Communication occurs in many animals, and often involves physical traits that vary among individuals. Such signals affect social interactions in a variety of contexts, but the natural forces shaping the use of signals are not understood. Many aspects of communication, such as providing false information, could be better understood if more was known about the developmental processes involved. Developmental events affect the nature of the signal, and may also influence how others perceive it and respond. For signals, the developmental process could either depend on resources or be socially influenced. This project will test these two mechanisms of development in a bird, the house sparrow, which has a conspicuous signal of competitive ability. The possibility that plumage signals are sensitive to resources will be tested by systematically manipulating diet during molt. Components of the diet, such as particular amino acids or nutrients, will be adjusted independently of each other. A second hypothesis, that social experience of particular types and with partners of particular characteristics influence the development of the signal, will also be tested. In addition, variation in how individuals respond to the signals of others will be measured. The developmental processes that could influence such variation will be investigated by manipulating early social experience and measuring its effects on later responses to the plumage of novel opponents. The results will be important at several levels. First, they will constitute one of the more thorough studies of the possible condition-dependence of a plumage signal, will be the first to test directly that social experience influences the development of signals, and will assess the novel idea that receiver responses could also be sensitive to social experience. The study will integrate functional and developmental approaches in an attempt to devise a more complete ecological theory of communication and to expand understanding of how phenotypic variation can arise.
The proposed activities also have broader impact. The project will advance discovery by integrating across levels of biological organization in ways that have potential effects on several related fields of biology. It will also stimulate a broad program of research training. It will directly support a post-doctoral scholar and at least one graduate student. The proposed activities will also be integrated into broader programs fostering collaborations with faculty and students at primarily undergraduate institutions (e.g., through the KyNSF-EPSCoR and KyNCRR-BRIN programs). Other students (at the graduate, undergraduate, and high school level) will benefit from the research opportunities created by this project. These students will acquire training in all stages of doing research, from devising ideas, collecting and analyzing data, and presenting the results to a wider audience. The project activities will also contribute to labs associated with regular undergraduate courses in the curriculum and provide material for lectures in mid-level classes illustrating the processes involved in behavioral research. Information generated by the project will be disseminated in traditional ways (journal articles, attendance at meetings by all participants), via the web, and through contacts in local schools and organizations. In this way the new knowledge and the training opportunities stimulated by the project will have the widest possible impact.
