Meeting Abstract
Recent research has indicated that limb-dimension differences among lizards may or may not be the result of phenotypic plasticity. However, previous studies of plastic limb responses in lizards analyzed data at the level of the individual, possibly inflating degrees of freedom. We tested whether 12 populations of side-blotched lizards (Uta stansburiana) that differ in predation pressure and show differences in limb dimensions in the field exhibit phenotypic plasticity in the lab by rearing animals in a common-garden environment. At the end of their first growing season hind limb dimensions were measured on 181 lab-reared male lizards (avg. = 15 per site). Analyses including all individuals reveal that pes and (marginally) 4th toe lengths, as well as total hind limb lengths are positively correlated to total predator density, specifically to the density of other predatory lizards. This result is consistent with previous analyses on field-fresh animals and suggests that limb-dimensions differences among populations are the result of evolution. However, when limb dimensions were averaged for each population and data are analyzed in this more statistically conservative manner, the results indicate no differences among populations. This result contradicts our finding that limb-dimensions differences among populations are the result of evolution and instead supports the role of phenotypic plasticity. Thus, these results do not clearly indicate that limb-morphology differences among populations are due to evolved or plastic responses.
