Meeting Abstract

15.1  Saturday, Jan. 4 10:30  The effects of predatory lizards on limb-morphology evolution in side-blotched lizards, Uta stansburiana BULA, PA; ZANI, PA*; University of Wisconsin-Stevens Point; University of Wisconsin-Stevens Point pzani@uwsp.edu

Since Arnold (1983) introduced the ecomorphological paradigm numerous studies have demonstrated clear morphology-performance links. However, less clear are the ecological patterns stemming from morphotype-performance-fitness links. To elucidate such patterns we tested the hypothesis that limb dimensions of a prey species vary among populations that differ in predation pressure. To test this hypothesis we studied 22 populations of side-blotched lizards, Uta stansburiana stansburiana, in the northern portion of the species’ range where site differences in types and abundance of predators were evident. Using external markers from standardized photos we measured limb elements in 774 male lizards. As predicted, lizards from sites with lower predator densities had shorter size-relative limbs and limb elements (pes and 4th toe were significantly longer; femur and tibia were marginally longer). However, of the major classes of predators (birds, snakes, predatory lizards), only the densities of predatory lizards explained limb morphology in side-blotched lizards. Moreover, using the number of species of predatory lizards at a site was sufficient to explain limb dimensions. It is presumed that after the last glacial maximum, side-blotched lizards dispersed into the northern portions of the Great Basin and became parapatric to predatory lizards. We postulate that this parapatry reduced the need for the longer limbs associated with greater locomotor performance, thereby selectively favoring the opposing advantages of shorter limbs. We suggest that the strong morphotype-performance link has led to rapid fitness-enhancing morphotypic changes among quasi-continuously distributed populations of side-blotched lizards.