduus nutans. Mechanistic approaches in both population dynamics and dispersal simulation are combined to good effect in this study. Modellers are increasingly using such methods in spatial ecology to achieve a better understanding of drivers that can lead to important management strategy recommendations, as demonstrated here.

The authors incorporate lifecycle processes in a matrix mode of local demography with a mechanistic dispersal model (termed a 'vital-rate' approach) and show that certain processes have divergent effects on either spread or growth of the population. Managers should therefore consider their aims (e.g. whether to control population growth or spread) when trying to identify appropriate management strategies. Management strategies may also need to vary between regions (both native and invaded) as the life cycle and 'vital-rates' of the invasive vary with region. The mechanistic approach of Shea et al. confirms that the reduction of micro-site availability is beneficial in reducing both the rate of population growth and spread, as it would limit key processes of germination and establishment. They also find with their model that differing methods of biocontrol will have differing impacts on either population growth or spread, thus informing management strategies. Biocontrol can be expensive and it will be useful to make explicit early decisions about what kind of biocontrol agents to search for.

A global perspective on current changes in horticulture

2010-07-30T15:33:00.000+10:00

My new office mate found an interesting paper today, about current dynamics in the global horticultural industry that may well have implications for invasives:
Review
Structural change in the international horticultural industry: Some implications for plant health
K. Dehnen-Schmutza, O. Holdenriederb, M. J. Jegerc and M. Pautassoc
Scientia Horticulturae Volume 125, Issue 1, 31 May 2010, Pages 1-15
doi:10.1016/j.scienta.2010.02.017

Short notice - talk on in half an hour!

2010-07-22T14:34:00.000+10:00

Public Seminar – Entomology Lecture Theatre Room, Level 2, Bldg 101 Clunies Ross Street, Black Mountain.

Thursday 22nd July 3.00 pm

Speaker: Dr Jean-Baptiste Pichancourt, CSIRO Entomology (based in Brisbane)

Title: ‘Jack-and-Master’ species: when adaptive phenotypic plasticity maximizes geographic ranges and their transformations.

Abstract: Theories suggest that phenotypic plasticity may play an important role in invasiveness and in shaping species distributions and their transformations at large scales.

Here we confirm expectations on the invasive plant Parkinsonia aculeata, using a long-term, continental-scale field study across various climatic and habitat gradients.

Furthermore, we show that the trait of phenotypic plasticity is itself under natural selection thereby providing further flexibility in range expansions or shifts.

Climate change and weed pests in South Australia

2010-07-09T11:59:00.001+10:00

This article and also this article (the latter giving a bit more detail) highlights work done here at CSIRO by Darren Kriticos (my boss!). He has modelled the effects of climate change on invasive plants in South Australia and identified significant shifts in distribution that may occur .

Invasive Species: News and Events - Conferences and Workshops: Conference Calendar

2010-07-08T17:01:00.000+10:00

Invasive Species: News and Events - Conferences and Workshops: Conference Calendar

Invasive Species Council

2010-07-08T16:03:00.000+10:00

Invasive Species Council
Some interesting stuff on here about 'tackling some of Australia's toughest environmental threats'

July review for F1000

2010-07-06T10:18:00.001+10:00

Facilitation cascade drives positive relationship between native biodiversity and invasion success. Altieri AH, van Wesenbeeck BK, Bertness MD, Silliman BR Ecology 2010 May 91(5):1269-75

Our Review
Mark Lonsdale: Faculty of 1000 Biology, 5 July 2010
http://f1000biology.com/article/id/3815957/evaluation
Copyright F1000

This article is interesting because it provides plot-scale support for the role of native species in facilitating invasions that helps explain the positive relationship between native species diversity and invasibility typically seen at the landscape scale.

The 'invasion paradox' [1] in ecology stems from a debate started back in the 1950s when Elton examined the relationship between native species diversity and invasive species establishment [2]. The paradox is that, on the one hand, many landscape-scale studies have shown a positive relationship between native diversity and invasibility, whilst, by contrast, many studies at the smaller experimental scale have shown a negative relationship, usually attributed to increased competition from more native species.

