Presentation Title

Why Birds Cheat: Do Female American Redstarts Choose Extra-pair Partners to Increase Offspring Heterozygosity?

Format of Presentation

15-minute lecture to be presented the Saturday of the conference

Location

IB 1015

Start Date

24-3-2018 1:45 PM

End Date

24-3-2018 2:00 PM

Abstract

In many bird species, females form monogamous social bonds with their mates; however, in approximately 75% of these species, females will “cheat” on their partners and sire offspring with extra-pair males. One theory suggests that females genetically similar to their social partners will mate with extra-pair males in order to produce higher quality offspring that are more heterozygous (genetically diverse). Heterozygosity has been linked to traits, such as immune response and feather colouration, that increase reproductive fitness in birds. Our study focussed on the American Redstart (Setophaga ruticilla), which has up to 40% of nestlings fathered by extra-pair males. Breeding males have patches of bright orange feathers produced by carotenoid pigments which may be used by females to determine the sexual attractiveness of the male. The purpose of this study was to determine whether or not American redstart females engage in extra-pair mating to sire extra-pair offspring that are more heterozygous than within-pair offspring. In addition, we investigated the relationship between heterozygosity and carotenoid plumage colouration, a trait associated with fitness in redstarts. Genotype data was previously collected for American redstarts over the years 2004-2011, and was analyzed using R software to determine parameters related to heterozygosity. I used JMP statistical software to examine relationships between the heterozygosity parameters, extra-pair paternity, and carotenoid plumage colouration. Our results should give insight into why female American redstarts chose to have extra-pair offspring with certain males and if these offspring are of higher quality than within-pair offspring.

Department

Biological Sciences

Faculty Advisor

Matthew Reudink

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Mar 24th, 1:45 PM Mar 24th, 2:00 PM

Why Birds Cheat: Do Female American Redstarts Choose Extra-pair Partners to Increase Offspring Heterozygosity?

IB 1015

In many bird species, females form monogamous social bonds with their mates; however, in approximately 75% of these species, females will “cheat” on their partners and sire offspring with extra-pair males. One theory suggests that females genetically similar to their social partners will mate with extra-pair males in order to produce higher quality offspring that are more heterozygous (genetically diverse). Heterozygosity has been linked to traits, such as immune response and feather colouration, that increase reproductive fitness in birds. Our study focussed on the American Redstart (Setophaga ruticilla), which has up to 40% of nestlings fathered by extra-pair males. Breeding males have patches of bright orange feathers produced by carotenoid pigments which may be used by females to determine the sexual attractiveness of the male. The purpose of this study was to determine whether or not American redstart females engage in extra-pair mating to sire extra-pair offspring that are more heterozygous than within-pair offspring. In addition, we investigated the relationship between heterozygosity and carotenoid plumage colouration, a trait associated with fitness in redstarts. Genotype data was previously collected for American redstarts over the years 2004-2011, and was analyzed using R software to determine parameters related to heterozygosity. I used JMP statistical software to examine relationships between the heterozygosity parameters, extra-pair paternity, and carotenoid plumage colouration. Our results should give insight into why female American redstarts chose to have extra-pair offspring with certain males and if these offspring are of higher quality than within-pair offspring.