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recent paper from Omri Allouche and colleagues published in the Proceedings ofthe National Academy of Science. The paper presents a simple conceptual model, in the same vein as Connell’s classic intermediate disturbance hypothesis, which accounts for large-scale diversity patterns based on aspects of species niche requirements as well as classic stochastic theory. Merging these two aspects is a critical step forward, as in ecology, there has been a tension in explaining diversity patterns between niche-based processes requiring that species exhibit differences in their needs, and stochastic (or neutral) explanations that ignore these differences, but seem to do well at large scales... Read more »
Allouche, O., Kalyuzhny, M., Moreno-Rueda, G., Pizarro, M., & Kadmon, R. (2012) Area-heterogeneity tradeoff and the diversity of ecological communities. Proceedings of the National Academy of Sciences, 109(43), 17495-17500. DOI: 10.1073/pnas.1208652109
Over the past several years a multitude of papers linking patterns of evolutionary relatedness to community structure and species coexistence. Much of this work has looked at co-occurrence patterns and looked for non-random patterns of relatedness. The key explanations of patterns has been that communities comprised of more distantly-related species is thought to be structured by competitive interactions, excluding close relatives. Alternatively, communities comprised of species that are closely related, are thought to share some key feature that allows them to persist in a particular set of environmental conditions or stress. This whole area of research is completely predicated on close relatives having more similar niche requirements then two distant relatives. This predication is seldom tested.In a recent paper in the Proceedings of the National Academy of Science, Jean Burns and Sharon Strauss examine the ecological similarity among 32 plant species and tested if evolutionary relationships offered insight into these similarities. The ecological aspects they examined were germination and early survival rates as well as interaction strengths among species. To assess how these were influenced by evolutionary relatedness, they planted each species in the presence of one of four other species varying in time since divergence from a common ancestor, creating a gradient of relatedness for each species. They found that germination and early survival decreased with increasing evolutionary distance. This surprising result means that species germinating near close relatives do better early on then if they are near distant relatives. The explanation could be that they share many of their biotic and abiotic requirements, and these conserved traits influence early success.Conversely, when they examined interaction strengths over a longer period (measured as relative individual biomass with and without a competitor), they found that negative interactions were stronger among close relatives.These two results reveal how evolutionary history can offer insight into ecological interactions, and that the mutually exclusive models of competitive exclusion versus environmental filtering do not capture the full and subtle influence of conserved ecologies. Evolutionarily conserved traits can explain both correlated environmental responses and competitive interactions.Burns, J., & Strauss, S. (2011). More closely related species are more ecologically similar in an experimental test Proceedings of the National Academy of Sciences, 108 (13), 5302-5307 DOI: 10.1073/pnas.1013003108... Read more »
Burns, J., & Strauss, S. (2011) More closely related species are more ecologically similar in an experimental test. Proceedings of the National Academy of Sciences, 108(13), 5302-5307. DOI: 10.1073/pnas.1013003108
Twenty years of research has repeatedly shown that communities with greater diversity result higher functioning -namely greater production of biomass. One of the major mechanisms producing this relationship is that different species use differing resources, such that their complementary use of resources uses the total resource pool more thoroughly, thus converting more resources into biomass. Resource preference is the product of evolution and how organisms have adapted to using various resources can influence the strength of the diversity-function.In a recent paper in Nature, Dominique Gravel and colleagues test how the evolution of specialization versus general resource use affect the strength of the diversity-function relationship. They use bacteria strains that have undergone evolution on diverse resources (generalist) versus on a singular resource (specialist). The resources in their case are different carbon substrates.Assemblages of generalists were able to use many available resources and generally had greater productivity than specialist assemblages. Generalists also show an increasing relationship between diversity and productivity, because no generalist used all resources and they still showed some preferences. Combining multiple such generalists meant that more of the total resource pool was consumed. Specialists also resulted in the positive relationship, but a much steeper one. Because specialist use many fewer carbon substrates, additional specialists meant that new resources were tapped into. Thus increasing specialist diversity resulted in more new resources being consumed than with the generalist species.While these results are logical, they are important for two reasons. First is that the strength of the relationship between diversity and function is mechanistically determined by the resource use efficiency of individual strains, and how many of the total substrates they can use. The mechanisms producing different relationships in previous experiments were hypothesized after the results analyzed, as opposed to being predicted. Second, recent work has shown that evolutionary history seems to be a better explanation of community function than the number of species. These results show how the history of evolution can have important consequences for function.Gravel, D., Bell, T., Barbera, C., Bouvier, T., Pommier, T., Venail, P., & Mouquet, N. (2010). Experimental niche evolution alters the strength of the diversity–productivity relationship Nature, 469 (7328), 89-92 DOI: 10.1038/nature09592... Read more »
Gravel, D., Bell, T., Barbera, C., Bouvier, T., Pommier, T., Venail, P., & Mouquet, N. (2010) Experimental niche evolution alters the strength of the diversity–productivity relationship. Nature, 469(7328), 89-92. DOI: 10.1038/nature09592