The present study focuses on the intertidal landscape of New England cobble beaches, particularly the ecosystem comprising invasive Asian shore crab (Hemigrapsus sanguineus) and the native plant community in which "cordgrass ameliorates solar stress and provides an attachment surface for ribbed mussels (Geukensia demissa) which, in turn, provide stable hard substrate and crevice space for other organisms" (p. 1270). The authors demonstrate the relationship between higher invasive crab densities and greater diversity of native species of algae and invertebrates (facilitated by the presence of cordgrass and ribbed mussels, i.e. a 'facilitation cascade'). The authors show that the abiotic stress (desiccation, thermal and instability) in the system is moderated by the presence of the cordgrass and ribbed mussels. This, in turn, increases the native species richness, which, in turn, reduces the mortality of the Asian shore crabs at larger scales. The authors claim that such 'facilitation' has "played an important but unrecognized role" in many studies that have focused on the role of competition when examining relationships between native biodiversity and invasiveness (p. 1273). This study clearly shows that there is a need to encompass multiple trophic levels, multiple spatial scales and multiple theories about the interactions driving invasibility (i.e. not just 'competition') when trying to understand drivers of invasive species establishment.

This study has shown positive effects of increasing native diversity on the success of a single invasive species. The next step will be for future studies to examine whether this can be translated to a positive effect of increasing native diversity on success for a range of invasive species, and thus on invasive species diversity (something that can only be inferred from these results). This would then connect more directly with empirical studies at the landscape scale, which have shown that higher native species diversity can lead to higher invasive diversity.

References: [1] Fridley et al. Ecology 2007, 88:3-17. [2] Elton CS, The ecology of invasions by animals and plants. London: Methuen, 1958.

Invasive Earthworms - not such friendly soil munchers?

2010-05-28T16:17:00.001+10:00

I saw this link on the Bioinvasion and Ecoservices blog: it is a BBC news article about a very interesting paper just out that shows Earthworms actually eat seeds and seedlings, not just dead matter. This has major implications for the spread of the humble Earthworm that is making is way (with the help of people, of course) from Europe across other continents. Although there always going to be benefits of worms, such as nutrient cycling, their presence in new landscapes may potentially cause plant species extinction as the worms begin to eat their seedling which previously had no 'predators'.

N. Eisenhauer, O. Butenschoen, S. Radsick and S. Scheu (in press, May 2010) Earthworms as seedling predators: Importance of seeds and seedlings for earthworm nutrition Soil Biology and Biochemistry

(image found on the Mad Science website)

Dispersal of Invasives - Ecological Applications

2010-05-28T15:56:00.000+10:00

I noticed these papers a little while ago in the April 2010 issue of Ecological Applications, but seeing them again in an email alert made me think I should have put them on my blog and perhaps highlight them for a F1000 review:

The effects of temporally variable dispersal and landscape structure on invasive species spread (2010) M.E. Andrew and S.L. Ustin Ecological Applications Vol. 20, No. 3: 593-608.

Contributions of demography and dispersal parameters to the spatial spread of a stage-structured insect invasion (2010) T.E.X. Miller and B. Tenhumberg Ecological Applications Vol. 20, No. 3: 620-633.

As they are modelling papers they are particularly interesting to me. The first provides some very interesting general insights on initial rates of spread gained from remote sensing studies and simulation modelling of the dispersal of invasive species. The second is a good demonstration of the way in which modelling can be used to identify which points in the life cycle should be targets of management.

May Review for F1000

2010-05-12T09:50:00.001+10:00

Use of Abundance of One Species as a Surrogate for Abundance of Others.
Cushman SA, McKelvey KS, Noon BR, McGarigal K (2010) Conservation Biology Published Online: 7 Jan 2010 (early view) DOI: 10.1111/j.1523-1739.2009.01396.x

We have gone a little bit away from the biosecurity and invasive species theme this month, as we felt this paper was a very important more general paper. There is a long history of the use of surrogate 'indicator' species in conservation management and scientific research that has never seemed entirely justified. Others have challenged these ideas before, however, this paper provides a very clear message that caution should be used - proving rather than assuming that the abundance of one species may represent the abundance of another.

Our Review
Mark Lonsdale: Faculty of 1000 Biology, 11 May 2010
http://f1000biology.com/article/id/3184963/evaluation
Copyright F1000

This stimulating article challenges the long-standing use of 'indicator' species concepts in conservation ecology. Such surrogate approaches, where a single species is assumed to represent others, have been used in many scientific studies and to justify management strategies.

This is a refreshing paper because it challenges the 'indicator' species concept in conservation biology, showing that for such a concept to be valid in the study and management of an ecosystem it 'must be demonstrated rather than assumed'. The authors carried out an extensive survey of birds in the Oregon Coast Range. They used two methods to group the birds into potential 'surrogate' groups: firstly, an 'a priori' grouping into life-history categories and, secondly, grouping 'empirically' using cluster analysis. The results for both methods show that some correlations can be found within groups that were defined both a priori and empirically. However, even when such correlations are found they do not explain a very high percentage of variance (generally below 20%), with the empirical grouping providing stronger patterns, largely because this grouping was based on the same dataset as the surrogacy test. Therefore, the empirical groupings represent the maximum variance explained by grouping and are probably unique to the dataset and location.

