Genetic diversity in thelytokous oribatid mites (Acari; Acariformes: Desmonomata)

The oribatid mite taxon Desmonomata contains the largest known grouping of animals which reproduce by thelytokous parthenogenesis. Considering long-standing views on the fate of thelytokous lineages, their apparent radiation is a paradox, made even more interesting by a general lack of life-history characteristics normally ascribed to thelytokous animals. In addition, existing hypotheses suggest that at least one large sexual mite taxon, the Astigmata, had its origins in this asexual radiation. Electrophoretic data imply that there is no meiotic recombination in most of the species studied, and that rare males are nonfunctional. Compared with one of the sexual species, there is relatively low genetic diversity among the thelytokes, but no case was a population comprised of only one clone. Unlike most other uniparental species, these mites have no close sexual relatives, which means that asexuality is not recent and genetic variability may have arisen since the loss of sex.