40 posts · 37,351 views

Everything ecology and evolutionary biology

Marc Cadotte
40 posts

Martin Nuñez
0 posts

Sort by: Latest Post, Most Popular

View by: Condensed, Full

February 3, 2009
06:43 PM
1,549 views

Local extinctions reveal metacommunity dynamics.

by Marc Cadotte in The EEB and flow

Metacommunity dynamics (i.e., that dispersal limitation among locales creates spatially-contingent community processes) have been in vogue over the past half-decade. Many of the advances in this field have come from theoretical models, computer simulations, artificial laboratory assemblages of micro-organisms (with yours truly being a major offender) and field experiments using small-bodied, short-lived organisms. An oft-repeated criticism has been that the necessary conditions for metacommunity processes are what are manipulated in simulations or lab tests and that simple extinction-colonization dynamics are rarely observed for larger, longer-lived organisms. In a recent paper by Kevin Burns and Christopher Neufeld, high levels of extinction and colonization are shown in patchy communities of woody plants. They sampled 18 islands off the west coast of Canada in 1997 then again in 2007 and found that substantial numbers of local extinction were observed. These results reveal that what we often think of as relatively stable communities (woody plant species) are actually quite dynamic, creating the conditions were metacommunity processes are an important mechanisms driving patterns of diversity. They further show that communities with greater exposure to ocean storms had higher extinction risk and species with hardier leaves were less prone to local extinctions.Kevin C. Burns, Christopher J. Neufeld (2009). Plant extinction dynamics in an insular metacommunity Oikos, 118 (2), 191-198 DOI: 10.1111/j.1600-0706.2008.16816.x... Read more »

Kevin C. Burns, & Christopher J. Neufeld. (2009) Plant extinction dynamics in an insular metacommunity. Oikos, 118(2), 191-198. DOI: 10.1111/j.1600-0706.2008.16816.x

January 14, 2009
07:15 PM
1,487 views

However you skin them, cats have important ecosystem consequences

by Marc Cadotte in The EEB and flow

For disclosure’s sake, I was the editor who handled this paper, and much of this post comes from an editorial I wrote for this paper.Islands experience the greatest impacts from the invasion of non-indigenous species and are also at the forefront of efforts to eradicate problematic species and mitigate negative impacts. Bergstrom et al. elegantly studied the habitat and ecosystem consequences from the eradication of feral cats from Macquarie Island, a subantarctic island and a world heritage site administered by the state of Tasmania, Australia. This island has undergone a series of invasions and both cats and rabbits were introduced in the 19th century. Cat predation resulted in drastic declines in seabird populations, likely causing two extinctions, and thus a cat eradication programme began in 1985 with the last cat killed in 2000. The authors recognized that the feral cats had become fully ingrained in the island food web, and they show that despite the introduction of the Myxoma virus prior to the cat eradication, rabbit populations exploded after the cat removal. These large rabbit populations caused pervasive vegetation changes. The authors sampled plots before and after the eradication and found that vegetation in these plots shifted from large, long-lived plants to smaller, faster growing species, some of which are themselves non-indigenous to the island. Further, satellite imagery revealed that more than one-third of island has since undergone vegetation change, likely resulting in large-scale habitat alterations.What these results show us is that the consequences of species eradication may be complex with unintended results. Non-indigenous predators and meso-predators can become important components of island food webs –so important that their subsequent removal can have repercussions felt throughout the entire food web. While trying to protect seabird populations is undoubtedly worthy of management action (including eradication programmes), adequately predicting ecosystem-level consequences should be the basis directing such activities. Planning for such management activities must include information gained through experimentation, modeling and natural history. By using all available tools and knowledge, management activities can have a better chance of succeeding and harmful unintended consequences minimized.Dana M. Bergstrom, Arko Lucieer, Kate Kiefer, Jane Wasley, Lee Belbin, Tore K. Pedersen, Steven L. Chown (2009). Indirect effects of invasive species removal devastate World Heritage Island Journal of Applied Ecology, 46 (1), 73-81 DOI: 10.1111/j.1365-2664.2008.01601.x... Read more »

