Nest desertion is not predicted by cuckoldry in the Eurasian penduline tit

Engagement in extra-pair copulations is an example of the abundant conflicting interests between males and females over reproduction. Potential benefits for females and the risk of cuckoldry for males are expected to have important implications on the evolution of parental care. However, whether parents adjust parental care in response to parentage remains unclear. In Eurasian penduline tits Remiz pendulinus, which are small polygamous songbirds, parental care is carried out either by the male or by the female. In addition, one third of clutches is deserted by both male and female. Desertion takes place during the egg-laying phase. Using genotypes of nine microsatellite loci of 443 offspring and 211 adults, we test whether extra-pair paternity predicts parental care. We expect males to be more likely to desert cuckolded broods, whereas we expect females, if they obtain benefits from having multiple sires, to be more likely to care for broods with multiple paternity. Our results suggest that parental care is not adjusted to parentage on an ecological timescale. Furthermore, we found that male attractiveness does not predict cuckoldry, and we found no evidence for indirect benefits for females (i.e., increased growth rates or heterozygosity of extra-pair offspring). We argue that male Eurasian penduline tits may not be able to assess the risk of cuckoldry; thus, a direct association with parental care is unlikely to evolve. However, timing of desertion (i.e., when to desert during the egg-laying phase) may be influenced by the risk of cuckoldry. Future work applying extensive gene sequencing and quantitative genetics is likely to further our understanding of how selection may influence the association between parentage and parental care

Parental care and mating behaviour of polyandrous dunnocks Prunella modularis related to paternity by DNA fingerprinting

INDIVIDUALS are often assumed to behave so as to maximize their reproductive success1 but unambiguous determination of parentage is difficult, especially in species with complex social systems where a female may mate with several males and where there may also be intraspecific brood parasitism2,4. Even in apparently monogamous species, extra-pair paternity can be common5,7. DNA fingerprinting8,11 promises to revolutionize field studies by providing a powerful method for determining paternity and maternity12. Here we use this technique to link observations of mating behaviour and parental care with precise measurements of reproductive success. We show that in the dunnock Prunella modularis, a small passerine bird with a variable mating system13,14, males do not discriminate between their own young and those of another male in multiply-sired broods. Nevertheless, they increase their own reproductive success by feeding offspring in relation to their access to the female during the mating period, which is a good predictor of paternity