Análise genética e morfométrica da estrutura populacional do camarão branco Litopenaeus schmitti (Decapoda , Crustacea) na costa do Rio Grande do Norte, Brasil: uma abordagem em fina escala
Abstract
The natural populations of the white shrimp Litopenaeus schmitti are being threatened by intensive
fishing, habitat destruction and introduction of exotic culture species. This species presents
characteristics related to its distribution and life cycle that may lead to the fine-scale structuring of
its populations. The results obtained in the present work by biometric and microsatellite analysis
indicated the existence of genetic and morphological structure between three populations sampled
off the coast of the State of Rio Grande do Norte. This structuring was more pronounced for
females than males, observing the significant differentiation between Diogo Lopes x Touros and
Diogo Lopes x Baía Formosa. The factors responsible for this differentiation seem to be related to
the habitat and life cycle of the shrimp and the ocean currents. No population was in the Hardy-
Weinberg equilibrium, probably due to the significant heterozygote deficit (FIS=0,212, p<0,05). The
assignment tests indicated a larger inflow of migrants in the Baía Formosa Diogo Lopes direction,
a probable result of the Brazilian Northern Current and the Brazilian North Undercurrent. When the
allelic richness and number of private alleles were compared, it was seen that Diogo Lopes and
Touros presented similar and significantly larger values than those of Baía Formosa, corroborating
the situation of the estuaries that influences each of these populations. The Mantel test did not show
isolation by distance, indicating that the populational structure found is due to genetic and
genotypic differences. The results obtained in the present work show for the first time that Brazilian
shrimp populations may be genetically distinct even with small geographic distances, reinforcing
the particular role of estuaries in the maintenance of this genetic diversity.