Abstract

The impact of habitat fragmentation on the populational genetic structure was studied in two oyster populations of Crassostrea rhizophorae Guilding 1828 from two regions of the Laguna de Terminos, Campeche Mexico by means of the electrophoretic expression of 10 enzymatic systems of muscle. Genetic frequencies data were processed by using the TFPGA 1.3 program. Samples of the muscle of fifty organisms of each population were used in order to characterize the genotypic expression revealed. The protein polymorphism value was 36.35% (p95) and of 90.90% (p99). The heterozygosis values ranged from 0.2491 for Idh1 to 0.01 for Pt1 with a mean value of He = 0.1044. Fis value average was 0.1574 and Fit value average 0.1727 suggested a heterozygote deficiency. The value average of Fst = 0.0181 indicates that the observed genetic differences correspond to a inter populational variation with moderate endogamy. The number of migrants obtained by the Slatkin equation was of 13.5621 for generation indicates a certain degree of variability among the populations it is consistent with the values of Nei genetic distance. It is concluded that the two populations of Crassostrea rhizophorae here studied reflect sensibility to the adaptive processes that take place due to the genetic discontinuity promoted by the fragmentation of the habitat but still without detriment of their levels of genetic variability and in consequence, they do not reflect at present populational fragility that exposes them to habitat fragmentation

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