Dana M. Bergstrom, Arko Lucieer, Kate Kiefer, Jane Wasley, Lee Belbin, Tore K. Pedersen, & Steven L. Chown. (2009) Indirect effects of invasive species removal devastate World Heritage Island. Journal of Applied Ecology, 46(1), 73-81. DOI: 10.1111/j.1365-2664.2008.01601.x

February 10, 2009
01:23 AM
1,458 views

Stability begets diversity

by Marc Cadotte in The EEB and flow

A classic hypothesis to explain the high diversity found in tropical rain forests, is that areas within the tropics served as a climatic refuges during Pleistocene global climate fluctuations (e.g., ice ages). These refuges beget diversity because they face much lower extinction rates then non-refuges and they are older, allowing speciation events to accrue. This hypothesis has proven controversial as evidence has been circumstantial and circular (i.e., high diversity areas are taken as evidence of a refuge and the outcome of a refuge is high diversity.). This conundrum has been solved by Ana Carnaval, a postdoctoral researcher in Craig Moritz's lab at UC Berkeley, and colleagues. They use patterns of diversity to identify probable refuges and then support several independent hypotheses about refuge effects on patterns of frog diversity. They show 1) that there is higher genetic diversity within and among refuge populations relative to non-refuges. 2) They show a multi-species pattern of recent population expansion in non-refuges from adjacent refuges. 3) The absence of isolating divergence in non-refuges because of a lack of time. Finally, 4) strong phylogenetic patterns of between refuge structure, indicating periods of isolation and divergence. This paper reveals that hypotheses about the origin of species diversity in hotspots can be tested by using genetic divergence below the species level. Not only does this strongly support the spatial refuge hypothesis for tropical diversity patterns but it also elegantly intertwines microevolutionary processes with macroevolutionary patterns. There couldn't have been a more appropriate study published in the week before Darwin's birthday.A. C. Carnaval, M. J. Hickerson, C. F. B. Haddad, M. T. Rodrigues, C. Moritz (2009). Stability Predicts Genetic Diversity in the Brazilian Atlantic Forest Hotspot Science, 323 (5915), 785-789 DOI: 10.1126/science.1166955... Read more »

A. C. Carnaval, M. J. Hickerson, C. F. B. Haddad, M. T. Rodrigues, & C. Moritz. (2009) Stability Predicts Genetic Diversity in the Brazilian Atlantic Forest Hotspot. Science, 323(5915), 785-789. DOI: 10.1126/science.1166955

May 28, 2009
06:27 PM
1,450 views

How long does it take for an ecosystem to recover?

by Marc Cadotte in The EEB and flow

Numerous human activities, such as logging, fishing, pollution and the introduction of exotic species negatively impact ecosystems around the world. These negative impacts mean ecosystems lose species diversity, biomass production, carbon storage, and nutrient uptake. An important question is, how long does it take for ecosystems to recover from perturbations. The answer to this question can inform conservation policy and strategies and could help focus management resources.In a recent PLoS ONE paper, Jones and Schmitz attempt to answer this question by reviewing 240 published studies that examine post-disturbance ecosystem diversity and function. While they report that many ecosystems recover on the order of decades and that this is likely more rapid than previously thought, there are some important caveats. First, is that only about half of the 240 studies report a recovered state and either they were not carried out long enough or there are certain types of disturbances or systems where recovery takes much longer. Second is that there are important differences among habitat types. For example benthic algal recovery to hurricanes or oil spills may take 2-10 years, while the recovery of tree diversity to logging may take 20 to 100 years (or more). Thirdly, different measures of ecosystems general resulted in differing recovery times. For example, bird populations may recover quite quickly to logging (likely because they are migratory), whereas soil microbial communities and processes may take many decades due to changes in the soil environment. Finally, the nature of the disturbance can be an important determinant of time to recovery. Logging and agriculture require the greatest recovery time, while large storms and oil spills appear to require relative little time.While these results may give us a general picture of ecosystem recovery, the data they use highlight the importance of knowing how disturbance type affect recovery and how different ecosystem measures can alter recovery time estimates. Jones, H., & Schmitz, O. (2009). Rapid Recovery of Damaged Ecosystems PLoS ONE, 4 (5) DOI: 10.1371/journal.pone.0005653... Read more »