Overall, the results give little support for the use of indicator species to infer the abundance of other bird species populations at two spatial scales (i.e. controlling for spatial dependence), as 'the lack of strong surrogacy is compelling' (pp 10). The authors were also able to highlight from their results that certain types of surrogacy are unlikely to exist, refuting concepts of 'guild-indicator' (use of a species as an indicator for an ecological guild, see Block et al., 1987 [1]) and 'management-indicator' species (use of a species as an indicator because its welfare is presumed to be an indicator of the welfare of other species in a habitat, see Landres, 1992 [2] -- an example is the use of the concept by the USDA for the management of the Sierra Nevada).

The authors explain the failure of the indicator species concept with reference to ecological niche theory, stating that coexisting species are likely to differ in at least one critical niche dimension that will preclude them from acting as surrogates for one another.

This article is not the first to highlight the importance of making assumptions about surrogate relationships in ecosystems. For example, Hurlbert (1997) questioned the popular use of the concept of 'keystone' species, showing that it couldn't be assumed that there exist species within a system that are somehow more 'important' or influential than others and that such species are unlikely to be easily identified[3]. Others have also cautioned the use of surrogate species, such as Wiens et al. (1998) [4], though not as strongly as this paper.

The paper's conclusions are clear in stating that justifications for conservation and research emphasis on particular species should focus on the importance of the species itself, as it is unlikely that there will be sound justification for any one species' abundance to represent that of others.

References:
[1] Block, W. M., Brennan, L. A. and Gutierrez, R. J. (1987) Evaluation of guild-indicator species for use in resource management Environmental Management 11: 265-269 doi: 10.1007/BF01867205

[2]Landres, P.B. (1992) Ecological indicators: panacea or liability? Pages 1295-1318 in McKenzie, D.H., Hyatt, D.E. and Mcdonald, V.J. (eds) Ecological Indicators, Volume 2 Elsevier Applied Science, New York

[3]Hurlbert (1997) Functional importance vs keystoneness: Reformulating some questions in theoretical biocenology Austral Ecology 22 (4), Pages 369 – 382 doi: 10.1111/j.1442-9993.1997.tb00687.x

[4] Wiens, J.A., G.D., Holthausen, R. S., Wisdom, M.J. (2008) Using Surrogate Species and Groups for Conservation Planning and Management BioScience 58(3):241-252 doi: 10.1641/B580310

Two interesting F1000 reviews (invasives)

2010-05-07T10:43:00.000+10:00

I've just received the bulletin of the latest reviews from F1000 and noticed a couple of interesting reviews for papers on invasive species...

van Kleinen, M, Weber, E and Fischer, M (2010) A meta-analysis of trait differences between invasive and non-invasive plant species Ecology Letters Volume 13 Issue 2, Pages 235 - 245

This paper is flagged as a 'must read' - the reviewer (Bernhard Schmid of the University of Zurich, Switzerland) must have been very impressed with the paper. His reason for highlighting it is that:

"This is the most comprehensive quantitative synthesis comparing invasive with native plant species. It demonstrates clearly that invasive species generally have higher values for growth-related traits." copyright F1000.

The review can be seen here on F1000 website.

Dick, J.T.A., Armstrong, M, Clarke, H.C., Farnsworth, K.D., Hatcher, M.J., Ennis, M., Kelly, A. and Dunn, A.M. (2010) Parasitism may enhance rather than reduce the predatory impact of an invader Published online before print April 14, 2010, doi: 10.1098/rsbl.2010.0171

This paper is highlighted as the reviewers Michael W McCoy and Ben Bolker of the University of Florida, USA feel:

"This article gives a simple, clear example of parasites enhancing predator impact on prey -- a nice addition to the catalog of observed trait-mediated indirect interactions (TMIIs) in communities -- and (briefly) considers the effect of this change on the community-level impact of an invading species." copyright F1000.

The review can be seen here on F1000 website.

