Variabilidade molecular sazonal de drosophila mediopunctata (diptera: drosophilidae)

Abstract

Environment fragmentation can result in reduction of biological diversity due to the genetic variability loss through the decline of specimens number in the populations. The decrease in population size can contribute to the population isolation and, therefore, to the restriction of gene flow, which can lead to increase the genetic differentiation among populations and to decrease of genetic variability within population. Accentuated fluctuations in population size can occur in seasonal cycles in response to reproduction ecological specificities linked to resource availability. Drosophila mediopunctata is a species that has a wide geographic distribution in Neotropical Forests and is not associated to humans. The analyses of several genetic markers in natural populations of this species revealed that they are associated with seasonal, altitudinal and latitudinal variation. The aim of this work was to perform a seasonal microsatellite genetic variability analysis in natural populations of D. mediopunctata in order to contribute to the understanding of this species populational dynamics in Araucaria Forest fragments. Eight microsatellite loci were analyzed in 92 individuals collected in two Araucaria Forest areas located in Guarapuava/PR: 60 specimens collected in the Parque Municipal das Araucárias (PMA) (30 in the winter of 2008 and 30 in the spring of 2010), and 32 collected in Guairacá district (GUA) (13 in the spring and 19 in the winter of 2008). It was detected a high genetic diversity and a low populational (Fst= 0.0243) and seasonal (Fst = 0.0249) genetic differentiation. However, the number of exclusive alleles and Nei (1978) genetic distance and identity indicated a certain reproductive isolation among D. mediopunctata populations/subpopulations. The seasonal differentiation in GUA was higher than in PMA (revealed through the Neighbor-Joining analysis) and the within populational variability was higher in PMA than in GUA (Ho = 0.5385 and Ho = 0.5062, respectively). These data allow to suggest that PMA, a conservation park, in spite of having smaller size than GUA, a farm that presents pinion and mate extraction activities, have a more stable population in the genetic point of view due to its higher habitat preservation quality and diversity.