Extra-pair Partners Research Articles

Hormonal and cycle phase predictors of within-women shifts in self-perceived attractiveness: Tests of alternative functional models

Prior research has produced mixed findings regarding whether women feel more attractive during the fertile phase of the menstrual cycle. Here, we analyzed cycle phase and hormonal predictors of women's self-perceived attractiveness (SPA) assessed within a daily diary study. Forty-three women indicated their SPA, sexual desire, and interest in their own partners or other potential mates each day across 1–2 menstrual cycles; saliva samples collected on corresponding days were assayed for estradiol, progesterone, and testosterone; and photos of the women taken at weekly intervals were rated for attractiveness. Contrary to some prior studies, we did not find a significant increase in SPA within the estimated fertile window (i.e., cycle days when conception is possible). However, within-cycle fluctuations in progesterone were significantly negatively associated with shifts in SPA, with a visible nadir in SPA in the mid-luteal phase. Women's sexual desire and SPA were positively associated, and the two variables fluctuated in very similar ways across the cycle. Third-party ratings of women's photos provided no evidence that women's SPA simply tracked actual changes in their visible attractiveness. Finally, for partnered women, changes in SPA correlated with shifts in attraction to own partners at least as strongly as it did with shifts in fantasy about extra-pair partners. Our findings provide preliminary evidence for the idea that SPA is a component of women's sexual motivation that may change in ways similar to other hormonally regulated shifts in motivational priorities. Additional large-scale studies are necessary to test replication of these preliminary findings.

The long and short of mistress relationships: Sex-differentiated mate preferences reflect a compromise of mating ideals.

Evolved mate preferences have taken center stage in evolutionary psychology research, yet this literature has been fairly muted on mate preferences for extrapair partners. Here, we examined the mate preferences for mistress relationships (the traits that men prioritize in a mistress and mistresses prioritize in their male partners) and compared these preferences to those of short- and long-term relationships. In two studies (NStudy 1a =104, NStudy 1b =191), we derived dimensions of mate preferences through exploratory factor analyses. In subsequent studies (NStudy 2 =219, NStudy 3 =101), we employed a budget allocation paradigm, where participants designed their ideal mates for different relationship types (short-term, long-term, and mistress relationships). Whereas men focused on fulfilling short-term mating ideals (by prioritizing physical attractiveness) in a mistress relationship, women focused on fulfilling long-term (but also some short-term) mating ideals (prioritizing both physical attractiveness and social status) for a mistress relationship. Findings indicate that mistress relationships reflect a compromise of men's and women's (conflicting) mating ideals and contribute to an understanding of relationships that are neither completely short- nor long-term in nature.

Understanding Extra-Pair Mating Behaviour: A Case Study of Socially Monogamous European Pied Flycatcher (Ficedula hypoleuca) in Western Siberia

Extra-pair copulation (EPC) occurred in most socially monogamous bird species. The mechanisms leading to the frequent occurrence of extra-pair offspring (EPO, EPY) in socially monogamous couples, as well as the ‘function’ of EPC, are the subjects of strong debates and raise many unanswered questions. We studied the relationship between extra-pair paternity (EPP) and the different characteristics of males and females in the European pied flycatcher in Western Siberia (Russia). The analysis was based on the genotyping of 232 males, 250 females, 1485 nestlings (250 nests). The European pied flycatchers were predominantly socially and genetically monogamous, but about 20% of birds could be involved in EPP. Loss of paternity tended to be more frequent in one-year-old males. EPCs could be multiple: one individual may have up to three extra-pair partners. The EPP rate was independent of the breeding time. The extra-pair mates of an individual were mainly its near neighbours. The EPC status of an individual was unrelated to most of its morpho-physiological traits. The occurrence of EPP was almost twice as high in females nesting in good quality territories. The fitness of within-pair offspring, EPO, paternal half-sibs of EPO and maternal half-sibs of EPO did not differ statistically significantly. Assuming very low heritability of extra-pair mating, we argued that EPCs could be incidental side effects (by-product) of selection. We believe that the evolution and maintenance of extra-pair mating are the episelective processes in the case of the European pied flycatcher.

Social network position predicts male mating success in a small passerine.

