The origins of marine mites: Interpreting geographical and ecological patterns

28 March 2007

Hypotheses are advanced concerning the origins of non-halacarid mites in the marine environment. The hypothesis that oribatid (ameronothroid) and astigmatid (hyadesioid) taxa have had longer marine associations than their prostigmatid and mesostigmatid counterparts, is supported by contrasting geographical, ecological and taxonomic patterns among these mite groups, in particular by the high species to genus ratios, the general lack of generic representation in the terrestrial environment, and well-established marine trophic links of ameronothroid and hyadesioid mites. A second hypothesis that polar and subpolar genera of marine ameronothroid mites (and possibly hyadesioid mites) originated independently of the tropical genera, is suggested by three distinct latitudinal distributions of the major genera of these groups. A third hypothesis that marine origins were caused by glaciation events in the polar regions and competition in the tropics, is supported by species richness patterns across global latitudes, and the apparent habitat separation between rock-dwelling Antarctic and sedimentbased tropical marine mites. A final hypothesis concerns the basis for the return to land by the Antarctic ameronothroid genus Halozetes.