Partner’s age, not social environment, predicts extrapair paternity in wild great tits (Parus major)

Abstract

An individual’s fitness is not only influenced by its own phenotype, but by the phenotypes of interacting conspecifics. This is likely to be particularly true when considering fitness gains and losses caused by extrapair matings, as they depend directly on the social environment. While previous work has explored effects of dyadic interactions, limited understanding exists regarding how group-level characteristics of the social environment affect extrapair paternity (EPP) and cuckoldry. We use a wild population of great tits (Parus major) to examine how, in addition to the phenotypes of focal parents, two neighborhood-level traits—age and personality composition—predict EPP and cuckoldry. We used the well-studied trait “exploration behavior” as a measure of the reactive-proactive personality axis. Because breeding pairs inhabit a continuous “social landscape,” we first established an ecologically relevant definition of a breeding “neighborhood” through genotyping parents and nestlings in a 51-ha patch of woodland and assessing the spatial predictors of EPP events. Using the observed decline in likelihood of EPP with increasing spatial separation between nests, we determined the relevant neighborhood boundaries, and thus the group phenotypic composition of an individual’s neighborhood, by calculating the point at which the likelihood of EPP became negligible. We found no evidence that “social environment” effects (i.e., neighborhood age or personality composition) influenced EPP or cuckoldry. We did, however, find that a female’s own age influenced the EPP of her social mate, with males paired to older females gaining more EPP, even when controlling for the social environment. These findings suggest that partner characteristics, rather than group phenotypic composition, influence mating activity patterns at the individual level.

Sexual selection and personality: Individual and group‐level effects on mating behaviour in red junglefowl

“…Several previous studies have demonstrated links between male personality and male mating strategies (Patrick et al, 2011;Reaney & Backwell, 2007) and/or female preferences (Dzieweczynski et al, 2013;Godin & Dugatkin, 1996;Reaney & Backwell, 2007;Schuett et al, 2011;Teyssier et al, 2014). For example, in one pop- Araya-Ajoy et al, 2016;Roth et al, 2019). Similarly, bolder male fiddler crabs have been shown to court females more than shyer males, winning female preference and obtaining more mates (Reaney & Backwell, 2007).…”

“…boldness, disassortative mating, exploration, group phenotypic composition, negative frequency dependence, social selection often pairs mate. In a population of socially monogamous great tits Parus major, males that were, on average, more aggressive and explorative gained a lower share of extra-pair paternity (Araya-Ajoy et al, 2016; but see Patrick et al, 2011;Roth et al 2019). In the more promiscuous field cricket Gryllus bimaculatus, on the other hand, consistently more aggressive males may be favoured in postcopulatory sexual selection (Tuni et al, 2018).…”

Analysis of within-individual variation in extrapair paternity in blue tits (Cyanistes caeruleus) shows low repeatability and little effect of changes in neighborhood

“…In females, variation in the competitiveness of the breeding neighborhood did not explain between-year changes in EPP ( Table 5 ). Similarly, in great tits, the phenotypic composition of the neighborhood (in this case, age and exploration behavior of both sexes) was not related to patterns of EPP within years ( Roth et al 2019 ). Although familiarity among neighbors could potentially also enhance the probability of extrapair copulations, we found no evidence for such effects.…”

“…For example, in blue tits, adult (compared to yearling) and larger males are more successful in siring extrapair young ( Kempenaers et al 1997 ; Schlicht et al 2015a ). Because most extrapair young are sired by first- or second-order neighbors ( Schlicht et al 2015a ), the number or proportion of large, adult male neighbors may influence the likelihood that a pair has extrapair young in their nest or for a focal male to sire extrapair young in a neighboring nest (but see Roth et al 2019 ). Similarly, there is competition among females ( Kempenaers 1994 ; Midamegbe et al 2011 ).…”

Assessing age, breeding stage, and mating activity as drivers of variation in the reproductive microbiome of female tree swallows

“…Further, while our study assessed the number of mates per female using the number of sires per brood as a proxy, we did not consider the number of mates of the socially partnered male. In great tits ( Parus major ), males socially paired to older females secured higher rates of extra‐pair paternity (Roth et al., 2019 ), potentially transmitting bacteria acquired from those extra‐pair copulations back to their social partners. There is also a positive relationship between male age and extra‐pair paternity, as evidenced in two meta‐analyses incorporating studies done across passerine species (Cleasby & Nakagawa, 2012 ; Hsu et al., 2015 ).…”