Abstract for presentation at 11th International Congress of Human Genetics

Investigation of selective forces that influence the dynamics of distinct biological processes has been a major research focus of evolutionary biologists for more than a century. Recent studies have used a variety of theoretical arguments to show that mitochondrial (mt) DNA is rarely evolving as a strictly neutral marker and that selection is operating on the mtDNA of many species. However, the vast majority of researchers are not convinced by these arguments because data linking mtDNA variation with phenotypic differences are limited. In this study we questioned whether wild caught Drosophila simulans flies harboring two distinct mtDNA haplogroups (siII and siIII) that were collected in sympatry in 2004 differed in specific life history traits and a key aspect of mitochondrial bioenergetics. Flies harboring siII had greater egg size, and fecundity and recovered faster from cold coma. Flies with siIII mtDNA were more starvation resistant and had higher cytochrome c oxidase activity. Combined these data strongly suggest that the current population subdivision of the mtDNA in Drosophila simulans is due to differences in life history and metabolic traits associated with specific mtDNA haplogroups. The results of this study have significant implications for the use of mtDNA as an assumed neutral marker and show that evolutionary shifts can involve changes in mtDNA despite the small number of genes encoded in the organelle genome.