Molecular systematics and the evolution of parasitic associations of dermanyssoid mites (Acari: Dermanyssoidea).

Abstract

Mites are an extremely diverse group of arthropods, ranking only behind insects in estimated total number of species. Within various mite groups exist species exploiting almost every imaginable habitat, ecological mode, and reproductive strategy. The ancestral form of the Acari is that of a typical arachnid, a free-living predator on other arthropods. Many groups have independently diverged from this lifestyle and become herbivores, fungivores, and hematophagus parasites of vertebrates. One mesostigmatid superfamily, Dermanyssoidea, contains members that have successfully made the transition from predator to parasite, not once, but numerous times throughout their evolutionary history. This dissertation is a phylogenetic study of dermanyssoid mites and the evolution of host associations and parasitism that has occurred throughout its history. High variability and convergence of morphological characters due to parasitic and commensal associations with other organisms have plagued taxonomic and phylogenetic studies of the Dermanyssoidea. This dissertation represents the first use of molecular sequence data to address problems in dermanyssoid systematics. Regions of the repeated nuclear ribosomal DNA array were selected for potential phylogenetic information. A combination of the entire 18S region and domains 1--3 of the 28S gene region were used to examine higher order relationships among five dermanyssine superfamilies and test the monophyly of Dermanyssoidea as currently classified. Two families, Spinturnicidae and Spelaeorhynchidae, both parasites of bats, grouped phylogenetically with another superfamily outside Dermanyssoidea. The remaining dermanyssoid lineages included in the study formed a monophyletic unit. Taxonomic sampling of Dermanyssoidea was expanded to explore the evolution of parasitism across the superfamily. Parasitic lifestyles were found to have evolved a minimum of seven independent times within the Dermanyssoidea, including two independent instances of vertebrate endoparasitism. Phylogenetic relationships within a number of parasitic lineages, including the Macronyssidae, Laelapinae, and <italic> Andreacarus</italic> (Laelapinae), were examined using domains 1--3 of 28S and the entire ITS complex (ITS1, 5.8S, ITS2). Phylogenetic hypotheses were established and host associational and biogeographical patterns were explored within the various groups. The adaptability of dermanyssoid morphology and the ability to utilize a variety of food sources for development and reproduction have been key components to the successful colonization of numerous parasitic niches.