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 michael.hedrick@unt.edu

Physiological vagility (m h^-1) is the ability to move sustainably. We provide a quantitative metric for vagility that incorporates aerobic capacity (VO_2max), body mass, body temperature and the minimum cost of transport (C_min). A meta-analysis of four vertebrate classes was used to test our vagility metric with data for dispersal distance (D_max) and body mass. We also tested our metric with data for genetic heterogeneity (F_ST^‘) 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 VO_2max. Vagility is higher in reptiles at equivalent body masses than amphibians owing to greater VO_2max at higher body temperatures. D_max was significantly related to body mass for amphibians, reptiles and terrestrial mammals, but was not related to body mass for flying birds. Vagility and D_max were correlated and both scaled similarly with body mass. There was a significant negative correlation (P<0.001) between F_ST^‘ and vagility for amphibians with vagility accounting for 56% of the observed genetic heterogeneity. The degree of genetic differentiation with distance (F_ST km^-1) was greater for amphibians compared with reptiles (P<0.001) and likely due to reduced activity duration or lower VO_2max 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.