Predation and Color Polymorphism in a Fragmented Landscape

Organismal phenotypes can result from a subtle balance between local selective pressures and dispersal across ecological transition zones. A commonly studied example is the influence of predation and substrate heterogeneity on color polymorphism. The Florida scrub lizard ( Sceloporus woodi ) inhabits longleaf pine and sand pine scrub habitats, which contrast in predator abundance and substrate type, within the Ocala National Forest. Using clay models, we measured relative differences in predation rate between the two habitat types and found that predation rate is significantly greater in sand pine scrub. We then quantified differences in dorsal color and reflectance of S. woodi and their degree of substrate matching between habitats using calibrated digital photographs and an Ocean Optics flame spectrometer. Individuals from sand pine scrub, where there is an abundance of open sand, tended to have a higher reflectance than individuals from longleaf pine. Our goal is to combine objective measures of color with relative predation rate to study the role of selective pressures on the process of adaptive divergence. Recent availability of microsatellite data may additionally allow for the assessment of how reduced gene flow drives local adaptation.