In discussions of the larger societal implications of scientific findings, the question of who is a scientist is frequently asked. I've talked with with creationists who invoke the authority of someone who has a PhD in a scientific discipline and happens to share their belief of supernatural origins, as a scientific authority. Does the fact that I have a PhD in ecology and evolutionary biology make me scientist or is being scientist something more?This is an important question. It goes to the core of whose authority we believe for public discussion of such issues as climate change, evolution, risks of vaccines, and so on. Regardless of how we define 'scientist', a scientist participates in science by publishing peer-reviewed research articles in scientific publications. This notion of who is a scientist has been enjoyably stretched by the publication of a paper in Biology Letters by a group of elementary school children from Blackawton, UK. In consultation with a academic scientist and under the supervision of teachers, 25 8-10 year olds devised and carried out an experiment on bee visual perception and behavior, and wrote up their results into a publishable manuscript.The students trained bees by offering them nectar rewards in different color containers. They then allowed these trained bees to forage in multicolored arenas and they conclusively show that the bees unambiguously select the colored containers they were trained on. Bess learn and adapt their behavior based on previous experience.Publishing a paper by a group of children may sound like a gimmick, but the study is very interesting. The commentary from the journal says it best: "The children's findings show that bees are able to alter their foraging behaviour based on previously learned colours and pattern cues in a complex scene consisting of a (local) pattern within a larger (global) pattern . As there has been little testing of bees learning colour patterns at small and large scales, the results can add considerably to our understanding of insect behaviour."The paper is extremely enjoyable to read and will have you chuckling to yourself. Sincerity pours from the words and I was left wondering if I could have reasoned so well at that age. The children develop hypotheses using information available to them, such as watching Dave Letterman's 'Stupid Dog Tricks'. Reading this article made me realize why I love being scientist. The students note that "This experiment is important, because, as far as we know, no one in history (including adults) has done this experiment before" and because they were given the opportunity to carryout this study they "also discovered that science is cool and fun because you get to do stuff that no one has ever done before". Too true. I could not have said it better myself.Being scientist can mean a lot of things, it can mean knowledge (which the Latin origin, Scientia means), it can mean training and acquired skills, but at its core, being a scientist means conducting research, testing hypotheses and writing publications that are deemed acceptable by other scientists. Therefore the children of Blackawton are scientists, I am a scientist.Blackawton, P., Airzee, S., Allen, A., Baker, S., Berrow, A., Blair, C., Churchill, M., Coles, J., Cumming, R., Fraquelli, L., Hackford, C., Hinton Mellor, A., Hutchcroft, M., Ireland, B., Jewsbury, D., Littlejohns, A., Littlejohns, G., Lotto, M., McKeown, J., O'Toole, A., Richards, H., Robbins-Davey, L., Roblyn, S., Rodwell-Lynn, H., Schenck, D., Springer, J., Wishy, A., Rodwell-Lynn, T., Strudwick, D., & Lotto, R. (2010). Blackawton bees Biology Letters DOI: 10.1098/rsbl.2010.1056... Read more »
Large-scale alteration of nature landscapes has had profound implications for biological diversity. The single biggest contributor to the current extinction crisis is the wholesale destruction of habitats. As habitats are destroyed, formerly contiguous landscapes become fragmented into smaller patches. But what exactly the effects of fragmentation are, independent of habitat destruction, is not always so clear (e.g., Simberloff 2000. What do we really know about fragmentation? Texas Journal of Science 52: S5-S22).The biological dynamics of forest fragments project (BDFFP) in the Amazon, was started in 1979 and created 11 tropical forest patches ranging from 1 to 100 ha in size. The dynamics of these fragments have been consistently monitored and compared to plots in intact forest. This experiment represents the world's largest, longest-running fragmentation experiment and has told us more about fragmentation then any other study system. In a recent publication by William Laurance and many colleagues involved in this project, they summarize 30 years of data and show how fragmentation affects ecological patterns and processes.Fragments turn out to be very dynamic and defined by change, compared to interior plots. They have higher tree mortality and are much more susceptible to weather events such as storms or droughts. The effects are especially pronounced at the edges of these fragments. The edge community face high mortality but also have higher tree density. Faunal communities in fragments and especially near edges are depauperate.One interesting aspect highlighted by this 30 years of research is that the edge effects are strongly influenced by what is happening around the fragments. The fragment edge effects are sensitive to the composition of the inter-patch matrix, giving managers the opportunity to influence fragment diversity and health by managing the matrix in ways that support fragments. Because of over 30 years of perseverance of the researchers involved, this experiment give scientists, managers and policy-makers information to help manage an increasingly fragmented world and to find ways to reduce to negative impacts of habitat destruction.Laurance, W., Camargo, J., Luizão, R., Laurance, S., Pimm, S., Bruna, E., Stouffer, P., Bruce Williamson, G., Benítez-Malvido, J., & Vasconcelos, H. (2010). The fate of Amazonian forest fragments: A 32-year investigation Biological Conservation DOI: 10.1016/j.biocon.2010.09.021... Read more »
Laurance, W., Camargo, J., Luizão, R., Laurance, S., Pimm, S., Bruna, E., Stouffer, P., Bruce Williamson, G., Benítez-Malvido, J., & Vasconcelos, H. (2010) The fate of Amazonian forest fragments: A 32-year investigation. Biological Conservation. DOI: 10.1016/j.biocon.2010.09.021