Individuals differ in the quantity and quality of their associations with conspecifics. The resulting variation in the positions that individuals occupy within their social environment can affect several aspects of life history, including reproduction. While research increasingly shows how social factors can predict dyadic mating patterns (who will breed with whom), much less is known about how an individual’s social position affects its overall likelihood to acquire mating partner(s). We studied social networks of socially monogamous blue tits (Cyanistes caeruleus) to investigate whether the number and strength of connections to opposite-sex conspecifics, the ratio between same- and opposite-sex connections, and the tendency to move between social groups in the months prior to breeding affect individuals’ success in acquiring 1) a breeding partner and 2) an extrapair partner. After controlling for differences in spatial location, we show that males that moved more often between social groups were more likely to acquire a breeding partner. Moreover, adult males that associated with more females were more likely to sire extrapair young. The number of female associates also predicted the proportion of familiar female breeding neighbors, suggesting that familiarity among neighbors may facilitate opportunities for extrapair matings. In females, none of the network metrics significantly predicted the likelihood of acquiring a breeding or extrapair partner. Our study suggests that the positioning of males within their social environment prior to breeding can translate into future mating success, adding an important new dimension to studies of (extrapair) mating behavior.

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

Many studies investigated variation in the frequency of extrapair paternity (EPP) among individuals. However, our understanding of within-individual variation in EPP remains limited. Here, we comprehensively investigate variation in EPP at the within-individual level in a population of blue tits (Cyanistes caeruleus). Our study is based on parentage data comprising >10 000 genotyped offspring across 11 breeding seasons. First, we examined the repeatability of the occurrence of EPP, the number of extrapair offspring, the number of extrapair partners, and the occurrence of paternity loss using data from males and females that bred in multiple years. Second, we tested whether within-individual changes in EPP between breeding seasons relate to between-year changes in the local social environment. Repeatabilities were generally low but significant for the occurrence and number of extrapair young in females and for whether a male sired extrapair young or not. We found no evidence that the presence of the former social partner or changes in the proportion of familiar individuals or in phenotypic traits of the neighbors influenced changes in levels of EPP in females. However, in adult males, a decrease in the average body size of male neighbors was associated with higher extrapair siring success. If confirmed, this result suggests that the competitive ability of a male relative to its neighbors influences his extrapair mating success. We suggest that alternative hypotheses, including the idea that within-individual changes in EPP are due to “chance events” rather than changes in an individual’s social breeding environment, deserve more consideration.

Extra-pair paternity patterns in European barn swallows Hirundo rustica are best explained by male and female age rather than male ornamentation

Adaptive explanations for the evolution of extra-pair paternity (EPP) in birds often assume cuckolding males to be better-ornamented than cuckolded males. Several studies have confirmed that either male sexual ornamentation is associated with EPP or that phenotypes of cuckolded and cuckolding males differ. Expression of male ornamentation may change with age; however, a recent meta-analysis has identified age itself as an important factor that differed in cuckolding and cuckolded males. The age of social female partner may also affect EPP, though this has received little attention. Here, by using detailed data on age of individual barn swallows (Hirundo rustica rustica), we identified age as the major predictor of male and female promiscuity. Our results revealed that, whereas a male’s ability to obtain an extra-pair mate increased linearly with age, the only predictor of the probability of a male being cuckolded was the age of his social partner, with older females engaging more frequently in EPP. In contrast, male ornamentation was not significantly related to EPP pattern. Tarsus length was the sole significant phenotypic trait in comparison between cuckolding and cuckolded males. Our data provide little support for the hypothesis that extra-pair mate choice in our barn swallow population was ornament driven. This may indicate either a non-adaptive scenario for EPP, for example with older males better able to coerce females into copulation, or EPP mating based on other than absolute mate-choice criteria associated with the expression of male ornamentation. SIGNIFICANCE STATEMENT: We analysed patterns of extra-pair paternity (EPP) in barn swallows. Derived from observation of 160 nests, our results appear to differ from the findings of some previous studies that identified ornamental traits as being associated with extra-pair and within-pair paternity (WPP) in this iconic model taxon of sexual selection. In particular, tail streamer length had no detectable association with WPP or a male’s ability to obtain an extra-pair partner. Pairwise comparisons of cuckolded and cuckolding males, involving 76 mixed paternity nests, also supported the hypothesis that male ornamentation does not play a role in determining EPP patterns in the focal barn swallow population. When statistically controlled for clutch initiation date, the probability of obtaining an extra-pair partner only increased with increasing age of males, while WPP was only associated with the age of their female social partners. Our data provide little support for the hypothesis that extra-pair mate choice in our barn swallow population is ornament driven and indicated that age, rather than ornaments, would be a better predictor of paternity.

