Microsatellite variation among red snapper (Lutjanus campechanus) from theGulf of Mexico

Allelic variation at a total of 20 nuclear-encoded microsatellites was exam ined among adult red snapper (Lutjanus campechanus) sampled from 4 offshore localities in the Gulf of Mexico. The number of alleles at the 20 microsat ellites ranged from 5 to 20; average (F SE) direct count heterozygosity val ues ranged from 0.148 +/- 0.025 to 0.902 +/- 0.008. No significant departur es from expectations of Hardy-Weinberg equilibrium were found for any locus within samples, and genotypes at pairs of microsatellites appeared to be r andomly associated, i.e., in genotypic equilibrium. Tests of homogeneity in allele distributions among the 4 localities were nonsignificant for 19 of the microsatellites. Allele distribution at microsatellite Lca 43 was heter ogeneous among localities before (but not after) Bonferroni corrections for multiple tests executed simultaneously. Tests of homogeneity in the distri bution of individual alleles at Lca 43 gave similar results: one low freque ncy allele was distributed heterogeneously among samples before, but not af ter, Bonferroni correction. Molecular analysis of variance indicated that m ore than 99% of variation at each microsatellite was distributed within sam ple localities. These results generally are consistent with the hypothesis of a single population (stock) of red snapper in the northern Gulf of Mexic o.