Sexual selection, selection load and quantitative genetics of zebra finch bill colour

摘要

Zebra finch (Taeniopygia guttata) bills are sexually dichromatic with males possessing redder bills than females. Males with redder bills have been shown to be preferred as males by females and to produce more offspring in laboratory experiments. In contrast, females with redder bills have suffered higher niortalily and produced fewer offspring. In this paper, I report on a quantitative genetic study of male and female bill colour from a cross-fostering experiment. The neritability estimates for billcolour between parents and their biological offspring ranged from 0.23 to 0.58 and all but one of these estimates is significantly greater than zero. The heritabilily estimates between cross-fostered offspring and their non-biological parents.were not significantly different from zero. Likewise, the genetic correlation between male and female bill colour was large (r_g = 0.81) for parents and their biological offspring, but riot for cross-fostered offspring and their non-biological parents. I also demonstrate the extent that the genetic correlation between the sexes can retard the predicted evolution of bill colour and create a selection load that reduces the expected rep reduction of this laboratory population.