Evolutionary ecology of parental care: sexual selection, fitness and alternative personalities

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Traditional theories of sexual selection are often based on the assumption that there are substantial genetic (or 'indirect') benefits to be accrued from choosing among potential mates. There is growing empirical evidence, however, that this assumption may not always be valid and that in some systems non-genetic (or 'direct') benefits of mate choice may be more important than previously realised. The overall aim of this study is to conduct the most comprehensive empirical test of direct models of sexual selection in a wild population, using parental care in birds as our model system. Parental care in birds is a good framework for this type of test because birds provide many of the classic examples in sexual selection and parental care provides a scenario where direct benefits may be substantial. For this project we will use an already established, island population of house sparrows, Passer domesticus, which is ideally suited to our needs because we can monitor both lifetime reproduction and survival for all individuals, thereby allowing us to estimate fitness components with unusual precision. For this population we also have a long-term cross-fostered breeding pedigree, which will allow us to estimate the relative roles of a wide range of genetic and non-genetic factors. In addition, we will also test for links between the amount of parental care that a male provides and other aspects of his reproductive behaviour. We are particularly interested, for instance, in whether there is a trade-off between the amount of effort a male expends on parental care and his ability to seek additional sexual partners. Finally, based on the empirical data that we gather, we will build a theoretical model that seeks to explain why different individuals display such different strategies when it comes to the provision of parental care, and explores whether this variation reflects differences in overall 'personality' among individuals.