Latest Journal of Applied Ecology - some interesting papers

2010-04-29T11:47:00.000+10:00

There is a good section in the Journal of Applied Ecology this month on invasives/biocontrol, with 3 papers that caught my eye. Not sure yet if we will review them for F1000, I will put forward the first one to Mark Lonsdale, but here is a summary of each:

Predicting parasitoid accumulation on biological control agents of weeds Q. Paynter, S.V. Fowler, A.H. Gourlay, R. Groenteman, P.G. Peterson, L. Smith and C.J. Winks (2010) Journal of Applied Ecology Volume 47 Issue 3, 575-582
This paper from New Zealand gives some potentially generalizable insights into the relationship between parasitoid, biocontrol agent and weeds and the impacts on non-target organisms. I like the hypotheses put forward and believe it could lead to further research, so we may well review this one. From the abstract:

"Although our conclusions are based on an unavoidably limited data set, we conclude that biocontrol agents that escape attack from parasitoids are more likely to suppress weed populations and should be less likely to have significant indirect non-target effects in food webs. Biocontrol practitioners can reduce the chance of weed biocontrol agents attracting species-rich parasitoid faunas after introduction by (i) selecting agents that have species-poor parasitoid faunas in their area of origin, and/or (ii) avoiding agents that have 'ecological analogues' awaiting them in the introduced range."

Management response to one insect pest may increase vulnerability to another M.D. Klingenberg, B.S. Lindgren, M.P. Gillingham and B.H. Aukema (2010) Journal of Applied Ecology Volume 47 Issue 3, 566-574
This Canadian study is an interesting case-study of the multiple factors that contribute to the exacerbation of an insect pest outbreak. From the abstract:

"This study demonstrates how a management response to a large insect outbreak, itself mediated by anthropogenic factors, can predispose reforested stands to additional, unanticipated threats from other insects. Reforestation strategies following outbreaks of mountain pine beetle may need to include harvesting larger salvage blocks to minimize edge effects and reduce mortality from Warren root collar weevils. Moreover, the inclusion of deciduous non-host tree stock in planting mixes might reduce insect movement and limit tree mortality because of Warren root collar weevils."

Spatial and temporal variability in host use by Helicoverpa zea as measured by analyses of stable carbon isotope ratios and gossypol residues G. Head, R.E. Jackson, J. Adamczyk, J.R. Bradley, J. Van Duyn, J. Gore, D.D. Hardee, B. Rogers Leonard, R. Luttrell, J. Ruberson, J.W. Mullins, R.G. Orth, S. Sivasupramaniam and R. Voth (2010) Journal of Applied Ecology Volume 47 Issue 3, 583-592
I like this paper as it uses an interesting technique to analyse the true effectiveness of a 'high dose/refuge' management strategy for Bacillus thuringiensis (Bt) resistance in target pests such as the cotton bollworm (CBW), Helicoverpa zea (Boddie) in transgenic Bt cotton Gossypium hirsutum L in the USA. Data on stable carbon isotope ratios was used to assess the importance of refuges, a key part of the current management strategy. It was found that these structured cotton refuges only play a relatively minor role in the management for this species.

April Review for F1000

2010-04-13T14:31:00.002+10:00

An Experimental Test of Darwin’s Naturalization Hypothesis in Jiang, Jiaqi Tan, and Zhichao The American Naturalist, vol. 175, no. 4 (April 2010) pp. 415–423 DOI: 10.1086/650720

We decided to review the above paper as our April review for F1000. This article is interesting because it is an elegant experimental test of Darwin's ‘Naturalization hypothesis’: a theory about the role of interspecific competition in invasion success.

Our Review
Mark Lonsdale: Faculty of 1000 Biology, 19 Apr 2010 http://f1000biology.com/article/id/2902956/evaluation
Copyright F1000

This article is interesting because it is an elegant experimental test of Darwin's 'naturalization hypothesis' -- a theory about the role of interspecific competition in invasion success. Darwin theorised that introduced species would be more successful in colonising communities from which their close relatives are absent. These authors set up experimental communities of bacteria and then introduced an 'invading' bacterium. They found that invaders that were more closely related to the experimental community were less likely to establish. They also found that this effect was more pronounced when the invaded community also included a 'predator' (this was a protist bacterivore).

