Animals frequently make sacrifices that may benefit other members of their species. Evolutionary considerations suggest that such altruistic behaviors are especially likely to be evident in the interactions of close genetic kin. Because kin descend from the same ancestors, they possess many genes in common. By aiding their close relatives, individuals thus can propagate copies of their own genes. A prediction of this theory is that organisms should discriminate, where possible, between their close kin and other members of their species, and they should direct beneficial acts primarily toward their close relatives. An understanding of the mechanisms by which animals recognize their kin is important for evaluating theories of the origin and evolution of social behavior. Dr. Waldman is investigating how kin-recognition abilities develop in vertebrates. Because their developmental patterns are well understood, amphibian larvae are excellent animals for exploring factors influencing development. Dr. Waldman will study the responses of tadpoles that are exposed as embryos to various artificial odorants to determine whether or not early experience of environmental factors has long-lasting behavioral effects. Of course, embryos are normally in contact with maternal factors during early development, and cues important for developing kin-recognition abilities may be acquired from the mother. By transplanting ovaries between genetically unrelated females, and later testing the behavioral responses of the foster-siblings thus created, Dr. Waldman will examine the extent to which the mother influences the development of kin-recognition abilities in her offspring. To see if individuals may learn the odors of their siblings at later stages in development, tadpoles will be reared individually in special containers. They will be exposed to water conditioned by either their siblings or non- siblings, and their subsequent behavioral responses will be recorded to determine whether or not individuals can be induced to recognize non-kin rather than kin if they are previously exposed to their odors. This study should demonstrate how the development of kin- recognition abilities results from the interaction of genetic and non-genetic factors. The results may provide insight into how higher vertebrates acquire the ability to recognize their relatives. Moreover, the results should strengthen our under- standing of how nepotistic behaviors evolve in vertebrate populations.