As ecological systems are altered with cascading changes in diversity, the oft-asked question is: does diversity matter for ecosystem function? This question has been tested a multitude of times, with the results often supporting the idea that more diverse assemblages provide greater functioning (such as productivity, nutrient cycling, supporting greater pollinator abundance, etc.). Besides greater functioning, scientists have hypothesized that more diverse systems are inherently more stable. That is, the functions communities provide remain more constant over time compared with less diverse systems, which may be less reliable.While the relationship between diversity and stability has been tested for some functions, Proulx and colleagues examined the stability of 42 variables over 7 years across 82 experimental plots planted with either 1, 2, 4, 8, 16 or 60 plant species in Jena, Germany. They examined patterns of variation (and covariation) in the functions and found that many show lower variation over time in plots with more plant species. Greater stability was found at many different trophic levels including plant biomass production, the abundance and diversity of invertebrates and the abundance of parasitic wasps -which indicate more complex food webs. They also found greater stability in gas flux, such as carbon dioxide. Despite the greater stability in these measures of above-ground functions, below ground processes, such as earthworm abundance and soil nutrients, were not less variable in high diversity plots.How ecosystems function is of great concern; these results show that more diverse plant communities function more stably and reliably than less diverse ones. The next step for this type of research should be to address what kind of diversity matters. A greater number of species means more different kinds of species, with differing traits and functions. What aspect of such functional differences determine stability of ecosystem function?This is an exciting paper that continues to highlight the need to understand how community diversity drives ecosystem function.Proulx, R., Wirth, C., Voigt, W., Weigelt, A., Roscher, C., Attinger, S., Baade, J., Barnard, R., Buchmann, N., Buscot, F., Eisenhauer, N., Fischer, M., Gleixner, G., Halle, S., Hildebrandt, A., Kowalski, E., Kuu, A., Lange, M., Milcu, A., Niklaus, P., Oelmann, Y., Rosenkranz, S., Sabais, A., Scherber, C., Scherer-Lorenzen, M., Scheu, S., Schulze, E., Schumacher, J., Schwichtenberg, G., Soussana, J., Temperton, V., Weisser, W., Wilcke, W., & Schmid, B. (2010). Diversity Promotes Temporal Stability across Levels of Ecosystem Organization in Experimental Grasslands PLoS ONE, 5 (10) DOI: 10.1371/journal.pone.0013382... Read more »
Proulx, R., Wirth, C., Voigt, W., Weigelt, A., Roscher, C., Attinger, S., Baade, J., Barnard, R., Buchmann, N., Buscot, F.... (2010) Diversity Promotes Temporal Stability across Levels of Ecosystem Organization in Experimental Grasslands. PLoS ONE, 5(10). DOI: 10.1371/journal.pone.0013382
*note: this text was adapted from an Editor's Choice I wrote for the Journal of Applied Ecology.In this era of species loss and habitat degradation, understanding the link between biodiversity and functioning of species assemblages is a critically important area of research. Two decades of research has shown that communities with more species or functional types results in higher levels of ecosystem functioning, such as nutrient processing rates, carbon sequestration and productivity, among others. This research has typically used controlled experiments that standardize environmental influences and manipulate species diversity. However, a number of people have hypothesized that biodiversity may be even more important for the maintenance of ecosystem functioning during times of environmental stress or change rather than under stable, controlled conditions. It is during these times of environmental change that preserving ecological function is most important, as changes in function can have cascading effects on other trophic levels, compounding environmental stress. Therefore, explicitly testing how biodiversity affects function under environmental stress can help to inform management decisions. Image from Wikimedia commonsIn a recent paper in the Journal of Applied Ecology, Li and colleagues examine how algal biodiversity influences productivity in microcosms with differing cadmium concentrations. Cadmium (Cd) is a heavy metal used in a number of products and industrial processes, but it is toxic and Cd pollution is a concern for human populations and biological systems, especially aquatic communities. This is especially true in nations currently undergoing massive industrial expansion. In response to concerns about Cd pollution effects on aquatic productivity, Li et al. used algal assemblages from single species monocultures to eight species polycultures grown under a Cd-free control and two concentrations of Cd, and measured algal biomass. Their results revealed that there was only a weak biodiversity-biomass relationship in the Cd-free teatment, which the authors ascribed to negative interactions offsetting positive niche partitioning. In particular, those species that were most productive in their monocultures were the most suppressed in polycultures. However, in microcosms with Cd present there were positive relationships between diversity and biomass. They attribute this to a reduction in the strength of competitive interactions and the opportunity for highly productive species to persist in the communities. While a plethora of experiments generally find increased ecosystem function with greater diversity, Li et al.’s research indicates that the effect of biodiversity on function may be even more important in polluted systems. If this result can be duplicated in other systems, then this gives added pressure for management strategies to maintain maximal diversity as insurance against an uncertain future.Li, J., Duan, H., Li, S., Kuang, J., Zeng, Y., & Shu, W. (2010). Cadmium pollution triggers a positive biodiversity-productivity relationship: evidence from a laboratory microcosm experiment Journal of Applied Ecology, 47 (4), 890-898 DOI: 10.1111/j.1365-2664.2010.01818.x... Read more »
Li, J., Duan, H., Li, S., Kuang, J., Zeng, Y., & Shu, W. (2010) Cadmium pollution triggers a positive biodiversity-productivity relationship: evidence from a laboratory microcosm experiment. Journal of Applied Ecology, 47(4), 890-898. DOI: 10.1111/j.1365-2664.2010.01818.x
The basic reality of agricultural activity is that it reduces biological diversity, and these reductions in diversity potentially impact ecosystem services. But do some agricultural practices impact these services less than others? In a recent paper in Nature by David Crowder and colleagues, the question of how organic versus conventional farming affects predator and herbivore pathogen diversity and how this cascades to pest suppression. They show through a meta-analysis, that organic farms tend to support greater natural enemy evenness, and they hypothesize that greater evenness of enemies should better control pest populations, resulting in larger, more productive plants.Picture from wikipediaThis result in itself is interesting, but they also carried out an elegant enclosure experiment where they manipulate the evenness of insect predators and pathogens and measure potato plant size. They found that even communities had the lowest herbivore densities and saw the greatest increases in plant biomass. Conversely, very uneven communities, typical of conventional farms, had the largest pest populations resulting in lower plant biomass accumulation.While, multiple farming strategies are needed for adequate agricultural production, there are strong arguments for organic farms to be a important part of agricultural practice. These results show that organic farms have cascading effects on pest predators and pathogens and show that enemy evenness, as opposed to richness, has important ecosystem service consequences. To quote myself, evenness is a critical component of biodiversity, and much research has emphasized species richness, maybe at the detriment of studying evenness.Crowder, D., Northfield, T., Strand, M., & Snyder, W. (2010). Organic agriculture promotes evenness and natural pest control Nature, 466 (7302), 109-112 DOI: 10.1038/nature09183... Read more »
