High level of extra-pair paternity in the socially monogamous Marsh Tits (Poecile palustris)

Background Extra-pair copulation behavior has been widely studied among socially monogamous birds. Many species revealed high rates of extra-pair paternity. But few of the studies have been carried out in the Asian population. Methods From 2012 to 2019, we explored the extra-pair paternity of Marsh Tits (Poecile palustris) in Xianrendong National Nature Reserve, Liaoning Province, China. During the study, adult Marsh Tits were captured with mist nets and parental birds, with nest-box traps. Blood samples were taken from the brachial vein. Parentage analyses were carried out using nine highly variable microsatellite loci through Cervus 3.0 software and maximum likelihood approach. Results Forty-nine offspring (15.08%) from 20 nests (45.45%) were the results of extra-pair fertilization out of a total of 325 offspring in 44 nests. The average extra-pair offspring ratio was 33.54%, with a set varying from 11.11 to 71.43%. Nine extra-pair fathers had been successfully identified, four of whom were the close neighbors of the focus nest while the nests of the remaining five were relatively far. No significant difference was found in the genetic similarity between the social and extra-pair mates of the female, nor in the heterozygosis among the maternal half-siblings. Conclusions In general, our study proved that the extra-pair paternity in Marsh Tits and its extra-pair mating is independent of the genetic compatibility hypothesis. This complements the understudied bird’s extra-pair paternity in Asian area and contributes to the comprehensive insight of birds’ extra-pair paternity behaviors.

Body size is associated with yearling breeding and extra-pair mating in the Island Scrub-Jay

Large body size is an important determinant of individual fitness in many animal species, especially in island systems where habitat saturation may result in strong intraspecific competition for mates and breeding territories. Here we show that large body size is associated with benefits to yearling breeding and extra-pair mating in the Island Scrub-Jay (Aphelocoma insularis), endemic to Santa Cruz Island, California. This species is ~20% larger than its mainland congener, consistent with the island syndrome, indicating that body size may be a trait under selection. From 2009 to 2013, we quantified the reproductive success of a marked population of Island Scrub-Jays, tracked which yearlings acquired a breeding territory and bred, and measured the occurrence of extra-pair paternity. Two potential contributors to fitness were positively related to body size. Larger yearling males were more likely to breed, possibly due to greater behavioral dominance during aggressive encounters. Larger males were also less likely to lose paternity to extra-pair males and, anecdotally, extra-pair males were larger than the social male cuckolded. This study provides evidence that larger males may have a fitness advantage over smaller males by breeding earlier and avoiding paternity loss, but estimates of lifetime reproductive success are ultimately needed for Island Scrub-Jays and other long-lived species.

An integrative measure of cognitive performance, but not individual task performance, is linked to male reproductive output in budgerigars

Cognitive abilities such as learning and memory are key for survival and reproduction. Individuals with high cognitive abilities may be more successful at attracting mates and producing offspring. However, empirical tests of and evidence supporting this hypothesis remain scarce. We measured cognitive performance of male budgerigars in four tasks: problem solving, detour reaching, seed discrimination, and spatial memory. We then tested female choice for male cognition at three stages of the mating choice process: social pairing, extra-pair mating, and continued reproductive investment with a social mate. We also measured female reproductive output. We used an integrative measure of male cognitive performance that encapsulates performance across all tasks, the ‘composite cognitive score’ by summing performance on the four tasks. In the first stage, females did not choose their social mates based on any of the measures of male cognitive performance. In the second stage, however, males with higher composite cognitive scores sired and raised more offspring. In the third stage, females increased their reproductive investment after the first breeding attempt when paired with males with higher detour-reaching scores. These results suggest that female reproductive decisions may shape overall male cognitive performance.

It's not what it looks like!

The notion of extra pair mating interests is seen as controversial in Western societies where monogamy is the dominant mating system. Attending to attractive others is often seen as an indicator of, or antecedent to engaging in infidelity. However, we argue that attending to attractive others is an adaptive and automatic process because it informs and maintains plasticity in mating strategies. Previous research has examined later attentional processes in relation to potential mates, but not early attentional capture which is beyond conscious control. Participants indicated whether they were predominantly attracted to male or female faces, then completed two flicker tasks, each consisting of faces of the gender the participants indicated they were most attracted to; one consisted of a grid of attractive faces and the other consisted of unattractive faces. Time taken to detect changes to the attractive or unattractive faces was measured as an indication of attentional bias towards potential mates. Sociosexual desires and self reported romantic interests outside of the primary relationship predicted a quicker response time to attractive faces relative to unattractive faces. Relationship status, sex of the participant, sociosexual attitudes, sociosexual behaviours, and self reported sexual interests outside of the primary relationship did not predict response time on the flicker tasks. The results suggest early attentional processes are biased towards potential mates in a given environment which calibrates and maintains plasticity in mating strategies, however this does not necessarily indicate an inclination towards infidelity.

