Little boy or little girl? Effect of extrapair paternity and parental quality on brood sex ratio in the Scarlet rosefinch (Carpodacus erythrinus)

0345608 - ÚBO 2011 CZ eng A - Abstract
Poláková, Radka - Schnitzer, J. - Vinkler, Michal - Bryja, Josef - Albrecht, Tomáš
Little boy or little girl? Effect of extrapair paternity and parental quality on brood sex ratio in the Scarlet rosefinch (Carpodacus erythrinus).
Zoologické dny Praha 2010: sborník abstraktů z konference 11.-12. února 2010. Brno: Ústav biologie obratlovců AV ČR, 2010 - (Bryja, J.; Zasadil, P.). s. 171-172. ISBN 978-80-87189-07-8.
[Zoologické dny. 11.02.2010-12.02.2010, Praha]
Institutional research plan: CEZ:AV0Z60930519
Keywords : Scarlet rosefinch
Subject RIV: EG - Zoology
http://zoo.ivb.cz/doc/sborniky/sbornik_2010.pdf

Females of many socially monogamous bird species commonly engage in extra-pair copulations (EPC). Assuming that extra-pair males are more attractive than the female´s social partners and that sons inherit a sexy trait (good genes) from their fathers, sex allocation theory predict that females should bias the sex ratio of their broods towards sons when mated to attractive males. Extra-pair young should therefore be more likely to be males. However malebiased sex ratios of offspring were also associated with females in better body condition, and these high quality (heavy) females were more likely to produce sons („the maternal condition hypotheses“). We tested these two hypotheses in the Scarlet rosefinch (Carpodacus erythrinus), a socially monogamous songbird with high percentage (around 30%) of EPC. We have the following assumptions: (1) females mate to attractive male and they expect to bias offspring production in favour of sons; (2) high-quality females are more likely to produce male offspring; and finally (3) extra-pair chicks are more likely to be males. We found no significant effect of paternity (within-pair versus extra-pair) on the sex of individual offspring. However, we found that high-quality (heavy) females produced more sons than daughters. Our results indicate that Scarlet rosefinch females do not manipulate the primary sex ratio of their offspring in relation to the phenotypic quality of their mate, but it is suggested that they might adjust their brood sex ratio according to their own condition.
Permanent Link: http://hdl.handle.net/11104/0186842