Polyandry in coal tits Parus ater: fitness consequences of putting eggs into multiple genetic baskets.
Females of many species mate with multiple males within a single reproductive cycle. One hypothesis to explain polyandry postulates that females benefit from increasing within-brood genetic diversity. Two mechanisms may render sire genetic diversity beneficial for females, genetic bet-hedging vs. non-bet-hedging. We analysed whether females of the socially monogamous coal tit (Parus ater) benefit via either of these mechanisms when engaging in extra-pair (i.e. polyandrous) mating. To obtain a measure of within-brood genetic diversity as a function of paternal genetic contributions, we calculated a sire diversity index based on the established Shannon-Wiener Index. In 246 broods from two consecutive years, sire genetic diversity had no effect on either the mean or the variance in brood fitness measured as offspring recruitment within 4 years after birth. The hypothesis that benefits of increasing sire diversity contribute to selection for female extra-pair mating behaviour in P. ater was therefore not supported.
Schmoll
T
T
Institute for Evolutionary Biology and Ecology, University of Bonn, Bonn, Germany. tschmoll@evolution.uni-bonn.de
Schurr
F M
FM
Winkel
W
W
Epplen
J T
JT
Lubjuhn
T
T
D000818:Animals; D005260:Female; D014644:Genetic Variation; D008297:Male; D010063:Ovum / Q000502:physiology; D046109:Passeriformes / Q000235:genetics / Q000502:physiology*; D012098:Reproduction / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology*