research - foci

Striving towards a better understanding of the origins, distribution, loss, and conservation of biodiversity are common themes in the research conducted in our lab. To that end, we use a variety of approaches/resources to collect and analyze our data, including lab experiments, field surveys, museum collections, and comparative methods. For a flavour of our interests, here are the abstracts of three papers:

Wohlfahrt B* & Vamosi SM. 2009. Antagonistic selection or trait compensation? Diverse patterns of predation-induced prey mortality due to the interacting effects of prey phenotype and the environment. Evolutionary Biology 36: 386-396.
Differentiation among closely related prey species may result from differing adaptations to heterogeneous environments. Many studies have focused on competition for shared resources as a major factor promoting differentiation, with considerably less attention focused on interacting effects of abiotic factors and predator-prey relationships. To further investigate the effects of interacting selective factors on the outcomes of mortality and survival in aquatic prey, we conducted interrelated laboratory studies examining the effects of water colour and plant density on predator-induced mortality in four dytiscid species (Coleoptera: Dytiscidae) that varied in body size (total body length), and body colouration pattern. Body size was more strongly phylogenetically conserved than colouration pattern, and larger body size generally resulted in decreased predator-induced mortality rates. In contrast, the effectiveness of body colouration patterns in decreasing prey mortality risk depended on water colour and prey body size. In clear water, small and patterned dytiscids had mortality rates equal to medium-sized plain beetles, thereby compensating for differences in mortality risk due to body size differences. Under dark water conditions, small dytiscids experienced higher mortality rates compared to medium-sized dytiscids; however, the effectiveness of colouration patterns in medium-sized beetles decreased to the point that it became detrimental to survival, revealing antagonistic selection. We suggest that colouration patterns are not ubiquitous in prey species and cospecialization in larger size and presence of colouration patterns does not generally result in higher prey survival, because the effectiveness of the two antipredator defences may be restricted to certain phenotype × environment combinations. Our results illustrate how interactions between prey phenotype and variable environmental conditions among habitats dominated by the same predator can lead to adaptive trade-offs, which can increase the number of possible outcomes of predator mediated selection.

> phylogenetic relationships among the four focal dytiscid species:

maculation tree

Vamosi SM, Heard SB, Vamosi JC & Webb CO. 2009. Emerging patterns in the comparative analysis of phylogenetic community structure. Molecular Ecology 18: 572-592. [Invited Review]

The analysis of the phylogenetic structure of communities can help reveal contemporary ecological interactions, as well as link community ecology with biogeography and the study of character evolution. The number of studies employing this broad approach has increased to the point where comparison of their results can now be used to highlight successes and deficiencies in the approach, and to detect emerging patterns in community organization. We review studies of the phylogenetic structure of communities of different major taxa and trophic levels, across different spatial and phylogenetic scales, and using different metrics and null models. Twenty-three of 39 studies (59%) find evidence for phylogenetic clustering in contemporary communities, but terrestrial and/or plant systems are heavily over-represented among published studies. Experimental investigations, although uncommon at present, hold promise for unraveling mechanisms underlying the phylogenetic community structure patterns observed in community surveys. We discuss the relationship between metrics of phylogenetic clustering and tree balance and explore the various emerging biases in taxonomy and pitfalls of scale. Finally, we look beyond one-dimensional metrics of phylogenetic structure towards multivariate descriptors that better capture the variety of ecological behaviors likely to be exhibited in communities of species with hundreds of millions of years of independent evolution.

> partial "regional" pool (A) of diving beetles, a relatively even community (B) & a clustered community (C):

dytiscid trees

Vamosi JC & Vamosi SM. 2008. Extinction risk escalates in the tropics. PLoS ONE 3(12): e3886.

The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change) are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction) and we discuss mechanisms that may reconcile this apparent contradiction.

> map of the threat to vascular plants in the countries of the world:

extinction risk