Disrupting evolutionary processes: the effect of habitat fragmentation on collared lizards

Abstract: Humans affect biodiversity at the genetic, species, commu-nity, and ecosystem levels. This impact on genetic diversity is critical, be-cause genetic diversity is the raw material of evolutionary change, in-cluding adaptation and speciation. Two forces affecting genetic variation are genetic drift (which decreases genetic variation within but increases genetic differentiation among local populations) and gene flow (which in-creases variation within but decreases differentiation among local pop-ulations). Humans activities often augment drift and diminish gene flow for many species, which reduces genetic variation in local populations and prevents the spread of adaptive complexes outside their population of origin, thereby disrupting adaptive processes both locally and globally within a species. These impacts are illustrated with collared lizards (Cro-taphytus collaris) in the Missouri Ozarks. Forest fire suppression has re-duced habitat and disrupted gene flow in this lizard, thereby altering the balance toward drift and away from gene flow. This balance can be re