Article

Yearling male great tits, Parus major, suffer more strongly from cuckoldry than older males.

Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, D-53121, Bonn, Germany.
Zoology (impact factor: 1.5). 02/2007; 110(5):387-97. DOI:10.1016/j.zool.2007.07.005 pp.387-97
Source: PubMed

ABSTRACT In the majority of socially monogamous bird species, females have offspring sired by males other than their social mate as the result of extra-pair copulations. While it is widely recognised that there is considerable variation in the frequency of extra-pair paternity between species, between populations of a species and between individuals of a population, determinants of this variation are surprisingly difficult to establish. With respect to individual variation within a population, it is an important step to test for male and female correlates of cuckoldry to better understand the patterns as well as the adaptive significance of extra-pair mating behaviour. Here, we analysed patterns of extra-pair paternity in relation to male age, female age and their interaction in the great tit Parus major, a socially monogamous passerine with a moderate frequency of extra-pair paternity. Based on a large sample of 316 genotyped first broods from five successive years, we failed to demonstrate interaction effects of male and female age on both the proportion of extra-pair offspring and the likelihood that at least one extra-pair offspring is present within a brood. However, both the proportion of extra-pair offspring and the likelihood of paternity loss were higher for yearling as compared to older males, while this was not the case for yearling vs. older females. Furthermore, the proportion of extra-pair offspring within a brood decreased with increasing age of the attending male in within-individual analyses. We found a comparable effect also for attending females in within-individual analyses, but only when excluding two individuals with 100% extra-pair paternity. A female (extra-pair) mating preference for older males and/or a limited ability of yearling males to prevent cuckoldry in their broods could explain these age-related patterns of paternity loss. Effect sizes, however, were not particularly large and substantial residual variation within age categories suggests the importance of further yet unidentified determinants of variation in paternity loss in the study population.

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Keywords

100% extra-pair paternity
 
316 genotyped first broods
 
age-related patterns
 
attending male
 
comparable effect
 
Effect sizes
 
extra-pair copulations
 
extra-pair offspring
 
extra-pair paternity
 
female age
 
great tit Parus major
 
interaction effects
 
male age
 
monogamous passerine
 
older females
 
older males
 
one extra-pair offspring
 
paternity loss
 
successive years
 
yearling males
 

Thomas Lubjuhn