Jones, H., & Schmitz, O. (2009) Rapid Recovery of Damaged Ecosystems. PLoS ONE, 4(5). DOI: 10.1371/journal.pone.0005653

March 27, 2009
01:47 PM
1,269 views

The evolutionary meaning of autumn colors

by Marc Cadotte in The EEB and flow

As a kid growing up in Ontario, Canada, I have vivid memories of vast expanses of forests set ablaze by their autumn colors. Whole landscapes look like the canvas of a painter whose love of red, orange, gold and yellow are readily apparent. But, like most biologists, I had been taught that these colors are simply the by-product of leaf senescence, nothing more than a biochemical accident. I was amazed to read Marco Archetti's recent work showing that there may actually be adaptive benefits to changing leaf color in autumn and for particular colors. Generally the adaptive benefits involve either protection against abiotic factors or as a response to plant-animal interactions. One of his interesting results is that autumn coloration has evolved repeatedly and cannot be explained by being related to an ancestor who changed colors, rather that there must be some other evolutionary or adaptive explanation. While he suggests a large number of candidate hypotheses, some more plausible than others, I'll list five for example:1) Sunscreen: Pigments provide photoprotection against photooxidation during the recovery of nutrients.2) Leaf warming: Colors absorb light and warm the leaves during cooling temperatures.3) Coevolution: Tells overwintering insects that the tree is not suitable (poisonous or low nutrition) for hibernation.4) Camouflage: Many insects lack red photoreceptor, making leaves difficult to see -thus protecting trees from overwintering pests.5) Unpalatability: Pigments (e.g., red -anthocyanins) are unpalatable.So, we may quibble about particular hypotheses, but the point for me is that there may be deeper explanations as to why certain species produce the vivid colors they do. At a minimum, Archetti provides amunition to experimental botnists and evolutionary biologists for testing new hypotheses. I'll never look at an autumn forest the same again.Archetti, M. (2009). Classification of hypotheses on the evolution of autumn colours Oikos, 118 (3), 328-333 DOI: 10.1111/j.1600-0706.2008.17164.xArchetti, M. (2008). Phylogenetic analysis reveals a scattered distribution of autumn colours Annals of Botany, 103 (5), 703-713 DOI: 10.1093/aob/mcn259Archetti, M., Döring, T., Hagen, S., Hughes, N., Leather, S., Lee, D., Lev-Yadun, S., Manetas, Y., Ougham, H., & Schaberg, P. (2009). Unravelling the evolution of autumn colours: an interdisciplinary approach Trends in Ecology & Evolution, 24 (3), 166-173 DOI: 10.1016/j.tree.2008.10.006... Read more »

Archetti, M. (2009) Classification of hypotheses on the evolution of autumn colours. Oikos, 118(3), 328-333. DOI: 10.1111/j.1600-0706.2008.17164.x

Archetti, M. (2008) Phylogenetic analysis reveals a scattered distribution of autumn colours. Annals of Botany, 103(5), 703-713. DOI: 10.1093/aob/mcn259

Archetti, M., Döring, T., Hagen, S., Hughes, N., Leather, S., Lee, D., Lev-Yadun, S., Manetas, Y., Ougham, H., & Schaberg, P. (2009) Unravelling the evolution of autumn colours: an interdisciplinary approach. Trends in Ecology , 24(3), 166-173. DOI: 10.1016/j.tree.2008.10.006

