Genetic relationship between Litopenaeus setiferus (L.) and L. schmitti (Burkenroad) determined by using 16S mitochondrial sequences and enzymatic analysis

Genetic differentiation and variability data of two populations of two species of shrimp (Litopenaeus setiferus (L.) and L. schmitti (Burkenroad)) have been obtained by electrophoretic analysis and by analysis of 16S mitochondrial DNA. Using eight polymorphic enzymes, the genetic distance (GD) between the two species was 0.165. The GD between L. setiferus populations was 0.0057 and between L. schmitti populations it was 0.0034. The greatest differentiation was found within, rather than between, populations, although the differentiation value between Mexican and Cuban populations varied in accordance with the geographic distance and ecological characteristic of each. We found a high similarity between these two species with a bimodal distribution of the loci with respect to genetic identity. The homology percentages for gene 16S fragments were compared with those from six different shrimp species (L. vannamei, L. stylirostris, Farfantepenaeus notialis, Metapeneopsis lamellata) and Artemia salina. Ninety‐seven percent of identity was found by analysis of a 409 bp of 16S mitochondrial DNA. With these values a phylogenetic tree was made using parsimony criteria. The GDs obtained with this method confirm the classification proposed by Pérez‐Farfante & Kensley (1997) .