Population genetics and ecology of Artemia: Insights into parthenogenetic reproduction.

The relative advantages of sexual and parthenogenetic reproduction have long interested biologists and remain a central issue in ecological and evolutionary studies. Recent data on brine shrimp (Artemia) indicate that extensive ecological and genetic divergence occurs in an obligately parthenogenetic lineage. This challenges the belief that parthenogenetic lineages are evolutionary 'dead ends' and that extensive divergence is necessarily linked to recent recruitment from sexual ancestors. The molecular evidence suggests that parthenogenesis in Artemia is relatively ancient, with a single asexual lineage branching from an Old World sexual ancestor approximately five million years ago. Automictic recombination (which can occur in diploid but not polyploid parthenogenetic brine shrimp) appears to play a central role in the long-term maintenance of the parthenogenetic lineage.