LOWER MITE INFESTATIONS IN AN ASEXUAL GECKO COMPARED WITH ITS SEXUAL ANCESTORS

What advantage do sexually reproducing organisms gain from their mode of reproduction that compensates for their twofold loss in reproductiv e rate relative to their asexual counterparts? One version of the Red Queen hypothesis suggests that selective pressure from parasites is st rongest on the most common genotype in a population, and thus genetica lly identical clonal lineages are more vulnerable to parasitism over t ime than genetically diverse sexual lineages. Our surveys of the ectop arasites of an asexual gecko and its two sexual ancestral species show that the sexuals have a higher prevalence, abundance, and mean intens ity of mites than asexuals sharing the same habitat. Our experimental data indicate that in one sexual/asexual pair this pattern is at least partly attributable to higher attachment rates of mites to sexuals. S uch a difference may occur as a result of exceptionally high susceptib ility of the sexuals to mites because of their low genetic diversity ( relative to other more-outbred sexual species) and their potentially h igh stress levels, or as a result of exceptionally low susceptibility of the asexuals to mites because of their high levels of heterozygosit y.