pike

In the northern pike (Esox lucius), females are larger and often more brightly coloured than males

blickwinkel/Hartl/Alamy

Sexual selection, a mechanism of evolution that can drive the appearance of bright feathers and elaborate horns, is often assumed to operate largely among males. But a fresh analysis of the data suggests it is more widespread among females than many researchers expected.

It was Charles Darwin who originally suggested that sexual selection is at work in animals. He emphasised that males often compete against other males for females to mate with – which …