Crowder, D., Northfield, T., Strand, M., & Snyder, W. (2010) Organic agriculture promotes evenness and natural pest control. Nature, 466(7302), 109-112. DOI: 10.1038/nature09183
Among the numerous and still informative ecological predictions made by Darwin, one posits that when species are introduced into regions where they were not formerly found, the most successful tend to not have close relatives already occupying the region. This is known as Darwin's Naturalization Hypothesis, and his logic was that among close relatives, where ecological requirements should be most similar, the struggle for existence is most severe. Thus the modern formulation is that invader success is influenced by the amount of time since two species shared a common ancestor (usually called phylogenetic distance). Tests of this hypothesis have been primarily done on large species inventories, with results from different studies either supporting or refuting it. In a new study by Lin Jiang and colleagues published in the American Naturalist, they cleverly use bacteria with known relatedness to test this hypothesis.They used four species of bacteria: Bacillus pumilus, B. cereus, Frigoribacterium sp. and Serratia marcescens as residents in every possible 1, 2, 3 and 4-species communities and invaded them with a subspecies of S. marcescens. What they found was that the invader density was highly significantly related to phylogenetic distance, so that the invader reached its greatest density when communities contained only distantly-related species.Though these types of laboratory experiments are simplistic (I too use these systems), they offer insights into particular mechanisms, which may otherwise be difficult to detect in noisier systems.Jiang, L., Tan, J., & Pu, Z. (2010). An Experimental Test of Darwin’s Naturalization Hypothesis The American Naturalist, 175 (4), 415-423 DOI: 10.1086/650720... Read more »
Jiang, L., Tan, J., & Pu, Z. (2010) An Experimental Test of Darwin’s Naturalization Hypothesis. The American Naturalist, 175(4), 415-423. DOI: 10.1086/650720
This past decade has seen a rapid expansion of the use of evolutionary phylogenies in ecological studies. This expansion is largely due to the increased availability of phylogenies, but has resulted in new types of hypotheses and statistics aimed to test the phylogenetic patterns underpinning ecological communities. The main computational tool used has been phylocom, created by Cam Webb, David Ackerly and Steve Kembel, which has its own binaries to be installed on one’s computer. However, a new R package, picante has been created by Steve Kembel and colleagues which runs many of the same routines as in phylocom, but in the R framework, allowing one to tie these analyses in better with other, non-phylogenetic tests. Picante also has a number of features and tests not found in phylocom, including tests of phylobetadiversity and phylogenetic signal using Blomberg’s K.
Thanks Steve for all your hard work and for making these tests available to everyone.
Kembel, S., Cowan, P., Helmus, M., Cornwell, W., Morlon, H., Ackerly, D., Blomberg, S., & Webb, C. (2010). Picante: R tools for integrating phylogenies and ecology Bioinformatics DOI: 10.1093/bioinformatics/btq166
... Read more »
Kembel, S., Cowan, P., Helmus, M., Cornwell, W., Morlon, H., Ackerly, D., Blomberg, S., & Webb, C. (2010) Picante: R tools for integrating phylogenies and ecology. Bioinformatics. DOI: 10.1093/bioinformatics/btq166
Often, species become endangered because of multiple stressors, with habitat destruction taking the prize as the most egregious. However, often what pushes a species into extinction is not the main driver of endangerment. For example, passenger pigeon numbers were decimated by unabated hunting, but the proximate cause of extinction was likely an inability to thrive in low densities. Yet, seldom is the case where a known single species interaction is the primary cause of engangerment and maybe extinction. The northern quoll, Dasyurus hallucatus, is an endangered marsupial predator in Australia. The current major threat to the northern quoll is the invasion of toxic can toads. Quolls, being predators of small mammals, birds, reptiles and amphibians, readily attacks cane toads, which are toxic to quolls. Quoll populations have disappeared from areas invaded by cane toads, and extinction seems almost inevitable.Given that the spread of cane toads into the remaining quoll habitats is inevitable, research, led by Stephanie O'donnell in Richard Shine's lab at the University of Sydney and published in the Journal of Applied Ecology, is underway to train quoll's to avoid cane toads. These researchers feed a subset of captive quolls dead toads laced with thiabendazole, a chemical that induces nausea. They then fitted individuals with radio collars and released these toad-smart quolls as well as toad naive ones. Some toad-naive quolls died quickly, after attacking cane toads. Only 58% of male naive quolls survived, while 88% of toad-smart males survived. While females seemed less likely to attack toads, 84% of naive females survived and 94% of toad-smart females survived!See the video of a toad-smart quoll deciding not to eat a cane toad, its pretty cool.O’Donnell, S., Webb, J., & Shine, R. (2010). Conditioned taste aversion enhances the survival of an endangered predator imperilled by a toxic invader Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2010.01802.x... Read more »
O’Donnell, S., Webb, J., & Shine, R. (2010) Conditioned taste aversion enhances the survival of an endangered predator imperilled by a toxic invader. Journal of Applied Ecology. DOI: 10.1111/j.1365-2664.2010.01802.x
