Genetic Relationships among Populations of Florida Bass

Abstract Florida bass Micropterus floridanus are endemic to peninsular Florida and co-occur with largemouth bass M. salmoides in a natural intergrade zone in the northern portions of the state. In this study, we resolved the genetic population structure among populations of largemouth bass, Florida bass, and their interspecific hybrids from 48 lakes and streams across Florida, and we updated and refined the southernmost boundary of introgression. Nuclear (allozyme and microsatellite) and mitochondrial (restriction fragment length polymorphism) markers produced somewhat different results. Microsatellite genotypes alone and the combination of all nuclear genotypes resolved genetic structure among four regional groups within Florida: (1) northwest, (2) north-central, (3) central-west, and (4) south, central-east, and northeast. Allozyme genotypes alone did not resolve well-defined groups. The distribution of mitochondrial haplotypes suggested that populations from the St. Johns River drainage should be consi...