Grant: Discovery Grants Program - Individual

This proposal aims to use the modern and fossil record of Western Hemisphere mammals to understand the conditions that have led to the emergence of modern communities, how various drivers have contributed to the evolution of mammal communities, and to develop a baseline for mammal response to biotic and abiotic perturbation. A species' niche or function in an ecological community is an important determinant of where they live, the species with which they interact, their evolutionary “life spans” (i.e., time from origination to extinction), and rates and patterns of speciation and extinction (i.e., whether a species may go extinct or give rise to new species). In my lab, we develop new methods for inferring niches and employ existing methods to explain how niches have shaped the diversity of past and present mammal groups. We then use niche information to understand how modern mammal communities formed and have shaped mammal responses to global change.We will specifically address the role of niche differences in determining the success of Carnivora (cats, dogs, bears, and their relatives) over extinct carnivorous mammals (Creodonts). We will thus answer “what evolutionary conditions led to modern carnivorous mammal assemblages?” and determine the role of creodont niches in their extinction susceptibility.Changes in niche axes are important means by which species respond to perturbation. We will develop antler, a hard tissue with similar composition as bone, as ecological indicators using stable isotopes of carbon, nitrogen, and oxygen. Antlers are shed every year and may therefore provide a high-resolution record of niche axis change in deer and their relatives. We will then use caribou antlers to understand how caribou niches have changed from the late Quaternary to modern using collections at the Canadian Museum of Nature.Classical niche theory predicts that the ways in which species are packed into niche space reflect community assembly mechanisms. Recent studies suggest historical factors are more important than proximate factors in structuring mammal communities. We will develop a new combined fossil and extant mammal dated phylogeny for Western Hemisphere mammals, which will feed studies of phylogenetic and functional diversity change in both present and past mammal faunas. We will specifically use phylogenetic methods to test how species exchange (i.e., dispersal or biotic interchange) and evolutionary mode (i.e., stabilizing selection, Brownian Motion) have contributed to differences in the phylogenetic and functional structure of Western Hemisphere tropical and temperate mammal assemblages in the past and present. Generating useful predictions for the outcome of global change requires the integration of modern observation, forecasting, and fossil data. Our work generates predictions for the impact of global change that directly addresses the role of extinction and evolution.