Species and community level responses to climate change

The late Pleistocene offers a unique opportunity to study ecological processes involved in structuring communities because of the climate change engendered by the last glaciation. I quantitatively assessed changes in the distributions of mammals to determine the degree to which species shifted their ranges independently over broad time scales (Lyons, 2003).  Next, I examined changes in community composition over broad time scales and assessed the effect of range shifts on community composition using simulation models. Although there was some degree of turnover in all communities, results indicate that the geographic pattern of community similarity through time was more complex than a strict prediction using independent range shifts would imply (Lyons, 2005). Community turnover was larger than expected only when climate change was large enough to cause species to shift across biogeographic provinces.


My recent work has concentrated on determining whether the way in which species shift their distributions was related to ecological or life history traits (Lyons et al 2010).  In particular, I am interested in whether range shifts differ because of taxonomic identity, body size, topographic heterogeneity and whether the species survived the megafaunal extinction.  We found that variation in body size, topographic relief, and some life history traits such a lifespan were related to the distance a species shifted their distribution (Lyons et al 2010).  However, range shifts do no differ between victims and survivors of the megafaunal extinction (Grund et al. 2012).  A follow up study using regression trees to evaluate the relationships between life history traits and range shifts indicates that species that have larger range shifts are species that have a life history that maximizes lifetime reproductive output for their body size (Lyons and Wagner in prep).  That is, it is not just that larger bodied mammals can shift farther than smaller-bodied mammals.  Small-bodied mammals with “fast” life histories also show large range shifts.