Fire increases variance in genetic characteristics of Florida Sand Skink (Plestiodon reynoldsi) local populations.

Fire is a complex event that maintains many ecological systems. The Florida Sand Skink (Plestiodon reynoldsi) is precinctive to Florida Scrub, a habitat that is maintained by infrequent fire. We characterize the effect of fire on genetic diversity and genetic differentiation at eight microsatellite loci in the Florida Sand Skink (n=470) collected from 30 replicate sites over three 'time since last fire' categories at the Archbold Biological Station. Long unburned sites had greater allelic richness and expected heterozygosity than either recently or intermediately burned sites. More recently, burned sites had greater standard deviations of allelic richness and private allelic richness. Expected heterozygosity positively correlated with 'time since fire' (r=0.36, P=0.05) and abundance (r=0.53, P=0.002). There was a significant spatial component to genetic differentiation, and results indicate individuals rarely disperse >1 km. Genetic differentiation was positively correlated with geographic distance in long unburned units (r=0.59, P=0.04), yet this relationship was disrupted by fire in recently (r=0.00, 1) and intermediately (r= -0.81, 0.05) burned areas. Simulations indicate that demographic changes to a local population could have generated the observed differences among 'time since fire' categories. Our findings indicate that infrequent fire may be beneficial to the Florida Sand Skink and that local populations begin to recover from changes attributable to the fire after 10 years. Too frequent fires may reduce genetic diversity because it may take multiple generations for local populations to recover.