Microsatellite polymorphism based genetic variation among the natural populations of two sympatric species of Drosophila: D. bipectinate and D. malerkotliana

Background: Drosophila bipectinata and D. malerkotliana are found to be distributed all along the Oriental-Australian continents and have common phylogenetic descent. The genetic divergence of these two species, alongside their distribution zone have been the matter of research and therefore, genetic markers like chromosome inversions and allozyme variants have been considered to establish the nature and extent of variation they have experienced since their speciation. Methods and Results: This study for the first time includes microsatellite markers to observe the genetic variations among the seven natural populations of D. bipectinata and six populations of D. malerkotliana. Results pertaining to D. bipectinata indicate that the level of average heterozygosity increases from north to south. Similar analysis carried out with D. malerkotliana also showed an increase in the level of average heterozygosity from north to south. Distinct genetic differentiation has been observed between north and south populations of both the species that give an indication that north and south populations have undergone genetic structuring due to absence of gene flow between them and varying environmental conditions of the two geographical zones. Based on the frequencies of microsatellite variants of the two species, we have computed the level of variation between these two species also. Conclusions: The analysis in this regard shows almost similar trend of genetic variation being experienced by these two species which could be a kind of parallel evolution occurring due to similar ecological niches occupied by them and similar impact of evolutionary forces to the populations studied.