In order to promote the persistence and possible spread of extremely rare plant species, ecologists need to know why a species is rare in the first place. In 1986, Deborah Rabinowitz identified seven forms of rarity, where rarity could mean several things depending on range size, habitat specificity and population sizes. When considering rarity, it often feels intuitive to look for environmental causes for these different forms of rarity. Habitat alteration is an obvious environmental change that affects abundance and distribution, but are rare species generally limited by habitat or resource availability? The alternative cause of rarity could just be that sufficient habitat exists, but that the rare species is simply unable to find or disperse to other sites. An extreme example of this would be the Devil's Hole pupfish which exists at only a single pool. It can survive elsewhere (such as in artificial tanks) but natural dispersal is impossible as its pool is in a desert.Photo taken by Kristian Peters and available through GNU free documentation licenseIn a recent paper by Birgit Seifert and Markus Fischer in Biological Conservation, they examine whether an endangered plant, Armeria maritima subsp. elongata, was limited because of a lack of habitats or if it was dispersal limited. They collected seeds from eight populations and experimentally added these seeds to their original populations and to uninhabited, but apparently appropriate sites. They found that seeds germinated equally well in inhabited and uninhabited sites and seedlings had similar survivorships. They found that variation in germination rates were likely caused by originating population size and that low genetic diversity and inbreeding reduce viability.These results reinforce two things. First is that conserving species may only require specific activities, such as collect and distributing seeds. Here ideas like assisted migration seem like valuable conservation strategies. Secondly, we really need to be doing these simple experiments to better understand why species are rare. If we fail to understand the causes of rarity, we may be wasting valuable resources when try to protect rare species.Seifert, B., & Fischer, M. (2010). Experimental establishment of a declining dry-grassland flagship species in relation to seed origin and target environment Biological Conservation DOI: 10.1016/j.biocon.2010.02.028... Read more »
Seifert, B., & Fischer, M. (2010) Experimental establishment of a declining dry-grassland flagship species in relation to seed origin and target environment. Biological Conservation. DOI: 10.1016/j.biocon.2010.02.028
For conservation biology, there are several research thrusts that are of critical importance, and one of these is to find predictors of species' extinction risk. Oft-cited is the particular susceptibility of large-bodied organisms, with their large ranges and slow reproductive rates. But there should be other predictors too, especially within larger mammals. In a forthcoming paper in Global Ecology and Biogeography, Safi and Pettorelli use just a few variables to predict extinction risk in carnivores.They quantified species extinction risk according to the IUCN risk assessments and asked how well three attributes explained variation in extinction risk. They quantified the environmental characteristics of the species' ranges (temperature, precipitation, etc.), spatial distances between species' ranges and the phylogenetic distances among species. Overall, spatial and phylogenetic distances were good predictors of threat status -generally predicting between 21-70% of variation in extinction risk, whereas the environmental variables were weaker predictors. Full models incorporating all three variables (and accounting for their covariance), were able to explain upwards of 96% of the variation in extinction risk!Although these variables do not represent causal mechanisms of extinction risk -rather they are correlative, they do provide conservation biologists with a rapid assessment tool to evaluate extinction risk. These tools should be particularly important in cases were population data are lacking and immediate pragmatic decisions are required.Safi, K., & Pettorelli, N. (2010). Phylogenetic, spatial and environmental components of extinction risk in carnivores Global Ecology and Biogeography DOI: 10.1111/j.1466-8238.2010.00523.x... Read more »
Safi, K., & Pettorelli, N. (2010) Phylogenetic, spatial and environmental components of extinction risk in carnivores. Global Ecology and Biogeography. DOI: 10.1111/j.1466-8238.2010.00523.x
Applied ecology is the science of minimizing human impacts and of supporting ecological systems in an economic landscape. Often though, applied ecologists work in isolation from those economic forces shaping biological landscapes, not really knowing what businesses would like to accomplish for habitat protection or sustainability. At the same businesses are seldom aware of the knowledge, tools and insight provided by ecologists. And perhaps, greater interaction could help turn ecology into a science with direct impact into how human activities proceed and how we manage the impacts of those activities.This is the premise of a paper by Paul Armsworth and 15 other authors on the ecological research needs of business, appearing in the Journal of Applied Ecology (for an interview with Paul, by yours truly, please go to the podcast, and I should point out that I am an Editor with this journal). The authors include academics, NGOs and industrial representatives, and they've come together to analyze patterns of cooperation and to discuss ways forward.They reviewed papers appearing in the top applied ecology journals and grant proposals to the National Environmental Research Council (NERC) in the UK to measure the degree and type of interaction between ecologists and different industries. Ten to 15 percent of publications in applied journals showed some business involvement -mostly from the traditional biological resource industries (farming, fishing and forestry). Further, 35% of NERC proposals included some business engagement, but only 1% had direct business interaction.Further, the authors reported on a workshop where ecologists and business representatives discussed a number of topics. This included how to minimize negative biodiversity impacts and for industries, such as mining, to consider ecosystem function, and how to develop new ecologically-based economic opportunities, such as insurers managing environmental risk. While there were some challenges identified (such as differing time frames of business needs versus scientific research), the authors note the positive atmosphere and the spirit of collaboration.The research in this paper should be emulated elsewhere. A better understanding of business needs and desires can only inform and offer opportunities for applied ecological research. Top-down governmental regulation can only take conservation and ecosystem management so far and those who are directly involved in altering and managing ecosystems must articulate goals and desires in order to successfully apply ecological principles to biodiversity protection in an economic landscape.Armsworth, P., Armsworth, A., Compton, N., Cottle, P., Davies, I., Emmett, B., Fandrich, V., Foote, M., Gaston, K., Gardiner, P., Hess, T., Hopkins, J., Horsley, N., Leaver, N., Maynard, T., & Shannon, D. (2010). The ecological research needs of business Journal of Applied Ecology, 47 (2), 235-243 DOI: 10.1111/j.1365-2664.2010.01792.x... Read more »
First of all, let me apologize for the lack of blog posts over the past 2 weeks, I've been busy visiting the Olympics and reading a couple of hundred blog, judging them for the Research Blogging awards.
