Evolutionary genetics: evolution of mate choice in the wild.

Qvarnström et al. test whether the preference of female collared flycatchers (Ficedula albicollis) for males with large forehead patches could have evolved as a by-product of selection acting on male patch size. They find that the crucial genetic correlation between female choice and male patch size is not significant, and conclude that preference for large patches must have been shaped directly by selection. However, their use of the patch size of a female's social partner as a measure of choice is incomplete, and will result in low estimates of the potential for direct selection to shape female preference. Their study is therefore unable to resolve the question of how female preference for large forehead patches has evolved.