Quality differences between offspring sired by the social and by an extra-pair partner are usually assumed to have a genetic basis, reflecting genetic benefits of female extra-pair mate choice. In the zebra finch (Taeniopygia guttata), we identified a colour ornament that is under sexual selection and appears to have a heritable basis. Hence, by engaging in extra-pair copulations with highly or...

Males typically have greater variance in reproductive success than females, so mothers should benefit by producing sons under favorable conditions. Being paired with a better-than-average mate is one such favorable circumstance. High-quality fathers can improve conditions for their offspring by providing good genes, good resources, or both, so females paired to such males should invest preferen...

Reproduction is known to increase the basal metabolic rate and generate oxidative stress, a possible proximate cost of reproduction. Carotenoids have been shown to be in vitro antioxidant molecules and, in a number of instances, to contribute in vivo to the antioxidant protection of the organism against the deleterious effects of free radicals and oxidative stress. These compounds are also invo...