"Males transmit signals in courtship through behavioral displays."

"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."

"Plumage features constitute a major component of courtship signals."

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

"Thus the genetic basis to the origin of bird species is to be sought in the inheritance of adult traits that are subject to natural and sexual selection."

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

"To summarize, the particular song a male sings, and the behavioral responses of females to song and morphological signals, are not genetically inherited in a fixed manner but are determined by learning early in life."

"Almost nothing is known from hybridization studies about the inheritance of courtship behavior of females, or of their responsiveness to particular male signals."

"Closely related species of birds are also chromosomally similar."

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

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

"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."

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