Getting warmer: Effect of global climate change on distribution of rodentsin Texas

Historically, distributions of plants and animals have shifted with changes in regional and global temperatures. Current predictions from general circ ulation models show changes in level and variation in temperature and rainf all over the next several decades. The magnitude and direction of such chan ges vary regionally. Studies are beginning to show that these changes will impact distribution of species of plants and animals., and, concomitantly, species composition of plant and animal communities. We used geographic inf ormation systems, vegetation models. and general circulation models to pred ict the impact of global climate change (GCC) on the distribution of vegeta tion at a regional scale, the state of Texas. Then we used habitat preferen ces for species of rodents in the state to predict how GCC would impact the ir geographic range and species richness. Our determination of suitable hab itats for species of rodents included an average of 98% of capture points, and we found that suitable habitat averaged 62% of the geographic range of species. Size of habitat-corrected range increased an average of 2- to 3-fo ld under GCC, indicating that rodents were more adaptable to changes in veg etation than were other mammals we studied (e.g., lagomorphs and insectivor es), whose range decreased, but similar to Chiroptera. whose ranges also in creased. Geographic ranges shifted an average of 54% under a warmer, wetter climate and 61% under a warmer, drier climate, resulting in inclusion of a n average of 60% new vegetation associations in the ranges under the former scenario and 64% under the latter scenario. The impact of GCC on rodents i n Texas was greatest under the warmer, drier climatic scenario. Two species , Oryzomys cousei and Microtus mexicanus, were predicted to go extinct beca use their suitable habitats did not occur under GCC. These results demonstr ated that the type of climate change (warmer, drier or warmer, wetter) and its severity would be important. GCC was predicted to have the greatest imp act on rodent distributions in eastern Texas under a scenario of a warmer a nd wetter climate because forests expanded, whereas the impact would be gre atest in western and southern Texas if climate becomes warmer and drier bec ause desert and shrub habitats expanded. Life-history variables (e.g., habi tat type or diet) were correlated with changes in size of range, location, or habitat composition, and reflected broad changes in the relative distrib ution of vegetation types. Granivores and herbivores used fewer new habitat associations that entered Texas after GCC than did omnivores or insectivor es, as did terrestrial rodents compared with fossorial or arboreal rodents.