64.4 Jan. 7 A comparative analysis of natural and sexual selection in lizards IRSCHICK, Duncan*; MEYERS, Jay; University of Massachusetts at Amherst; University of Massachusetts at Amherst email@example.com
The disparate forces of natural and sexual selection are often examined individually, and typically on single species. The downfall of this approach is that one cannot determine whether the direction and magnitude of both kinds of selection is the same for ecologically different species that co-occur within the same community. Recent syntheses of adaptive radiation have argued that sexual and natural selection, often working in concert, may be key players for shaping adaptive radiations, but this idea necessarily requires information on selection on multiple species. We examined both natural and sexual selection on morphology and two kinds of performance (bite force and sprint speed) on four different species of lizards across an entire year (2005-2006). These four species (Anolis distichus, A. sagrei, A. smargdinus, and Urosaurus ornatus) differ markedly in morphology, habitat use, and behavior, but are similar in body size and overall lifestyle (e.g., arboreal, insect-eating). We found strong evidence for a mosaic of selection pressures on morphology and performance, and there was marked divergence in how selection operated among these different species. Further, there was some evidence that selection was often strong on morphology, but not concomitantly on performance, indicating a disconnect between the two kinds of traits. Our findings point towards a new way of quantifying selection on morphology and performance, namely expanding to a phylogenetic and community-based framework.