Handsome birds breed better

摘要

Beauty is only skin deep, so they say. But in a study of the collared flycatcher, researchers in Sweden have shown that the male's sexual ornamentation is a reliable guide to his genetic fitness and suitability as a mate. They say that this result is likely to apply to a wide range of species. The idea that secondary sexual characteristics—the fantail of a peacock, for instance—directly reflect the genetic benefits that a male confers on his offspring is controversial. The idea is hard to test because it is often impossible to tell whether fit offspring owe their success to inheritance, or to environmental factors such as plentiful food.