Meeting Abstract

19.4  Friday, Jan. 4  Physiological vagility, vertebrate dispersal and population genetic structure of amphibians HEDRICK, MS*; HILLMAN, SS; DREWES, RC; HANCOCK, TV; University of North Texas; Portland State University; California Academy of Sciences; Eastern Washington University

Physiological vagility (m h-1) is the ability to move sustainably. We provide a quantitative metric for vagility that incorporates aerobic capacity (VO2max), body mass, body temperature and the minimum cost of transport (Cmin). A meta-analysis of four vertebrate classes was used to test our vagility metric with data for dispersal distance (Dmax) and body mass. We also tested our metric with data for genetic heterogeneity (FST') for amphibians and reptiles. Vagility increased with increasing body mass in amphibians (r2=0.73), reptiles (r2=0.59) and terrestrial mammals (r2=0.81), but was independent of body mass (P=0.99) in flying birds. Within terrestrial locomotors, endothermic mammals have greater vagility at equivalent body masses than amphibians or reptiles owing to greater VO2max. Vagility is higher in reptiles at equivalent body masses than amphibians owing to greater VO2max at higher body temperatures. Dmax was significantly related to body mass for amphibians, reptiles and terrestrial mammals, but was not related to body mass for flying birds. Vagility and Dmax were correlated and both scaled similarly with body mass. There was a significant negative correlation (P<0.001) between FST' and vagility for amphibians with vagility accounting for 56% of the observed genetic heterogeneity. The degree of genetic differentiation with distance (FST km-1) was greater for amphibians compared with reptiles (P<0.001) and likely due to reduced activity duration or lower VO2max at lower operating temperatures. Recent studies with amphibian populations validate our vagility hypothesis. Our results suggest that interspecific differences in vagility resulting from physiological and anatomical phenotypes play a significant role in limiting or enhancing genetic exchange among amphibian populations.