September 25, 2009
10:09 PM
1,232 views

Global warming and shifts in food web strucutre

by Marc Cadotte in The EEB and flow

Predicting the effects of global warming on biological systems is of critical importance for informing proactive policy decisions. Most research so far has been on trying to predict shifts in species distributions and changes in interactions within local habitats. But what many of these studies assume is that the basic biological processes and requirements of the individual species will not change -that is their biology is fixed and they simply need to find the place that best suits them. Not so, say Mary O'Connor and colleagues, in a just-released study in PLoS Biology.O'Connor and colleagues experimentally warmed marine microcosms and tested two alternative hypotheses on food web structure: 1) that productivity increases with warming; and 2) warming increases metabolic rates, thus changing consumer-autotroph (i.e., primary producers) interactions. What they found was that warming indeed altered consumer-autotroph interactions. Warming increased base metabolic rates of consumers, as well as primary production, and the net effect was that food webs shifted towards increasing consumer control (i.e., top-down control).What this research means is that global warming may alter food web interactions by increasing resource needs of organisms as their metabolic rates increase. This may increase the stress on communities and change diversity patterns as increased needs may shift competitive hierarchies or affect autotroph's ability to withstand consumer effects.O'Connor, M., Piehler, M., Leech, D., Anton, A., & Bruno, J. (2009). Warming and Resource Availability Shift Food Web Structure and Metabolism PLoS Biology, 7 (8) DOI: 10.1371/journal.pbio.1000178... Read more »

O'Connor, M., Piehler, M., Leech, D., Anton, A., & Bruno, J. (2009) Warming and Resource Availability Shift Food Web Structure and Metabolism. PLoS Biology, 7(8). DOI: 10.1371/journal.pbio.1000178

March 23, 2009
02:37 PM
1,211 views

Conserve now or wait for the data?

by Marc Cadotte in The EEB and flow

E. O. Wilson, referring to the ethical imperative we should apply to the conservation of life, said “The ethical imperative should be, first of all, prudence. We should judge every scrap of biodiversity as priceless while we learn to use it and to come to understand what it means to humanity” (pg. 351, The Diversity of Life). Although, I would argue we should aim to learn biodiversity’s value, both intrinsic and extrinsic, as opposed to what it solely means to humanity, his point is protect now, study later. The reason being that there is still so much to learn in order to adequately assess the Earth’s biological riches, by the time we inventory and map a fraction of biodiversity, we would have lost numerous unique regions and species. Of course the opposing point of view is that we need detailed information in order to best use limited resources to best protect biodiversity. This is a major philosophical divide. In a recent, important paper by Hedley Grantham and colleagues published in Ecology Letters, the question of how long should we wait to take conservation actions was empirically tested.The authors used simulations based on 20 years of habitat loss data from the biologically-rich Fynbos region of South Africa and knowledge about spatial distribution of Protea diversity. Protea surveys (The Protea Atlas) have been carried out over 20 years, inventorying 40,000 plots and recording 381 species within the Proteaceae. They began their simulations with no information about Protea diversity patterns and included annually increasing knowledge, set against annual habitat destruction. They showed that waiting to make conservation decisions after only 2 years resulted in species loss, because habitat loss far outweighed any advantage to gaining more information. Further, more detailed information did not appear to increase the effectiveness of conservation decisions over cruder habitat-level maps.The philosophical divide between protect now-learn later versus the need for detailed information to maximize resources appears bridgeable. It seems that by just accumulating some rough data may go a long way towards making those important conservation decisions. Of course, the irony is that this study needed 20 years of data to adequately assess this.Grantham, H., Wilson, K., Moilanen, A., Rebelo, T., & Possingham, H. (2009). Delaying conservation actions for improved knowledge: how long should we wait? Ecology Letters, 12 (4), 293-301 DOI: 10.1111/j.1461-0248.2009.01287.x... Read more »

Grantham, H., Wilson, K., Moilanen, A., Rebelo, T., & Possingham, H. (2009) Delaying conservation actions for improved knowledge: how long should we wait?. Ecology Letters, 12(4), 293-301. DOI: 10.1111/j.1461-0248.2009.01287.x

