Meeting Abstract

P3.83  Sunday, Jan. 6  Contrasting responses to 100 years of climate change: Jaw morphology of two montane chipmunks ZELDITCH, M. L.*; SWIDERSKI, D. L.; Univ. of Michigan, Ann Arbor; Univ. of Michigan, Ann Arbor dlswider@umich.edu

Global warming has had pronounced effects on species’ ranges and timing of reproductive events, but its effects on phenotypes are not yet well documented. Morphological traits might show temperature-related trends, but they could instead show more idiosyncratic temporal patterns due to the fact that whole communities do not track the environments in concert nor do all interacting species change their phenologies concordantly. Consequently, species now may inhabit novel biotic environments, and their phenotypic changes these may be unpredictable from any single abiotic or biotic environmental variable. We compare phenotypic changes in two species of chipmunks, the alpine chipmunk (Tamias alpinus) and lodgepole chipmunk (T. speciosus) from the Sierra Nevada mountains. The samples comprise individuals that were collected by Grinnell and colleagues in 1915 and those collected by the Grinnell Resurvey Project in 2004-2007. Over that century, the alpine chipmunk has undergone a severe range contraction and exhibits increased genetic subdivision; in contrast, the lodgepole chipmunk’s range has been stable and it exhibits no increased genetic subdivision. Both species have changed their jaw size and shape significantly over the past 100 years; jaw shape has changed more than jaw size in both species. Despite that commonality, jaw shapes of these species evolve in nearly perpendicular directions: the angle between evolutionary trajectories is greater than 70°. Although phenotypic change appears to be quite rapid in both species that may be due, in part to plasticity, which can produce more change within a single generation than we find within these populations over a 100 years of environmental change.