DNA microsatellite variability and genetic differentiation among natural populations of the Cuban white shrimp<Emphasis Type="Italic"> Litopenaeus schmitti</Emphasis>

Genetic variability within the Cuban population of the white shrimp Litopenaeus schmitti (Burkenroad, 1936) was assessed using five microsatellite loci and samples collected from four sites (Batabanó, Cienfuegos, Tunas de Zaza, and Manzanillo) from November 1999 to March 2000. All loci were polymorphic, and a total of 80 alleles were found, 13 of them private alleles occurring only in a single population and always in low frequencies. The Cienfuegos sample had the highest observed heterozygosity (H_o=0.653), and the Tunas de Zaza sample had the lowest values (H_o=0.605), but there were no significant differences among samples in heterozygosity or in the mean numbers of alleles per locus (ranging from 11.0 to 11.6). Significant differentiation among populations was detected (F_ST=0.012, P<0.001). Low but significant F_ST values were revealed in pairwise comparisons between populations. Assignation tests correctly assigned high percentages of individuals to their original populations (74.5%) using a Bayesian approach. The significant differentiation among populations could be due to the restriction of gene flow among populations of L. schmitti and is concordant with previous allozyme studies on Cuban populations.Communicated by J.P. Grassle, New Brunswick