Darwin's justification for his theory was that competition would be more intense between more closely related species and these results are certainly consistent with that idea. However, a further reason would be that natural enemies (predators and pathogens) pre-adapted to the invader would be more likely to be present in the community of closely related species. Although the authors test the hypothesis with the introduction of a predator, this experimental set-up does not really get at this alternative explanation, focusing more on competition as the driving mechanism. A similar study {1} concluded that, in an experimental plant community, an exotic plant closely related to natives in the invaded community may experience more damage from herbivores than a phylogenetic outlier. Darwin's naturalization hypothesis is a hot topic in the literature at the moment, and a review paper just published outlines the key debates and studies {2}. This review also provides some important guidelines for future studies in this field. Now that the authors have developed a functioning experimental system, it will be interesting to see them explore the relationship between invasibility and functional diversity, which has been a major focus of research over the last 10 years. As the authors point out, the range of diversity used in their microcosms is rather small in this experiment; they will need to create a larger gradient of species diversity. Phylogenetic similarity is unlikely to be present where an invasive species arrives into a community from some distance (e.g. another continent). Ecological niches and functional similarity are likely to play a more important role in this case. Overall, the current paper is an exciting piece of work that provides a valuable experimental system for future studies to delve yet deeper into this intriguing topic.
References:
[1] Hill, S.B. and Kotanen, P.M. (2009) Evidence that phylogenetically novel non-indigenous plants experience less herbivory Oecologia 161:3 pp 581-590

[2] Thuiller, W., Gallien, L., Boulangeat, I., de Bello, F., Münkemüller, T., Roquet, C. and Lavergne, S. (2010) Resolving Darwin's naturalization conundrum: a quest for evidence Diversity and Distributions Early View online DOI: 10.1111/j.1472-4642.2010.00645.x

Public seminar at CSIRO

2010-04-13T10:19:00.000+10:00

Picking winners in biological control: holy grail or poisoned chalice

WEDNESDAY 14 APRIL AT 3PM
Public seminar
Dr Raghu Sathyamurthy – Arid Zone Research Institute, Dep. Resources Northern Territory
Venue: CSIRO Entomology
Abstract:
Managing the risks and costs of classical biological control while harnessing its benefits is an ongoing challenge for its utility in invasive species management. Significant economic and ecological gains can potentially be made in this regard, if we can predict the agents that have the highest likelihood of managing their target weed/insect pest (i.e. pick "winners"), and prioritise their importation, risk assessment and release. Developing innovative approaches to picking winners has therefore been the 'holy grail' of the discipline, a pursuit hastened in recent decades by the detection of non-target effects of ineffective biocontrol agents. In this talk I will outline one potentially valuable approach to such a pursuit. Using a case study of my research in weed biological control, I illustrate how a conceptual framework to tackle the mechanistic basis for invasiveness can help in selecting and prioritising agents with a higher likelihood of success. I conclude with some caveats on using such approaches, to avoid accidentally sipping from poisoned chalices in the pursuit of this holy grail

The threat when invasives hybridize...

2010-03-18T17:46:00.000+11:00

Rapid spread of invasive genes into a threatened native species Benjamin M. Fitzpatrick, Jarrett R. Johnson, D. Kevin Kump, Jeramiah J. Smith, S. Randal Voss and H. Bradley Shaffer PNAS Feb 2010 doi: 10.1073/pnas.0911802107
(From the abstract): Models (in combination with field study) suggest that the rate of displacement of native by invasive alleles can be rapid and inevitable if they are favored by natural selection. The results illustrate that genetic and ecological factors need to be carefully weighed when considering different criteria for protection, because different rules could result in dramatically different geographic areas and numbers of individuals being protected.

Non-native bug to control Japanese Knotweed in the UK

2010-03-17T09:29:00.000+11:00

In the news reports that the UK will shortly go ahead and introduce a host-specific non-native psyllid called Aphalara itadori to try to control the spread of the highly invasive Japanese Knotweed.

Australian evidence of climate change

2010-03-16T15:46:00.000+11:00

From a news report on redOrbit:
CSIRO, in a joint "State of the Climate" report with the Bureau of Meteorology, presented findings in a report that the country's mean temperature has increased by 0.7 degrees Celsius in the past 50 years, though some areas have experienced as much as a 1.5 to 2 degree hike in temperatures...

According to the report, as it was quoted in a March 15, 2010 Reuters UK story, "There is greater than 90 percent certainty that increases in greenhouse gas emissions have caused most of the global warming since the mid-20th century...Based on data collected over the past 100 years, the CSIRO scientists claim that they expect the average temperatures in Australia to spike by another 0.6 to 1.5 degrees Celsius in the next two decades.
Another article claims this will be the result for cities like Brisbane and Sydney by 2050:

I still can't believe some people are climate change sceptics, but, unbelievably, I was cornered by one after my talk in Brisbane at Global Biosecurity! He was not a scientist I must add. To believe 'climate change' is a figment of politicians' imagination is simply crazy-talk. Whether political handling of climate change is right is another issue, but the evidence for climate change like this is really impossible to dismiss.

