Evidence for cuckoldry in the Great Tit Parus major

Abstract

We estimated the frequency of cuckoldry (the proportion of offspring resulting from extra‐pair copulations) in Great Tits Parus major using heritability estimates based on the resemblance of offspring tarsus‐length to that of their parents. Our results suggest that cuckoldry occurs and may be relatively common in certain years.

Comment

“…; own obs. My data therefore do not support Norris & Blakey's (1989) finding of a significant difference between the heritabilities calculated between single parents and their offspring.…”

“…Higher similarities between offspring and their female parent than between offspring and their male parent have been repeatedly used as evidence for extra-pair fertilizations (EPFs) (Alatalo et al 1984, Norris & Blakey 1989: but see LiQeld & Slagsvold 1989.…”

“…Apart from effects of the environment shared by parents and offspring, there are maternal effects such as egg size and incubation behaviour that could lead to inflated heritability estimates from the regression of offspring on their female parent. Norris & Blakey (1989). however, claim that extra-pair copulations (EPCs) in Great Tits are responsible for a difference in the resemblance of nestlings to the male and female putative parents without considering other explanations for such a difference in resemblance.…”

“…offspring heritability estimates should be higher than male-offspring estimates. Norris & Blakey (1989) recently applied this method to data for the Great Tit Parus major from two breeding seasons. In each season samples were relatively small ( 2 7 and 3 5 nests).…”

Environmental and Parental Influences on Offspring Health and Growth in Great Tits (Parus major)

“…Unfortunately, in this study we were unable to assess parentage directly using genetic techniques. It is known that extra-pair paternity occurs in great tits, estimated in a nearby population to result in 13–14% of offspring being unrelated to their social father [61]–[63]. It is therefore possible that any failure to detect relationships between offspring performance and the traits of nest-of-origin males could be due the level of extra-pair paternity.…”