DISSERTATION RESEARCH: Offspring Recognition and Brood Parasitism in African Finches: Implications for Signal Mimicry and Diversification

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Offspring Recognition and Brood Parasitism in African Finches: Implications for Signal Mimicry and DiversificationDavid W. Winkler and Justin G. SchuetzCommunication between parents and offspring is widespread among birds. However, the signals that nestlings employ in this dialogue have undergone extreme elaboration in only two families of birds, the Estrildid finches and the brood parasitic Viduid finches. The mouth patterns of estrildid nestlings are incredibly diverse; each species possesses a unique combination of spots, colors, and markings on its palate and tongue. Viduid nestlings, which are raised alongside estrildid host nestlings, have mouth markings that precisely match those of the host species they exploit. Presumably, mimicry occurs because raising parasites is costly and because host parents that discriminate against foreign-looking young are favored by natural selection. However, to date, there is scanty evidence for nestling recognition in estrildids and only a few studies of wild host populations have been undertaken. Previous work suggests that food availability, host learning, and nestling phenotypes may influence whether host parents recognize and reject nestlings. Controlled aviary experiments in combination with fieldwork will help to assess the relative importance of these variables. Captive populations of known-age hosts and parasites have already been established, and research in Tanzania, where a viduid exploits more than one host species, will allow for tests of nestling discrimination. Throughout aviary and fieldwork, variation in nestling morphologies within and across species will be documented. In addition to informing our understanding of offspring recognition behavior, results from this research will provide insight into host-parasite interactions and the processes that affect the evolution of animal signals.