Divergent evolution of molecular markers during laboratory adaptation in Drosophila subobscura.

The impact of genetic drift in population divergence can be elucidated using replicated laboratory experiments. In the present study we used microsatellite loci to study the genetic variability and differentiation of laboratory populations of Drosophila subobscura derived from a common ancestral natural population after 49 generations in the laboratory. We found substantial genetic variability in all our populations. The high levels of genetic variability, similar across replicated populations, suggest that careful maintenance procedures can efficiently reduce the loss of genetic variability in captive populations undergoing adaptation, even without applying active management procedures with conservation purposes, in organisms that generate a high number of offspring such as Drosophila. Nevertheless, there was a significant genetic differentiation between replicated populations. This shows the importance of genetic drift, acting through changes in allele frequencies among populations, even when major changes in the degree of genetic diversity in each population are not involved.