November 25, 2009
10:13 PM
1,172 views

Taking below-ground processes seriously: plant coexistence and soil depth

by Marc Cadotte in The EEB and flow

Some of the earliest ecologists, like Eugen Warming and Christen Raunkiaer, were enthralled with the minutia of the differences in plant life forms and how these differences determined where plants lived. They realized that differences in plant growth forms corresponded to how different plants made their way in the world. Since this early era, understanding the mechanisms of plant competition is one of the most widely-studied aspects of ecology. This is such an important aspect of ecology because understanding plant coexistence allows us to understand what controls productivity in the basal trophic level for most terrestrial food webs. There are a plethora of plausible mechanisms for how plants are able to coexist, and most involve above-ground partitioning strategies (such as different leaf shapes) or phenological differences (such as germination or bolting timing). Yet, below-ground interactions among plants as a way to understand competition and coexistence have been making a strong resurgence in the literature lately. This resurgence has been driven by new hypotheses and technologies.In what is probably the best hypothesis test of the role for below-ground niche partitioning, Mathew Dornbush and Brian Wilsey reveal how soil depth can affect coexistence. They seeded 36 tallgrass prairie species into plot that were either shallow, medium or deep soiled, and asked if species richness and diversity were affected after 3 years. They found that species richness significantly increased with increased soil depth, revealing that deeper soils likely had greater niche opportunities for species. Not only did deeper soils harbor greater richness, but compositions were non-random subsets. The species inhabiting shallow soils were a subset of medium soils, and medium a subset of deep. This means that increasing depth opened new niche opportunities, unique from the ones for shallow soils.This study is the first field-based experiment of soil depth and coexistence, that I know of and the results are compelling. Plant species are segregating below-ground niches, and perhaps we look for other partitioning strategies for species that inhabit the same soil depth.Dornbush, M., & Wilsey, B. (2009). Experimental manipulation of soil depth alters species richness and co-occurrence in restored tallgrass prairie Journal of Ecology DOI: 10.1111/j.1365-2745.2009.01605.xOther notable recent papers on below-ground processes:Bartelheimer, M., Gowing, D., & Silvertown, J. (2009). Explaining hydrological niches: the decisive role of below-ground competition in two closely related species Journal of Ecology DOI: 10.1111/j.1365-2745.2009.01598.xCramer, M., van Cauter, A., & Bond, W. (2009). Growth of N-fixing African savanna species is constrained by below-ground competition with grass Journal of Ecology DOI: 10.1111/j.1365-2745.2009.01594.xMeier, C., Keyserling, K., & Bowman, W. (2009). Fine root inputs to soil reduce growth of a neighbouring plant via distinct mechanisms dependent on root carbon chemistry Journal of Ecology, 97 (5), 941-949 DOI: 10.1111/j.1365-2745.2009.01537.x... Read more »

Dornbush, M., & Wilsey, B. (2009) Experimental manipulation of soil depth alters species richness and co-occurrence in restored tallgrass prairie. Journal of Ecology. DOI: 10.1111/j.1365-2745.2009.01605.x

Bartelheimer, M., Gowing, D., & Silvertown, J. (2009) Explaining hydrological niches: the decisive role of below-ground competition in two closely related species . Journal of Ecology. DOI: 10.1111/j.1365-2745.2009.01598.x

Cramer, M., van Cauter, A., & Bond, W. (2009) Growth of N -fixing African savanna species is constrained by below-ground competition with grass . Journal of Ecology. DOI: 10.1111/j.1365-2745.2009.01594.x

Meier, C., Keyserling, K., & Bowman, W. (2009) Fine root inputs to soil reduce growth of a neighbouring plant via distinct mechanisms dependent on root carbon chemistry. Journal of Ecology, 97(5), 941-949. DOI: 10.1111/j.1365-2745.2009.01537.x

March 22, 2010
09:25 PM
1,118 views

Predicting endangered carnivores: the role of environment, space and phylogeny

by Marc Cadotte in The EEB and flow

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

June 1, 2010
10:00 PM
1,110 views

Experimental test of Darwin's naturalization hypothesis

by Marc Cadotte in The EEB and flow

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

March 6, 2009
03:56 PM
986 views

Salamaders and climate change -impending extinctions?

by Marc Cadotte in The EEB and flow

By the now the evidence of a global frog decline, perhaps even an extinction crisis, has been well documented. But what about salamanders? They are normally less abundant and less-studied compared to frogs, but is there evidence of the same general pattern of declining population sizes? According to Sean Rovito and colleagues, the answer is unfortunately yes. They repeated a plethodontid (lungless) salamander survey done in the 1970’s in Central America and found that many species have declined. In fact they failed to find a couple of previously very abundant species. They also found that species declines were phylogenetically non-random and so these declines may result in the loss of whole clades of species, meaning that the evolutionary history of these salamanders is at risk.The authors attempted to determine the cause of these declines and found that neither habitat loss or the chytridiomycosis fungal disease implicated in other declines explained these salamander declines. The authors hypothesize that these declines are a direct result of climate change –namely changing temperature and humidity. If so, we may be witnessing some of the first extinctions that are directly caused by climate change.S. M. Rovito, G. Parra-Olea, C. R. Vasquez-Almazan, T. J. Papenfuss, D. B. Wake (2009). Dramatic declines in neotropical salamander populations are an important part of the global amphibian crisis Proceedings of the National Academy of Sciences, 106 (9), 3231-3236 DOI: 10.1073/pnas.0813051106... Read more »