Australian ants may help control cane toads!

2010-03-16T14:55:00.000+11:00

Using a native predator (the meat ant, Iridomyrmex reburrus) to reduce the abundance of an invasive species (the cane toad, Bufo marinus) in tropical Australia Georgia Ward-Fear, Gregory P. Brown and Richard Shine Journal of Applied Ecology April 2010, 47, 273–280 doi: 10.1111/j.1365-2664.2010.01773.x

A new study from the University of Sydney that indicates native predatory ants in Queensland can be encouraged to predate on immature cane-toads spatially restricted to the edge of waterbodies. As the ants are native there is limited 'colateral' damage to the local environment, giving encouraging results that they may act as an effective and ecologically sensitive biocontrol for this costly invasive.
This was in in the news back in February.

F1000 review - candidates for April

2010-03-12T10:28:00.002+11:00

Already Ive come across some likely candidates for our next f1000 review, so I thought Id post the articles I find this month prior to meeting up with Mark Lonsdale to choose our favourite for review...
Managing plant symbiosis: fungal endophyte genotype alters plant community composition Jennifer A. Rudgers, Susan Fischer, Keith Clay Journal of Applied Ecology,Volume 47 Issue 2 (April 2010) pp 468-477
DOI: 10.1111/j.1365-2664.2010.01788.x
I came across this in Nature News: Applied ecology: Grass and the X factor (Nature 464, 172 (11 March 2010) | doi:10.1038/464172b) This is an interesting article as it takes the examination of genotypes and their impacts on plant community composition one step further, by testing whether genotypes of plant symbionts influence plant community composition. The plant they examine is Tall Fescue, an invasive grass species. Their findings therefore have applications for conserving wild and unmanaged grassland habitats and for managing agronomic systems to reduce the spread of invasive plants.

An Experimental Test of Darwin’s Naturalization Hypothesis Lin Jiang, Jiaqi Tan, and Zhichao Pu

The American Naturalist, vol. 175, no. 4 (April 2010) pp. 415–423 DOI: 10.1086/650720

The authors conduct an experiment to test Darwin's hypothesis which posits that naturalization of nonnative species is more likely in communities in which their close relatives are absent (Darwin,1859). Although field observations have tested this hypothesis before, they have been on exotics in relatively complex communities at a large spatial scale, and were influenced by confounding factors such as habitat suitability. Thus the paper claims to be the first experimental test of the hypothesis, by subjecting simple microbial communities containing one or multiple species of naturally co-occurring bacteria with and without a bacterivorous protist species to the invasion of an alien bacterial species. The experiments turn out in favour of the hypothesis, though the generality of their findings is not clear.

Use of Abundance of One Species as a Surrogate for Abundance of Others Samuel Cushman, Kevin McKelvey, Barry Noon and Kevin McGarigal Conservation Biology Early View Published Online: 7 Jan 2010 DOI: 10.1111/j.1523-1739.2009.01396.x

Although a little off-topic, I like this paper as it adds weight to the evidence that the use of 'indicator', 'keystone' and 'umbrella' species in conservation biology is controversial at best. The conclusions offer guidance to the monitoring and conservation of ecosystems, as the results suggest that certain types of surrogacy are unlikely to reliably exist. For example, groups formed on the basis of migratory status, microhabitat association, and functional group did not receive any support.

Productivity, herbivory, and species traits rather than diversity influence invasibility of experimental phytoplankton communities Erik Sperfeld, Andrea Schmidtke, Ursula Gaedke and Guntram Weithoff Oecologia DOI 10.1007/s00442-010-1594-4 Early View Published Online: 7 Mar 2010

This paper examines experimentally how invasibility of a community is affected by the interplay of (1) productivity of the habitat, (2) diversity, (3) herbivory, and (4) the characteristics of both invasive and resident species. They experimented with aquatic microcosms to test the relative influence of these factors. Their conclusions are: Invasibility was not affected by species richness; instead, it was driven by the functional
traits of the resident and/or invasive species mediated by herbivore density. Overall, herbivory was the driving factor for invasibility of phytoplankton communities, which implies that other factors affecting the intensity of herbivory (e.g., productivity or edibility of primary producers) indirectly influence invasions.

Experimental species removal alters ecological dynamics in a natural ecosystem Wootton, JT ECOLOGY, 91 (1): 42-48; JAN 2010
A long standing theory on species invasions is that they can affect the temporal dynamics of ecological communities by altering feedback patterns and species interactions. However, novel experimental evidence from an inter-tidal community given in this paper shows that the main impact of the removal of the dominant species in the system is amplified environmental stochasticity, rather than changed feedback pathways as is emphasized in most theoretical predictions and laboratory studies.

