Frogs and toads recognize their close kin, and behaviorally discriminate between close kin and non-kin. In this study, the investigators will examine the ecological and evolutionary ramifications of kin discrimination in populations of tadpoles and adults of the American toad, Bufo americanus. Kin recognition may enable breeding adults to avoid incest by choosing an unrelated partner for a mate. Kin discrimination is also evident in the schooling behavior of tadpoles, which show preferences to aggregate with their siblings. To examine how these preferences are expressed both in natural and experimental populations, the investigators will determine the genetic relationships among individuals by conducting analyses of DNA extracted from the nuclei and mitochondria using two techniques: restriction fragment length polymorphisms (RFLP's) and analyses of hypervariable nuclear sequences (DNA "fingerprinting"). Frogs and toads are model organisms for studying questions of how and why animals recognize their kin. The results should offer new insight into the ecology and evolution of kin recognition in vertebrates. The results should also have practical ramifications. Deleterious effects on growth and survivorship are often attributable to high levels of inbreeding. As endangered populations decrease in size, inbreeding depression can lead to extinction. Kin-recognition mechanisms may function to ensure optimal levels of outbreeding. Hence, an understanding of these mechanisms may be important for the development of effective plans of conservation. Experimental analyses of the effects of genetic diversity on growth rates offer the promise of leading to new theoretical insights that may ultimately improve harvesting yields, both in agricultural and fisheries projects.
