S 18 - 5 Sexual signals , learning processes and evolution

Examples are given of how the widespread learning processes of sexual imprinting, song learning and song preference learning may affect the evolutionary processes of sexual selection and speciation in birds. They show that sexual imprinting may occur together with perceptual biases, giving rise to preferences for mates with exaggerated traits. Sexual imprinting may also give rise to exaggeration of sexual dimorphism through “peak shift”, a by-product of discrimination learning. Imprinting and song (preference) learning seem responsible for enabling or driving the rapid speciation of some avian brood parasites. The examples highlight the point that learning processes can have a profound impact on evolutionary processes and deserve prominent attention in evolutionary theory.