Abstract
Sexual selection theory posits that ornamental traits can evolve if they provide individuals with an advantage in securing multiple mates. That male ornamentation occurs in many bird species in which males pair with a single female is therefore puzzling. It has been proposed that extra‐pair mating can substantially increase the variance in reproductive success among males in monogamous species, thus increasing the potential for sexual selection. We documented the frequency of extra‐pair paternity and examined its effect on variation in male reproductive success in the mountain bluebird Sialia currucoides, a socially monogamous songbird in which males possess brilliant plumage ornamentation. Extra‐pair paternity was common in our Wyoming study population, with 72% of broods containing at least one extra‐pair offspring. The standardized variance in actual male reproductive success (i.e., the total number of within‐pair and extra‐pair offspring sired) was more than seven times higher than the variation in apparent success (i.e., success assuming that no extra‐pair mating occurred). Success at siring within‐pair and extra‐pair offspring both contributed to the variation in overall male reproductive success. Within‐pair success, however, did not predict a male's level of extra‐pair success, suggesting that males do not sacrifice within‐pair paternity to gain extra‐pair paternity. Calculation of the sexual selection (Bateman) gradient showed that males sire approximately two additional offspring for each extra‐pair mate that we identified. Thus, in this sexually dichromatic species, extra‐pair mating increases the variance in male reproductive success and provides the potential for sexual selection to act.
Paper version not known (Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.