Ultraviolet radiation affects invasibility of lake ecosystems by warm-water fish
Andrew J. Tucker et al. Ecology March 2010, Vol. 91, No. 3: 882-890.
The authors examine how underwater UVR is regulating the success of a warm-water fish invasion of exotic bluegill sunfish (Lepomis macrochirus) in Lake Tahoe, California and Nevada, USA. They find that the water quality has an impact on the ability of the bluegill sunfish to survive, though other factors such as a species' own ability to adapt are important in general terms. Other studies have shown that UVR can have an important influence on species distribution and community composition. This article now shows that UVR along with other abiotic factors in aquatic systems is potentially also an important control on the invasibility of the system.

Aphid genome reveals its 'Achilles heel'

2010-03-11T16:23:00.000+11:00

An interesting article Aphid genome reveals its 'Achilles heel' on a CSIRO-led CRCNPB project on the genome of the pea aphid. Their results appeared recently in PLoS Biology (The International Aphid Genomics Consortium 2010: Genome Sequence of the Pea Aphid Acyrthosiphon pisum. PLoS Biol 8(2): e1000313. doi:10.1371/journal.pbio.1000313).
If science can stop aphids flying that would certainly limit their ability to spread virus such as BYDV - though it would also make my aphid spatial migration modelling efforts somewhat redundant!

First Review for F1000

2010-03-09T09:39:00.003+11:00

Well, the review of the Willis paper on non-native vs. native species' response to climate change in Thoreau's wood is written, however, there is a small problem, someone else in F1000 already wrote a review and it was published today! Anyhow, here is both our review and that of Dr Michael Angilletta, Department of Biology, Indiana State University...

Our Review
Mark Lonsdale: Faculty of 1000 Biology, 11 Mar 2010 http://f1000biology.com/article/id/2231956
Copyright F1000

This is the first study I am aware of to demonstrate that non-native plants adapt better to climate change than native species. It has significant implications for management of the threat of invasive species under climate change.

The phenological response of flowering plants to climate plays an important role in their ability to adapt and survive. The adaptability of their phenologies will therefore determine their survival under climate change. This study uses a unique historical dataset from Concord, Massachusetts (USA) to provide a novel analysis of the different effects of rising temperatures (a mean increase of 2.4°C) in the last 150 years on native vs. non-native phenology. The results indicate that (1) non-natives are significantly better able to track seasonal temperatures than native species (using a correlation coefficient between first flowering day and annual spring temperature) and (2) ‘Invasive’ non-natives have significantly shifted their flowering time over the last 100 years to be 11 days earlier on average than natives. (Note the distinction in the paper between invasive non-natives -- those capable of spreading and dominating plant communities -- and non-invasive non-natives -- those that are not judged capable spreading or becoming dominant.)

By demonstrating this ability of non-natives to better respond to climate change the results show an advantage non-natives may have over native species. It will be interesting to explore the underlying causes of their greater adaptability, perhaps due to factors such as natural enemy release.

Review by Michael Angilletta:
Copyright F1000

This article presents alarming evidence that the flowering dates of invasive plants have better tracked long-term changes in temperature than have the flowering dates of native plants.

Willis and colleagues analyze long-term records of species abundance and flowering dates for native and non-native species of plants in Thoreau's Woods (Massachusetts, USA). Flowering dates of non-native species have tracked annual changes in temperature better than the flowering dates of native species. During the past 100 years, invasive non-natives have advanced their dates of first flowering to be 11 days earlier than natives. Not surprisingly, non-native species have also increased in abundance relative to native species. The authors could not detect any differences in morphological traits that might have explained the difference between the phenological responses of natives and non-natives. Assuming that shifts in phenology represent adaptive responses to climate change, the pattern revealed by this study has alarming implications for the future spread of non-native plants.

Global Biosecurity 2010

2010-03-06T12:54:00.000+11:00

I attended Global Biosecurity 2010 last week in Brisbane, Australia...
The conference began with two good overview plenary talks on Biosecurity issues in Australia and the US, preceded by an opening speech by CSIRO's own CEO Megan Clark.
I noted the US has some good online systems for pests and diseases, which I believe Australia will be shortly linking information to. These include EPICA, which underpins the Global Pests and Disease Database along with Cooperative Agricultural Pest Survey (CAPS).