Women reveal, men conceal: Current relationship disclosure when seeking an extrapair partner.

Women reveal, men conceal: Current relationship disclosure when seeking an extrapair partner.

Inclusive fitness benefits mitigate costs of cuckoldry to socially paired males

BackgroundIn socially monogamous species, reproduction is not always confined to paired males and females. Extra-pair males commonly also reproduce with paired females, which is traditionally thought to be costly to the females’ social partners. However, we suggest that when the relatedness between reproducing individuals is considered, cuckolded males can suffer lower fitness losses than otherwise expected, especially when the rate of cuckoldry is high. We combine theoretical modeling with a detailed genetic study on a socially monogamous wild fish, Variabilichromis moorii, which displays biparental care despite exceptionally high rates of extra-pair paternity.ResultsWe measured the relatedness between all parties involved in V. moorii spawning events (i.e. between males and females in social pairs, females and their extra-pair partners, and paired males and their cuckolders), and we reveal that males are on average more related to their cuckolders than expected by chance. Queller–Goodnight estimates of relatedness between males and their cuckolders are on average r = 0.038 but can range up to r = 0.64. This also increases the relatedness between males and the extra-pair offspring under their care. These intriguing results are consistent with the predictions of our mathematical model, which shows that elevated relatedness between paired males and their cuckolders can be adaptive for both parties when competition for fertilizations is strong.ConclusionsOur results show how cuckoldry by relatives can offset males’ direct fitness losses with inclusive fitness gains, which can be substantial in systems where males face almost certain paternity losses.

Extra-pair parentage and personality in a cooperatively breeding bird

Why so much variation in extra-pair parentage occurs within and among populations remains unclear. Often the fitness costs and benefits of extra-pair parentage are hypothesised to explain its occurrence; therefore, linking extra-pair parentage with traits such as personality (behavioural traits that can be heritable and affect reproductive behaviour) may help our understanding. Here, we investigate whether reproductive outcomes and success are associated with exploratory behaviour in a natural population of cooperatively breeding Seychelles warblers (Acrocephalus sechellensis) on Cousin Island. Exploratory behaviour correlates positively with traits such as risk-taking behaviour and activity in other wild bird species and might promote extra-pair mating by increasing the rate at which potential extra-pair partners are encountered. We therefore predicted that fast-exploring individuals would have more extra-pair offspring. There is also a potential trade-off between pursuing extra-pair parentage and mate guarding in males. We therefore also predicted that fast-exploring males would be more likely to pursue extra-pair parentage and that this would increase the propensity of their mate to gain extra-pair parentage. We found that neither the total number of offspring nor the number of extra-pair offspring were associated with a male’s or female’s exploratory behaviour. However, there was a small but significant propensity for females to have extra-pair fertilisations in pairs that were behaviourally disassortative. Overall, we conclude that, due to the small effect size, the association between exploratory behaviour and extra-pair paternity is unlikely to be biologically relevant.Significance statementTrue genetic monogamy is rare, even in socially monogamous systems, and multiple factors, such as behaviour, social structure, morphology and physiology, determined by the biological system can cause variation in extra-pair parentage (EPP). Therefore, investigating the inherent differences in these factors among individuals could be informative. We investigated whether reproductive outcomes/success are associated with differences in the propensity to explore novel environments/objects in a promiscuous, island-dwelling cooperatively breeding bird, the Seychelles warbler. Our results showed that exploratory behaviour was not associated with the number of offspring produced by an individual, and thus the long-term fitness consequences of different exploratory tendencies did not differ. We also found that the propensity to engage in EPP in females was higher in dissimilar behavioural pairs, but due to the small effect size, we hesitate to conclude that there are personality-dependent mating outcomes in the population.