The conservation of biological diversity is a major imperative for biologists. International agreements such as the Convention on Biological Diversity and intergovernmental exercises, such as the Millennium Ecosystem Assessment, call upon scientists to provide evidence on the current state of biological diversity and to evaluate solutions for reducing diversity and ecosystem function loss. Critical to these efforts have been the work of ecologists, conservation biologists and ecological economists. However, seemingly missing from the conversation about the state of biodiversity knowledge has been evolutionary biologists. Are they primarily concerned with describing historical processes and mechanisms of biological change, or do they have substantive knowledge and ideas that should be viewed as a critical component of any scheme to conserve biological diversity?
In a recent paper in Evolution, Hendry and a number of coauthors convincingly make the case that evolutionary biology is a necessary component for conservation. Evolution offer four key insights that should inform conservation and policy decisions. First, they point out that evolutionary biologists are in the business of discovering and documenting biodiversity. They are the primary drivers behind long-term, sustained biological collections, because they need to know what exists in order to better understand evolutionary history. With millions of species awaiting scientific discovery, their efforts are critical to measuring biodiversity. But not only are they discovering new species and enumerating them, they are uncovering their evolutionary relationships, which gives conservationists better information about which species to prioritize. What Vane-Wright famously called 'the agony of choice', with limited resources, we need to prioritize some species over others, and their evolutionary uniqueness ought to be a factor. More than this, evolutionary biologists have developed pragmatic tools for inventorying and sharing data on biodiversity at all levels, from genes to species, which is available for prioritization.
The second key insight is that by understanding the causes of diversification, we can better understand and predict diversity responses to environmental and climatic change. By understanding how key functional traits evolve, we can develop predictions about which species or groups of species can tolerate certain perturbations. Further, research into how and why certain evolutionary groups faced extinction can help us respond to the current extinction crisis. For example, the evolutionary correspondence between coevolved mutualists, such as plants and pollinators, can be used to assess the potential for cascading extinctions. These types of analyses can help identify those groups of related species, or those possessing some trait, which make species more susceptible to extinction.
Normal 0 0 1 355 1779 UTSC 36 4 2490 10.265 0 0 0 Thirdly, evolution allows for an understanding of the potential responses to human disturbance. Evolutionary change is a critical part of ecological dynamics, and as environment change can result in reduced fitness, smaller population sizes and extinction, evolution offers an adaptive response to these negative impacts. Knowing when and how populations can evolve is crucial. Evolutionary change is a product of genetic variation, immigration, population size and stochasticity, and if the ability to evolve to environmental change is key for persistence, then these evolutionary processes are also key. Finally, evolutionary patterns and processes have important implications for ecosystem services and economic and human well-being. Both genetic and evolutionary diversity of plant communities has been shown to affect arthropod diversity, primary productivity (including work by me) and nutrient dynamics. Thus understanding how changes in diversity affect ecosystem processes should consider evolutionary processes. Further, exotic species are often cited as one of the major threats to biodiversity, and evolutionary change in exotics has been shown to increase exotic impacts on native species.
All together, these key reasons why evolution matters for conservation, mean that developing sound management plans requires considering evolution patterns and processes. We can use evolution to our benefit only if we understand how evolution shapes current dynamics. The challenge to evolutionary biologists is the same as it was for ecologists perhaps 15 to 20 years ago, to present their understanding and conservation ideas to a broader audience and to engage policy makers. To this end, the authors highlight some recent advances in incorporating evolutionary views into existing biodiversity and conservation programmes –most notably into DIVERSITAS.
