Microsatellite evolution in sunfish (Centrarchidae)

We describe 10 microsatellite loci from bluegill (Lepomis macrochirus) and discuss their evolution within the Centrarchidae. All of the loci exhibit Mendelian inheritance and are unlinked. While six loci are conserved within the Centrarchidae (found also in pumpkinseed (Lepomis gibbosus) and largemouth bass (Micropterus salmoides)), four have origins outside the family and two predate it by 65-150 million years. The persistence of these loci in fish may be due to a slow rate of sequence divergence within their flanking sequences, estimated at 0.14-0.83% per million years. We examine the number of alleles, heterozygosity, range, modes, and the frequency of the most common allele and find that a two-phased model (TPM) or an infinite alleles-model (IAM) best describes the results, while a stepwise mutation model (SMM) is rejected. Therefore, population differentiation analyses utilizing these microsatellite loci should consider parameters based on the IAM (e.g., F_ST) and not the SMM.