Plumage Colouration and the Provisioning Behaviour of Male and Female Eastern Phoebes

Many factors, including nestling age, brood size, and mate quality, can influence the provisioning behaviour of adult birds. Mate quality may affect provisioning behaviour because high-quality individuals may be ‘good parents’ and provision at higher rates. Alternatively, individuals paired to high-quality mates may provision at higher rates because the benefits provided by such mates ( e.g. good genes) increase the likelihood of reproductive success. We examined variation in the plumage colour of male and female Eastern Phoebes ( Sayornis phoebe) and the possible relationship between such variation and provisioning behaviour. During the 2006–2007 breeding seasons, we captured, banded, and measured adult Eastern Phoebes and collected belly feathers for spectral analyses. We also videotaped nests to quantify provisioning behaviour. Male Eastern Phoebes were larger than females, but the plumage (belly feathers) of males and females did not differ in brightness, hue, and carotenoid chroma (all P ≥ 0.37). Females provisioned nestlings at higher rates than males ( P = 0.009), but we found no significant relationship between provisioning rates of males and females and plumage colour. However, relationships between female provisioning rates and the brightness and carotenoid chroma of their mates’ belly feathers approached significance ( P ≤ 0.08). The larger size of male Eastern Phoebes suggests there is male–male competition for access to resources ( e.g. nest sites and mates), with larger size conferring a selective advantage. However, the absence of intersexual differences in plumage colour suggests limited sexual selection driven by female choice for extra-pair partners. Differences in provisioning rates of males and females may be due to male uncertainty of paternity status or to intersexual differences in foraging behaviour. The relationship between female provisioning rates and male plumage quality suggests that females may invest more in reproduction if male Eastern Phoebes with brighter, carotenoid-rich belly plumage are better able to provide quality nest sites and territories or, perhaps, high-quality genes that can potentially enhance female fitness (differential-allocation hypothesis).

P115] Thermodynamic and kinetic investigation on the formation of periodic layered structure in Ti-Cu/Zn interface reaction

Extrapair copulations (EPCs) occur widely in socially monogamous birds. How cuckolded males respond to the infidelity of their social mates is still problematic. We addressed this question in the ground tit, Pseudopodoces humilis, in which EPCs occur frequently and successful reproduction relies on biparental care. In solitarily breeding pairs, we calculated the feeding rate of social pairs at polyandrous and monogamous females' nests. Compared with that at monogamous nests, cuckolded males increased their feeding rate whereas polyandrous females reduced theirs. Polyandrous females had larger extrapair partners, although their extrapair young were neither heavier nor had higher heterozygosity than their within-pair young. Extrapair males never provided paternal care for the mixed brood and polyandrous females had no opportunity to forage on the territory of extrapair males. Therefore, the energetic benefit polyandrous females obtained was due to the increased parental care of their social mates. Even losing some share, cuckolded males still gained most of the paternity within the mixed brood. By increasing parental care for the current brood, they could ensure the survival of their own offspring. Thus, we suggest that females place their social male in a cruel bind by creating a larger brood containing some unrelated young: if the social male does not step up provisioning to meet the demands of the larger brood, overcrowding may reduce the survival of his offspring. Polyandrous females maintain the fitness incentive for their social males to provide parental care by limiting the paternity of extrapair males to a minority of the brood.

Cuckolded male ground tits increase parental care for the brood

Extrapair copulations (EPCs) occur widely in socially monogamous birds. How cuckolded males respond to the infidelity of their social mates is still problematic. We addressed this question in the ground tit, Pseudopodoces humilis, in which EPCs occur frequently and successful reproduction relies on biparental care. In solitarily breeding pairs, we calculated the feeding rate of social pairs at polyandrous and monogamous females' nests. Compared with that at monogamous nests, cuckolded males increased their feeding rate whereas polyandrous females reduced theirs. Polyandrous females had larger extrapair partners, although their extrapair young were neither heavier nor had higher heterozygosity than their within-pair young. Extrapair males never provided paternal care for the mixed brood and polyandrous females had no opportunity to forage on the territory of extrapair males. Therefore, the energetic benefit polyandrous females obtained was due to the increased parental care of their social mates. Even losing some share, cuckolded males still gained most of the paternity within the mixed brood. By increasing parental care for the current brood, they could ensure the survival of their own offspring. Thus, we suggest that females place their social male in a cruel bind by creating a larger brood containing some unrelated young: if the social male does not step up provisioning to meet the demands of the larger brood, overcrowding may reduce the survival of his offspring. Polyandrous females maintain the fitness incentive for their social males to provide parental care by limiting the paternity of extrapair males to a minority of the brood.