Just like ecological processes and dynamics cannot be fully understood without appreciating evolution ancestry or dynamics, developing an extensive, expansive conservation strategies must take into account evolution. I hope that this paper signals a new era of a synthesis between ecology and evolution, which produces precise, viable conservation strategies. ... Read more »
Hendry, A., Lohmann, L., Conti, E., Cracraft, J., Crandall, K., Faith, D., HÃ¤user, C., Joly, C., Kogure, K., Larigauderie, A.... (2010) EVOLUTIONARY BIOLOGY IN BIODIVERSITY SCIENCE, CONSERVATION, AND POLICY: A CALL TO ACTION. Evolution. DOI: 10.1111/j.1558-5646.2010.00947.x
The evolution of negative interactions seems like a logical consequence of natural selection. Organisms compete for resources or view one another as a resource, thus finding ways to more efficiently find and consume prey. However, to me, the natural selection of symbiotic or mutualistic interactions has never seemed as straight forward (expect maybe the case where one species provides protection for the other, such as in ant-plant mutualisms). A specific example is the rise of nitrogen-fixing plants, who supply nutrients to bacteria called rhizobia capable of converting atmospheric nitrogen into forms, such as ammonia, usable to the plant host. Not only has this symbiosis evolved, but has seemed to evolve in very evolutionarily distinct lineages. The question is, what are the mechanisms allowing for this?In a recent paper, Marchetti and colleagues answer part of the question. They experimentally manipulate a pathogenic bacteria and observe it turning into a symbiont. They transferred a plasmid from the symbiotic nitrogen fixing Cupriavidus taiwanensis into Ralstonia solanacearum and infected Mimosa roots with it. Plasmid transfer among distinct bacteria species is common and referred to horizontal genetic transfer (as opposed to vertical, which is the transfer to daughter cells). The presence of the plasmid caused R. solanacearum to quickly evolve into a root-nodulating symbiont. Two regulatory genes lost function, and this caused R. solanacearum to form nodules and to impregnate Mimosa root cells.This extremely novel experiment reveals how horizontal gene transfer can supply the impetus for rapid evolution from being a pathogen to a symbiont. More importantly it reveals that sometimes just a few steps are required for this transition and how distantly-related bacterial species can acquire symbiotic behaviors.Marchetti, M., Capela, D., Glew, M., Cruveiller, S., Chane-Woon-Ming, B., Gris, C., Timmers, T., Poinsot, V., Gilbert, L., Heeb, P., Médigue, C., Batut, J., & Masson-Boivin, C. (2010). Experimental Evolution of a Plant Pathogen into a Legume Symbiont PLoS Biology, 8 (1) DOI: 10.1371/journal.pbio.1000280... Read more »
Marchetti, M., Capela, D., Glew, M., Cruveiller, S., Chane-Woon-Ming, B., Gris, C., Timmers, T., Poinsot, V., Gilbert, L., Heeb, P.... (2010) Experimental Evolution of a Plant Pathogen into a Legume Symbiont. PLoS Biology, 8(1). DOI: 10.1371/journal.pbio.1000280
While an obvious affect of climate change will be changes in the distributions or range sizes of species, more insidious and likely more consequential will be how species interactions are affected by changes in the timing of growth and reproduction. These changes in an organism's life cycle, or phenology, can create mismatches between an organism's need and resource availability or the readiness of coevolved partners -such as plants and pollinators.In an 'Idea and Perspective' paper in Ecology Letters, Louie Yang and Volker Rudolf set out a new framework to examine the effects of phenological shifts on species interactions. They argue that one cannot understand or predict the fitness consequences of a phenology shift without knowing how interacting species' phenologies are also influenced by environmental changes. The consequences of phenological shifts are changes in fitness, and the question is: how would one go about assessing the fitness effects of phenological changes on interactions? This is where this paper really hits its stride. Yang and Rudolf set out a new conceptual framework for studying the fitness consequences of phenological shifts. They make the case that an experimental approach is required to test the three likely scenarios. The first is that there are no changes in phenology -that is, measuring the fitness levels of the two interacting species under stable conditions. Second, you induce an experimental shift in the timing of one of the species. For example, in a plant-herbivore interaction, germinate the plant earlier and when the herbivore normally has access to the plant, the plant will be older. What are the fitness changes associated with this shift? Finally, you can shift the timing of the other species relative to the first. In our example, the herbivore has access to younger plants and again are there fitness consequences?Yang and Rudolf call the full combination of possible fitness effects, across a number of timing mismatches, 'the ontogeny-phenology landscape'. By mapping fitness changes across this ontogeny-phenology landscape, researchers can offer better predictions, on top of just changes in range size or habitat use, about the possible affects of climate change. The obvious question, and Yang and Rudolf acknowledge this, is how to extend two-species ontogeny-phenology to multi-species communities. Of course, extending two-species interactions to communities is a question that plagues most of community ecology, but I think the solution is that researchers who know their systems often have intuition about the major players, and thus those species where phenology shifts should have disproportionate effects on other species. Such species could be the place to start. Another strategy would be a food web type approach, where species are lumped into broader trophic groups and we ask how shifts in certain trophic groups affect other groups.Regardless of how to extend this framework to multispecies assemblages, I see this paper as likely to be very influential. It gives researches a new focus and framework, where specific predictions about climate change can be made.Yang, L., & Rudolf, V. (2010). Phenology, ontogeny and the effects of climate change on the timing of species interactions Ecology Letters, 13 (1), 1-10 DOI: 10.1111/j.1461-0248.2009.01402.x... Read more »
Yang, L., & Rudolf, V. (2010) Phenology, ontogeny and the effects of climate change on the timing of species interactions. Ecology Letters, 13(1), 1-10. DOI: 10.1111/j.1461-0248.2009.01402.x