S. M. Rovito, G. Parra-Olea, C. R. Vasquez-Almazan, T. J. Papenfuss, & D. B. Wake. (2009) Dramatic declines in neotropical salamander populations are an important part of the global amphibian crisis. Proceedings of the National Academy of Sciences, 106(9), 3231-3236. DOI: 10.1073/pnas.0813051106

April 8, 2010
10:26 PM
975 views

Plant rarity: environemtal or dispersal limited?

by Marc Cadotte in The EEB and flow

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

April 14, 2010
01:28 PM
962 views

Teaching a quoll that cane toads are bad

by Marc Cadotte in The EEB and flow

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

December 16, 2009
09:51 PM
930 views

Parastie competition enhances host survival

by Marc Cadotte in The EEB and flow

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

March 17, 2009
03:58 PM
927 views

Being a clover isn’t always so lucky

by Marc Cadotte in The EEB and flow

Happy St. Patrick’s Day, I thought that covering an article about Trifolium (clover) seemed very appropriate. In a paper by Matthias Schleuning and colleagues, Trifolium montanum is a species in decline in central Germany. They examined the relative threats of habitat fragmentation and degradation on T. montanum’s population dynamics. They found that both degradation and fragmentation were having serious negative impacts. Degraded habitats in this system mean the shift away from nutrient-poor conditions and include the invasion of taller species that are better light competitors. T. montanum is a poor light competitor and maintains larger populations in mown or grazed habitats that keep taller invaders out. This species also faces the double whammy of fragmented habitats resulting in isolated populations. These isolates have lower reproductive output likely due to greater inbreeding and less genetic transfer, via pollinators, among different populations.I always think of Trifolium species as being particularly common and widely distributed, but there are some that are threatened and potentially tell us about the threats faced by imperiled plant populations. In fact, while a number of North American Trifolium species have successfully invaded North America, but T. montanum is not, according to the USDA Plants Database. These results reveal that these negative effects affect plants at different stages of their life cycle (growth to maturity vs. recuitment) and that log-term persistence of these populations requires management activities that ameliorate both of these effects.SCHLEUNING, M., NIGGEMANN, M., BECKER, U., & MATTHIES, D. (2009). Negative effects of habitat degradation and fragmentation on the declining grassland plant Trifolium montanum Basic and Applied Ecology, 10 (1), 61-69 DOI: 10.1016/j.baae.2007.12.002... Read more »

SCHLEUNING, M., NIGGEMANN, M., BECKER, U., & MATTHIES, D. (2009) Negative effects of habitat degradation and fragmentation on the declining grassland plant Trifolium montanum. Basic and Applied Ecology, 10(1), 61-69. DOI: 10.1016/j.baae.2007.12.002

August 25, 2009
06:40 AM
899 views

March of polyploids!

by Marc Cadotte in The EEB and flow

Speciation by polyploidy (see here for a general description of polyploidy) is one of the mechanisms of speciation and evolutionary diversification. We all learn about it in Bio 101, right after allopatry and sympatry. It is thought to be an especially important driver of speciation in plants, and anecdotal evidence, such as the origination of the invasive polyploid, Spartina anglica in the UK in the 1800's, reinforced that view. But how important has been unanswered until now.In a new publication in PNAS by Wood et al. -from the Loren Rieseberg lab (one of the best lab homepages BTW) this questions has been answered. The authors go through all available chromosome counts on the Missouri Botanical Garden's Index to Plant Chromosome Numbers, and assess the proportion of polyploid species. They find that about 15% of all angiosperm speciation events coincided with an increase in chromosome number (and about 30% of fern species). Further, about 35% of all genera contain polyploids. Looking across the phylogeny of major plant groups, they find that all major lineages, except Gymnosperms, have significant proportions of polyploids (again with ferns have the greatest proportion). Polyploidy is a ubiquitous feature of plant diversity and a major driver of plant speciation. And now we can quantify just how important.Wood, T., Takebayashi, N., Barker, M., Mayrose, I., Greenspoon, P., & Rieseberg, L. (2009). The frequency of polyploid speciation in vascular plants Proceedings of the National Academy of Sciences, 106 (33), 13875-13879 DOI: 10.1073/pnas.0811575106... Read more »

