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Interspecific variation in brain size is described as being an adaptive consequence of development and behaviour. Despite growing interest in sex-specific influences on the development of conspicuous traits, little research has focused on investigating sex-specific determinants of brain size. The overall goal of my thesis was to investigate the sex-specific influences on brain size evolution in birds. By measuring endocranial volume from museum specimens, I collected a large sex-specific dataset spanning 106 avian species. In Chapter 2, I found that male brain size was negatively associated with testis size, suggesting that sperm competition may be critical in determining brain size in males. In Chapter 3, I determined that brain size in females is mostly influenced by pair-bond strength and the presence of a male partner, which both ultimately increase reproductive success. Overall, different selective factors appear to influence brain size evolution in male and female birds.
Abdellah, Melissa Leila, "The influence of sperm competition and life-history traits on brain size evolution in male and female birds" (2010). Electronic Theses and Dissertations. 8187.