9423603 HAIRSTON The magnitude of dispersal between natural populations of organisms is known to affect a wide array of biological events, including speciation, extinction, and local adaptation. The genetic consequence of dispersal, termed gene flow, is commonly inferred from the geographic distribution of gene frequencies. However, the accuracy of such estimates is difficult to ascertain. Measuring gene flow in closely related species which vary in dispersal ability allows such indirect estimates to be evaluated. This proposal outlines a sampling regime for 19 species disperse of Arrenurus water mites across a range of spatial scales. The majority of these species disperse only once in their lifetime on the adult stages of aquatic insects, while a few do not disperse at all. Dispersal ability of the mite species can be ranked categorically based on known attributes of the host and the host-parasite relationship. Analyses of genetic population structure will be made for each mite species from allozyme data, as will the population structure of some insect hosts. Data regarding the insects will provide insight into the genetic consequences of the parasitic association to the parasites. For the water mites, correlations between dispersal and gene flow will be assessed statistically, and phylogenetic relationships will be considered. Because these mites are closely related, occur in similar habitats, and their dispersal potential is well understood, differences between them other than dispersal ability are minimized. This study will be the first attempt to assess population genetic structure in a large group of co-occurring, closely related species.
