EDWARDS, D.D.; ERNSTING, B.R.; Univ. of Evansville; Univ. of Evansville: Determination Of Parentage And Kinship Relationships Among Symbiotic Water Mites Using RAPD-PCR Profiling

The water mite Unionicola foili is a common symbiont of the freshwater mussel Utterbackia imbecillis. A female-biased sex ratio is characteristic of this species, with most mussels harboring a single male and more than 20 females. The structure of the mating system of U. foili is not well understood, primarily because mating and early larval development occurs exclusively within the confines of its mussel host. Male reproductive success is particularly difficult to elucidate given that males display intrasexual aggression and encounters between males can be fatal. This study employs random amplified polymorphic DNA profiling to address parentage and kinship relationships among populations of U. foili from its host mussel U. imbecillis. We identified three 10-base RAPD primers that show reproducible amplified genetic markers in these infrapopulations. These markers were used to assess kinship relationships among larvae and adults from individual hosts. Parsimony analysis for each of the RAPD-PCR profiles for mites from a single mussel indicated that many of the adults are excluded from being the parents of the larvae. Furthermore, larval mites appear to be more closely related to each other than to any combination of male and female adults. These results suggest that many of the larvae obtained from a host mussel are the progeny of adults that reproduced prior to our sampling period and are no longer present. Future studies will sample and analyze adults and larvae at numerous intervals during the year to further test this hypothesis.