Research over the past 20 years has shown that plant communities with greater diversity maintain higher productivity, greater stability and support more diverse arthropod assemblages. More recently, several experiments have shown that interspecific diversity (namely genotypic differences) also affects community functioning. Pollination is often considered an essential function, and does plant genotypic diversity affect pollinator diversity and frequency?In a recent paper in PLoS ONE, Genung and colleagues test whether plant genotypic diversity affects pollinator visits. They use an experimental system set-up by Greg Crutsinger that combines multiple genotypes of the goldenrod, Solidago altissima, and record pollinator visits over two years. Experimental plots contained 1, 3, 6, or 12 genotypes of S. altissima. After accounting for differences in abundance, Genung et al. show that as genotypic diversity increases, both pollinator richness and number of visits to the plot significantly increase. This increase is greater than expectations of randomly simulated assemblages combining proportional pollinator visits from monocultures.The previous research at the species-level has made a persuasive rationale to protect species diversity in order to maintain ecosystem functioning. Now, research like this is making a case that there are consequences for not explicitly considering genetic diversity in conservation planning and habitat restoration.Genung, M., Lessard, J., Brown, C., Bunn, W., Cregger, M., Reynolds, W., Felker-Quinn, E., Stevenson, M., Hartley, A., Crutsinger, G., Schweitzer, J., & Bailey, J. (2010). Non-Additive Effects of Genotypic Diversity Increase Floral Abundance and Abundance of Floral Visitors PLoS ONE, 5 (1) DOI: 10.1371/journal.pone.0008711... Read more »
Genung, M., Lessard, J., Brown, C., Bunn, W., Cregger, M., Reynolds, W., Felker-Quinn, E., Stevenson, M., Hartley, A., Crutsinger, G.... (2010) Non-Additive Effects of Genotypic Diversity Increase Floral Abundance and Abundance of Floral Visitors. PLoS ONE, 5(1). DOI: 10.1371/journal.pone.0008711
Disclaimer, this was modified from an editorial I wrote for the Journal of Applied Ecology.In the quest to understand species invasions, we often try to link the abundance and distribution of invaders to underlying ecological processes. For example, oft-studied are the links between exotic diversity and native richness or environmental heterogeneity. Seemingly independently, research into how specific land use or management activities affect invasion dynamics is also fairly common. While both research strategies are of fundamental importance, not often recognized, or at least explicitly studied, is that both ecological patterns and management activities simultaneously affect invasion success. Thus a truly integrative approach to understanding invader success must take into account variation in ecological communities and abiotic resource avalibility as well as land use patterns at multiple spatial scales. Such an approach is necessary if ecologists wish to predict potential invader abundance, spread and impact.Diez et al. Examine how environmental and management heterogeneity interact to influence patterns of Hieracium pilosella (Asteraceae) inasions in the South Island of New Zealand. The spread of H. Pilosella in New Zealand is threatening native habitats (tussock fields) and the livestock grazing industry. Diez et al. Asked how environmental and management regimes affect H. Pilosella abundance and distribution across six large farms on the South Island. This is an interesting and important question, not just because they are examining how human-caused and ecological variation interact to affect H. Pilosella dynamics, but also because these sources are heterogeneity are realized at different spatial scales.Diez et al. show that the abundance and distribution of H. Pilosella was significantly affected by the interaction of habitat type (i.e., short vs. tall tussocks) and farm management strategies (i.e., fertilization and grazing rates). At larger scales, H. Pilosella was more abundant in tall tussock habitats and was unaffected by fertilization, while in short tussocks, it was less abundant in fertilized patches. At small scales, H. Pilosella was less likely to be found in short tussocks with high exotic grass cover and high productivity (measured as site soil moisture and solar radiation). Conversely, in tall tussocks, H. Pilosella was more likely to be found on sites with high natural productivity. Diez et al. were able to tease these complex causal mechanism apart by using Bayesian multilevel linear models, for which they included example R code in an online appendix.While it is a truism in ecology to say that heterogeneity affects ecological patterns, this paper deserves mention because they convincingly show that the spread of noxious exotic plants in a complex landscape, can potentially predicted by understanding the invader success in different habitat types and land management strategies. In their case they show how human activities, which were not designed to affect H. Pilosella, can strongly affect abundance in different habitat types. This type of approach to understanding invader dynamics can potentially arm managers with the ability to use existing land use strategies to predict how and where further invader targeting would be most useful.Diez, J., Buckley, H., Case, B., Harsch, M., Sciligo, A., Wangen, S., & Duncan, R. (2009). Interacting effects of management and environmental variability at multiple scales on invasive species distributions Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2009.01725.x... Read more »
Diez, J., Buckley, H., Case, B., Harsch, M., Sciligo, A., Wangen, S., & Duncan, R. (2009) Interacting effects of management and environmental variability at multiple scales on invasive species distributions. Journal of Applied Ecology. DOI: 10.1111/j.1365-2664.2009.01725.x
Contracting a parasite is bad. But is getting colonized by multiple parasitic species worse? This is an interesting and important question. The host is a resource, which can support a limited number of parasitic individuals, and so how does competition affect parasitic species and host mortality?This was the premise of a recent paper by Oliver Balmer and colleagues, studying trypanosome infection of mice hosts. They engineered two transgeneic strains of the protozoan parasite, Trypanosoma brucei (African sleeping sickness), to fluoresce different colors in order to assess infections. They infected mice with each strain separately and together and measured host survival and parasite density.They found that when both strains were present, they competitively suppressed each other and that the level of suppression depended on the initial density of each strain. One of the strains was more virulent than the other, and infection by both strains reduced mortality by 15% compared to infection by the virulent strain only. This is due to the suppression of the virulent strain by the low virulent strain.The authors argue that strain source and intraspecific genetic diversity can have an important effect on host mortality. I would also argue that understanding interspecific interactions and within-host niche differences, would also be critical.What a cool use of molecular technology to test basic hypotheses about disease ecology.Balmer, O., Stearns, S., Schötzau, A., & Brun, R. (2009). Intraspecific competition between co-infecting parasite strains enhances host survival in African trypanosomes Ecology, 90 (12), 3367-3378 DOI: 10.1890/08-2291.1... Read more »
Balmer, O., Stearns, S., Schötzau, A., & Brun, R. (2009) Intraspecific competition between co-infecting parasite strains enhances host survival in African trypanosomes. Ecology, 90(12), 3367-3378. DOI: 10.1890/08-2291.1
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