Comparing social dynamics and telomere attrition between high promiscuity and low promiscuity flocks of zebra finches (Taeniopygia guttata)

Abstract

Extra-pair paternity (EPP) is now recognised as a widespread phenomenon among socially monogamous avian systems, but the factors driving intraspecific variation in extra-pair mating behaviours are still poorly understood. Here, I quantified EPP in two promiscuity breeding lines of the zebra finch (Taeniopygia guttata), which had been selected to have high or low breeding values of male sex drive. I found that the majority of birds were involved in extra-pair mating behaviour, and the prevalence of EPP did not differ between the two breeding lines. I present evidence that males can benefit from an increased reproductive output by engaging in extra-pair mating strategies. However, I found no evidence that males reproduced with a larger number of different mates as compared to the females in the population. I also tested the hypothesis that extra-pair mating behaviour could be stressful due to its potential to compromise social pair bonds. To do so, I conducted a within-individual repeated-measures study of telomere attrition across an experimentally-controlled breeding season. Telomere dynamics have become widely regarded as a long-term indicator of cumulative stress and biological age. I found no conclusive evidence that receiving infidelity or experiencing weaker pair bonds induces sufficient physiological stress in zebra finches for it to affect telomere dynamics. I present evidence that in this species, some individuals experienced telomere lengthening while others experienced shortening, with the longest telomeres shortening the fastest. I demonstrate that individuals with stronger social associations produced more eggs together, both within and outside the social pairs (i.e. through EPP). For this reason, I suggest that future research investigating extra-pair mating behaviours should consider the role that the social environment plays in extra-pair reproduction. This could help us gain a further understanding of how social associations influence extra-pair mate selection and the prevalence of EPP within socially monogamous species.