Heritability of the extra-pair mating behaviour of the pied flycatcher in Western Siberia

Males and females take part in extra-pair copulations in most socially monogamous bird species. The mechanisms leading to the frequent occurrence of extra-pair offspring in socially monogamous couples are strongly debated and unresolved, and they are often difficult to distinguish from one another. Most hypotheses explaining the evolution of extra-pair reproduction suggest selective and adaptive scenarios for their origination and persistence. Is extra-pair paternity a heritable trait? We evaluated the heritability of extra-pair paternity in the pied flycatcher (Ficedula hypoleuca) nesting in Western Siberia. Estimated heritability was low: depending on the model used, the point estimate of the heritability (mode) varied from 0.005 to 0.11, and the bounds of the 95% confidence interval are [0–0.16] in the widest range. Thus, it seems that extra-pair mating behaviour in the pied flycatchers is a plastic phenotypic mating tactic with a small or no genetic component. Our data can help to understand the evolution of extra-pair mating behaviour in socially monogamous species.

Female and male plumage colour is linked to parental quality, pairing and extra-pair mating in a tropical passerine

ABSTRACTSexual selection has been proposed to drive the evolution of elaborate phenotypic traits in males, which often confer success in competition or mating. However, in many species both males and females display such traits, although studies reporting selection acting in both sexes are scarce. In this study, we investigated whether plumage ornamentation is sexually selected in female and male lovely fairy-wrens Malurus amabilis, a cooperatively breeding songbird. We found that female and male plumage colour was correlated with parental quality but did not incur survival costs. We also found evidence of positive assortative mating based on plumage colour. Microsatellite analyses of paternity indicated that the lovely fairywren has high levels of extra-pair paternity, with 53% of offspring resulting from extra-pair mating. Female and male plumage colour did not predict reproductive success and female proportion of extra-pair offspring in its own nest, but less colourful males obtained higher extra-pair paternity. We argue that plumage colour may be under sex-specific selection, highlighting the importance of looking at both sexes in studies of sexual selection and ornament evolution. The current findings together with previous study, suggest that plumage colour in female and male lovely fairy-wrens appears to be an honest signal relevant in both intra and inter-sexual competition contexts.

Winter associations predict social and extra-pair mating patterns in a wild songbird

Despite decades of research, our understanding of the underlying causes of within-population variation in patterns of extra-pair paternity (EPP) remains limited. Previous studies have shown that extra-pair mating decisions are linked to both individual traits and ecological factors. Here, we examine whether social associations among individuals prior to breeding also shape mating patterns, specifically the occurrence of EPP, in a small songbird, the blue tit. We test whether associations during the non-breeding period predict (1) future social pairs, (2) breeding proximity (i.e. the distance between breeding individuals) and (3) the likelihood that individuals have extra-pair young together. Individuals that were more strongly associated (those that foraged more often together) during winter tended to nest closer together. This, by itself, predicts EPP patterns, because most extra-pair sires are close neighbours. However, even after controlling for spatial effects, female–male dyads with stronger social associations prior to breeding were more likely to have extra-pair young. Our findings reveal a carry-over from social associations into future mating decisions. Quantifying the long-term social environment of individuals and studying its dynamics is a promising approach to enhance our understanding of the process of (extra-)pair formation.

Multiple and Extra-Pair Mating in a Pair-Living Hermaphrodite, the Intertidal Limpet Siphonaria gigas

Synopsis Pair-living is a common social system found across animal taxa, and the relationship between pair-living and reproduction varies greatly among species. Siphonaria gigas, hermaphroditic pulmonate gastropods, often live in pairs in the rocky intertidal zone of the tropical Eastern Pacific. Combining genetic parentage analysis using four polymorphic microsatellite loci with behavioral observations from a 10-week field study, we provide the first description of the mating system of a Siphonaria species incorporating genetic data. S. gigas mated both within-pair and extra-pair and three out of four paired S. gigas individuals produced egg masses with extra-pair paternity. Multiple paternity was detected, but at a relatively low frequency (19% of egg masses) compared to other marine gastropods. Behavioral data indicate one potential advantage of pair-living: paired S. gigas produced almost twice as many egg masses as their solitary counterparts over four reproductive cycles. These observations, together with constraints on the movement of S. gigas, suggest that pairing may ensure mate access and increase reproductive success.

Does experimentally altered plumage brightness influence extra-pair mating success in female Tree Swallows (Tachycineta bicolor)?

Recent empirical evidence suggests that ornamental traits displayed by female birds may reflect aspects of their quality, and function during competitive interactions and (or) social mate attraction; however, less is known about how such traits influence extra-pair paternity. In Tree Swallows (Tachycineta bicolor (Vieillot, 1808)), plumage brightness of females signals their quality and may be related to extra-pair paternity if it enables them to invade the territories of other females to seek extra-pair copulations and (or) if potential extra-pair mates perceive their plumage brightness as attractive. Therefore, to examine whether the plumage brightness displayed by females influence rates of extra-pair paternity and the number of sires per brood, we experimentally enhanced and reduced the plumage brightness of females relative to controls. Our results showed that plumage brightness treatment of the female did not influence the number of extra-pair offspring in nests or the likelihood of a brood containing extra-pair offspring. Additionally, the number of extra-pair males siring offspring within the broods of females did not differ by plumage brightness treatment. Although extra-pair paternity has been shown to be beneficial for female Tree Swallows, our results suggest that plumage brightness of females does not influence their ability to engage in extra-pair mating.