Parasite Resistance in Gila and Yaqui Topminnows

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Hedrick 9807490 Endangered species face many threats including loss of habitat, non-native predators, and hunting. One of the major factors causing the reduction of endangered species are parasites (defined broadly as viruses, bacteria, and other infectious agents). Parasites may have a greater impact when an endangered species is reduced to marginal habitat, has lost genetic variation, or becomes inbred from having small or isolated populations. Here we examine the impact of a non-native parasite on the endangered Gila and Yaqui topminnows. The Gila topminnow is found only in nine native locations in Arizona and the Yaqui topminnow only on the San Bernadino Wildlife Refuge in southeastern Arizona. The Gila topminnow has been the subject of extensive examination both genetically and ecologically. In particular, variation at a major histocompatibility complex (MHC) locus, genes thought to be involved in parasite resisitance in all vertebrates, has been characterized. In this research we will examine whether different populations of the these topminows have different resistance to a non-native parasitic fluke and whether differences are related to variation in the MHC locus. In addition we will examine whether inbred fish have a different susceptibility to the parasite than non-inbred fish. In this way we will be able to determine the genetic mechanisms influencing parasite resistance in this endangered species, generate a model for examining such threats in endangered species and directly address potential treats in these two endangered species.