It was good see Dr Roman Carrasco give a talk, since we were students together not so long ago at CSL. He has developed an interesting model of multi-species long distance dispersal, shortly to be published:
Comprehensive bioeconomic modelling of multiple harmful non-indigenous species L.R. Carrasco, J.D. Mumford, A. MacLeod, J.D. Knight, R.H.A. Baker Research Article, in press 2010 (available online) | doi:10.1016/j.ecolecon.2010.02.001

There has been some large-scale agent-based modelling work on the CSIRO Global Integrated Assessment Model (a multi-model project), using the CSIRO epidemiological modeling and simulation system, called EpiCast, presented by Dr David Newth and Dr Don Gunasekera, Senior Economist. This is a model of Dengue transmission in communities, which is particularly affected by water management (rain water tank hygeine) and climate change.

Of particular interest to my post-doc was the work of PhD student Craig Feutrill who has altered his research project to now focus on the same species of aphid as me: R. padi. He has some very useful data collected from a number of suction traps he built around Australia.

A couple of useful platforms for sharing ideas, discussions, models, maps and data I came across at the conference are:

NAPPFAST
A US-based system presented by Dr Roger Magarey of USDA/North Carolina State University
The Australian Biosecurity Intelligence Network (ABIN) - I am hoping this may be a better host site for the CRC Dispersal Modelling network I established a few months ago that hasn't really taken off as well as initially hoped.

The University of Western Australia seems to be building an even stronger group of dispersal modellers who were great to interact with and listen to some of them give talks. These include Dr Michael Renton, Dr James Bennett, Dr Rohan Sadler and David Savage.

There was plenty of modellers and modelling present at the conference, and I enjoyed a talk on the general importance and role of models in biosecurity by Dr David Jordan of NSW DPI. He highlighted the importance of models to the management of very large issues and their role in bringing together multiple disciplines, calling modelling 'a tool for organised collaboration'. Three cheers for modellers!

Favourable Climate Change response Explains Non-Native Species' Success in Thoreau's Woods

2010-03-06T11:00:00.001+11:00

The first paper I will review for F1000 is:
Favorable Climate Change Response Explains Non-Native Species' Success in Thoreau's Woods Charles G. Willis, Brad R. Ruhfel, Richard B. Primack, Abraham J. Miller-Rushing, Jonathan B. Losos, Charles C. Davis Research Article, published 26 Jan 2010 | doi:10.1371/journal.pone.0008878

Biosecurity and Invasive Species

F1000 January review: Science can be practical!

Mutant killer fungus

Biosecurity research efforts will be well funded in Australia

A meta-analysis of the impacts of alien plants

What is this blog about?

A global experiment in biogeography

Post-docs ahoy!

A round-up of the last month or so

Get informed on the climate debate

Saturday 20 August 9am – 5.30pmCSIRO Discovery Centre, Canberra

Species relocation under climate change - a hot topic!

Assisted colonization

Climate change - so what?

Four degrees and beyond: the potential for a global temperature increase of four degrees and its implications

Science at the Shine Dome

May review for F1000

A popular review

Mapping threatened ecosystems in Australia

Mother Nature's Melting Pot?!

April review for F1000

March Review for F1000

Embracing Invasives

New commission to address threats to food security from Climate Change

Looking on the bright side

A mediocre month

Introduced plant species and rapid evolution

December review for F1000

November review for F1000

More evidence of earlier flowering times under climate change

What Makes an Alien Invasive?

Plant Invasions: theoretical and practical challenges

October Review for F1000

September Review for F1000

MSN feature invasive species

August review for F1000

A global perspective on current changes in horticulture

Short notice - talk on in half an hour!

Climate change and weed pests in South Australia

Invasive Species: News and Events - Conferences and Workshops: Conference Calendar

Invasive Species Council

July review for F1000

Invasive Earthworms - not such friendly soil munchers?

Dispersal of Invasives - Ecological Applications

May Review for F1000

Two interesting F1000 reviews (invasives)

Latest Journal of Applied Ecology - some interesting papers

April Review for F1000

Public seminar at CSIRO

The threat when invasives hybridize...

Non-native bug to control Japanese Knotweed in the UK

Australian evidence of climate change

Australian ants may help control cane toads!

F1000 review - candidates for April

Aphid genome reveals its 'Achilles heel'

First Review for F1000

Global Biosecurity 2010

Favourable Climate Change response Explains Non-Native Species' Success in Thoreau's Woods

Saturday 20 August 9am – 5.30pm
CSIRO Discovery Centre, Canberra