Wood, T., Takebayashi, N., Barker, M., Mayrose, I., Greenspoon, P., & Rieseberg, L. (2009) The frequency of polyploid speciation in vascular plants. Proceedings of the National Academy of Sciences, 106(33), 13875-13879. DOI: 10.1073/pnas.0811575106

March 9, 2010
09:44 AM
898 views

Ecology and industry: bridging the gap between economics and the environment

by Marc Cadotte in The EEB and flow

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 »

Armsworth, P., Armsworth, A., Compton, N., Cottle, P., Davies, I., Emmett, B., Fandrich, V., Foote, M., Gaston, K., Gardiner, P.... (2010) The ecological research needs of business. Journal of Applied Ecology, 47(2), 235-243. DOI: 10.1111/j.1365-2664.2010.01792.x

January 5, 2010
12:50 PM
894 views

Predicting invader success requires integrating ecological and land use patterns.

by Marc Cadotte in The EEB and flow

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

October 21, 2009
05:04 PM
877 views

Adaptation and dispersal = (mal)adapted

by Marc Cadotte in The EEB and flow

Ever since Darwin, we often think of organisms as being in a constant battle against other organisms and local environments. Thus natural selection and the resulting arms race results in organisms highly adapted to local conditions and against local antagonists. At the same time, and especially driven by theoretical advances in the 1990's, researchers began to ask how dispersal -that is, the flow of genetic material from elsewhere, can disrupt local adaptation. On the one hand it may provide genetic variation allowing for novel solutions to new difficulties. On the other hand, dispersal may reduce the prevalence of fitness-increasing genes within local populations.In a simple but elegant experiment, Jill Anderson and Monica Geber performed a reciprocal transplant experiment, moving Elliott's Blueberry plants between two habitats. One population was from highland, dryer habitats and the other from moist lowlands. They further evaluated performance in greenhouse conditions. Their results, published in Evolution, show that these two populations have not specialized to local conditions. Rather, due to asymmetric gene transfer, lowland individuals actually performed better when planted in highlands than compared to their home habitat. Further, in the greenhouse trials, lowland species did not perform better under higher moisture conditions. While genetic or physiological constraints may also limit adaptation, Anderson and Geber present a fairly convincing case that gene flow is the culprit.These results reveal that populations may actually be relatively mal-adapted to local conditions, which has numerous consequences. For example, we need to be cognizant of adaptations to particular conditions when selecting populations for use in habitat restoration and when trying to predict response to altered climatic or land-use conditions. Importantly what does this mean for multi-species coexistence? Dispersal seems to limit the ability to adapt, and thus, better use local resources or maximize fitness, making for a better competitor. At the same time, dispersal can offset high death rates, allowing for the persistence of a population that would otherwise go extinct. Understanding how these two consequences of dispersal shape populations and communities is an interesting question, and work like Anderson and Geber's provides a foundation for future studies.Anderson, J., & Geber, M. (2009). DEMOGRAPHIC SOURCE-SINK DYNAMICS RESTRICT LOCAL ADAPTATION IN ELLIOTT'S BLUEBERRY ( ) Evolution DOI: 10.1111/j.1558-5646.2009.00825.x... Read more »

Anderson, J., & Geber, M. (2009) DEMOGRAPHIC SOURCE-SINK DYNAMICS RESTRICT LOCAL ADAPTATION IN ELLIOTT'S BLUEBERRY ( ) . Evolution. DOI: 10.1111/j.1558-5646.2009.00825.x

login

The EEB and flow

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

Why is this post inappropriate?

search

topics

dates

View

Language

Languages to Display

join us!

News