Fragmented landscapes, habitat specificity, and conservation genetics of three lizards in Florida scrub

Dry, sandy scrub habitats of the Florida peninsula represent naturally fragmented remnants of xeric ecosystems that were widespread during the Pliocene and early Pleistocene. This habitat is characterized by high endemism, and distribution of genetic and evolutionary diversity among scrub islands is of compelling interest because Florida scrub is rapidly disappearing under human development. We compare range- wide diversity in mitochondrial cytochrome b sequences for three scrub- associated lizards with contrasting levels of habitat specificity. All species show strong geographic partitioning of genetic diversity, supporting the hypothesis that scrub fauna is highly restricted by vicariant separations. The mole skink ( Eumeces egregius), the least habitat specific, has the lowest phylogeographic structure among the lizards ( phi(st) = 0.631). The mtDNA geneology for E. egregius is not entirely concordant with the five recognized subspecies and supports a link between populations in central Florida ( E. e. lividus) and the Florida Keys ( E. e. egregius) rather than a previously proposed affiliation between northern and southern populations. The Florida scrub lizard ( Sceloporus woodi) is the most habitat specific of the lizards and has the strongest phylogeographic structure ( phi(st) = 0.876). The sand skink ( Neoseps reynoldsi) falls between the mole skink and scrub lizard in terms of habitat specificity and phylogeographic structure ( phi(st) = 0.667). For all three species, networks of mtDNA haplotypes coalesce on two central ridges that contain the oldest scrub. The geographic structure and deep evolutionary lineages observed in these species have strong implications for conservation, including strategies for translocation, reserve design, and management of landscape connectivity.