The independent role of morphology in mate choice is revealed by the rare instances where the usual association between song and morphology is disrupted.

Species can be recognized by their morphological characteristics and songs.

Islands are known to differ in the food supply available to ground finches, mainly seeds.

The divergence of songs in the new population away from those in the progenitor population would only be prevented if these processes were balanced by repeated immigration and subsequent breeding: song flow.

Genes that underlie the capacity to receive, use and transmit information are the evolving properties.

Exchange of breeding individuals between two populations tends to homogenize their gene pools.

Thus mating of females was strictly along the lines of paternal song.

Evidence of epistasis from hybridization studies is more scarce.

Closely related species of birds are also chromosomally similar.

The theory of founder effects does not explain how novel features like plumage traits arise.