The effects of rearing conditions on sexual traits and preferences in zebra finches

Abstract

Although theory predicts that females should prefer the highest quality male, female mating preferences within populations often show pronounced variation. What causes and maintains this variation remains poorly understood. This thesis addresses the influence of rearing conditions both on female mating preferences and male advertising signals in the zebra finch Taeniopygia guttata. It reconciles earlier apparently contradicting findings on the relative importance of visual versus acoustic signals by comparing females__ preferences across three commonly used testing contexts. It then goes on using brood size manipulations and operant conditioning tests to ask for the effects of developmental condition on sexual traits and preferences. Birds that were raised in small or large broods differed in adult morphology and physiology and adult behaviour: male advertising song and female mating preferences reflected developmental condition. Moreover, the mating behaviour of poor condition females provides the first experimental evidence of self-perceived attractiveness in animals influencing their partner choice. The results provide strong empirical support for theoretical models of state-dependent mate choice.