Mate choice for indirect benefits displayed by a large ornament: simulations using a neural network

I analysed mate choice for indirect genetic benefits displayed by an ornament theoretically by means of a neural network model. In particular, the fitness of a choosy female was compared to that of a nonchoosy one under various ecological conditions such as variation in ornament size between males, the cost of searching, the heritability of the ornament and a correlation between ‘good genes’ and the phenotypic expression of the ornament. Females were allowed to choose between either six or 43 males with ornaments of various sizes. They were allowed to compare males until the largest of the presented males was chosen. I found that choosiness was favoured with increasing variation in ornament size between males, combined with a high heritability of the ornament, a very high correlation between the ‘good genes’ and the phenotype, and low search costs. In general, as the correlation between the ‘good genes’ and the phenotype decreased the variance in expected fitness of choosy females increased. The results suggest that the conditions favouring this type of mate choice are restrictive and apply only to a small set of species.