The distribution, mechanisms and evolutionary significance of parthenogenesis in oribatid mites

Abstract

Highly derived oribatid mites (Brachypylina) seem to fit most predictions of evolutionary theory regarding the ecological, geographical and taxonomic distribution of parthenogenesis. Earlier derivative groups generally do not. We suggest that the ancestors of large, completely parthenogenetic families (for example, Brachychthoniidae, Lohmanniidae, Camisiidae, Trhypochthoniidae, Malaconothridae, Nanhermanniidae) were themselves parthenogenetic, and that 'speciation' and radiation occurred in the absence of sexual reproduction. Further, it is speculated that automixy (meiotic thelytoky) was the process involved -even though some extant species may prove to be secondarily apomictic, just as apomicts evolve from sexually reproducing lineages. If mechanisms for maintaining heterozygosity are effective, automixy can provide all the advantages of parthenogenesis, plus the DNArepair advantage of meiosis. Genotypes can be diversified by the formation of distinct clones, thereby providing the raw material for successful radiation. The disadvantage of such a system would be its slow rate of change due to the absence of an allele-recruitment mechanism. Much of the above remains speculative since available data are meagre. Future work should include surveys of thelytokous mechanisms in oribatid mites, the genetic characterization of populations of a variety of parthenogenetic and sexual species, and the refinement of hypotheses on phylogenetic relationships of parthenogenetic taxa• Invited paper. R. Schuster et al., The Acari

A screen of maternally inherited microbial endosymbionts in oribatid mites (Acari: Oribatida)

“…Similar to our growing knowledge of microbial diversity in the arthropods, our understanding of the functions and consequences of identified bacteria is also starting to develop (Russell et al, 2012). O. nova is probably the most widespread and most abundant terrestrial arthropod species on Earth (Norton & Palmer, 1991), and the effects of bacterial endosymbionts may have a significant impact on the significant evolutionary success of O. nova.…”

“…An interesting feature of these arthropods is that parthenogenesis is one or two orders of magnitude more common than in most other eukaryotic groups: *10% of all the species reproduce parthenogenetically, presumably by a terminal fusion automixis with holokinetic chromosomes and an inverted sequence of meiotic divisions (Norton & Palmer, 1991;Norton et al, 1993). Several of the old taxa of oribatid mites likely have radiated whilst being parthenogenetic.…”

“…Several of the old taxa of oribatid mites likely have radiated whilst being parthenogenetic. It has assumed that some of the 'lower' Oribatida could restore sexual reproduction: Norton & Palmer (1991) and Dabert et al (2010) have shown that the diverse and primarily sexual mite suborder Astigmata evolved from the group belonging to the thelytokous Macropylina.…”

The invertebrate fauna of anthropogenic soils in the High-Arctic settlement of Barentsburg, Svalbard

“…This could indicate that the Oppiidae (O. neerlandica and O. nova) and the Brachychthoniidae (at least L. brevis and L. sellnicki) were introduced by human activity. They are all parthenogenetic and probably establish more easily than sexual species (Norton & Palmer 1991).…”

Invertebrate fossils from cave sediments: a new proxy for pre-Quaternary paleoenvironments

“…3f, h), two species of the family Oppidae were identified in the sediments of the Trhlovca and Račiška caves. Species of the genus Opiella (sensu lato) can be considered one of the most common arthropod groups on Earth (Norton and Palmer, 1991) with high diversity and abundance in forest litter, also present in shrublands, ecotone zones and grasslands. The new species of Oppiella from the Račiška cave morphologically resembles a species known from modern cave environments.…”