A Comparison of Sexual Health History and Practices Among Monogamous and Consensually Nonmonogamous Sexual Partners

Although consensually nonmonogamous (CNM) relationships are presumed to be far riskier for partners' sexual health compared with monogamous relationships, the disparity between them may be smaller than assumed. A growing body of research finds that many partners who have made monogamy agreements cheat, and when they do, they are less likely to practice safe sex than CNM partners. Extant comparisons of monogamous and CNM relationships are rare and have yet to establish whether rates of sexually transmitted infections (STIs) and STI testing differ between these groups. The present research compared self-reported STI history, lifetime number of sex partners, and condom use practices among monogamous and CNM partners. Participants (N = 556) were recruited for an online survey of "attitudes toward sexual relationships." Approximately two-thirds of the sample reported current involvement in a monogamous relationship, with the remainder indicating involvement in a CNM relationship. All participants completed a questionnaire that included measures of condom use practices with primary and extra-pair partners, as well as their STI history. CNM partners reported more lifetime sexual partners than individuals in monogamous relationships. In addition, compared with monogamous partners, CNM partners were more likely to (i) report using condoms during intercourse with their primary partner; (ii) report using condoms during intercourse with extradyadic partners; and (iii) report having been tested for STIs. Approximately one-quarter of monogamous partners reported sex outside of their primary relationship, most of whom indicated that their primary partner did not know about their infidelity. The percentage of participants reporting previous STI diagnoses did not differ across relationship type. CNM partners reported taking more precautions than those in monogamous relationships in terms of greater condom use during intercourse with all partners and a higher likelihood of STI testing. Thus, although persons in CNM relationships had more sexual partners, the precautions they took did not appear to elevate their rate of STIs above an imperfect implementation of monogamy. Lehmiller JJ. A comparison of sexual health history and practices among monogamous and consensually nonmonogamous sexual partners.

Why inclusive fitness can make it adaptive to produce less fit extra-pair offspring.

Social monogamy predominates in avian breeding systems, but most socially monogamous species engage in promiscuous extra-pair copulations (EPCs). The reasons behind this remain debated, and recent empirical work has uncovered patterns that do not seem to fit existing hypotheses. In particular, some results seem to contradict the inbreeding avoidance hypothesis: females can prefer extra-pair partners that are more closely related to them than their social partners, and extra-pair young can have lower fitness than within-pair young. Motivated by these studies, we show that such results can become explicable when an asymmetry in inbreeding tolerance between monogamy and polygamy is extended to species that combine both strategies within a single reproductive season. Under fairly general conditions, it can be adaptive for a female to choose an unrelated social partner, but inbreed with an extra-pair partner. Inbreeding depression is compensated for by inclusive fitness benefits, which are only fully realized in EPCs. We also show that if a female has already formed a suboptimal social bond, there are scenarios where it is beneficial to engage in EPCs with less related males, and others where EPCs with more related males increase her inclusive fitness. This has implications for detecting general relatedness or fitness trends when averaged over several species.

Male extraterritorial behavior predicts extrapair paternity pattern in blue tits,Cyanistes caeruleus

In territorial species, at least 1 of the 2 individuals involved in an extrapair mating has to leave its territory in order to copulate with the extrapair partner. However, data on extraterritorial forays are difficult and time-consuming to acquire, and extensive datasets on foraying behavior are rare. Here, we use an automated recording system to investigate forays of individual blue tits (Cyanistes caeruleus) to other pair’s nest-boxes during early spring, when extrapair matings occur. The study has 3 aims. 1) To describe daily and seasonal variation in the frequency of foraying behavior. 2) To investigate which individuals perform forays. 3) To investigate whether male and female visits to other pair’s nest-boxes predict the occurrence of extrapair paternity. We find that males visited foreign nest-boxes more frequently than females, and that the majority of visits occurred in the morning hours, but not around dawn. Male visits to a foreign nest-box were unrelated to the social and the visited females’ fertile period. Male body size, but not age predicted the occurrence of forays. Males that forayed were more likely to sire extrapair offspring with the female they visited compared with nonvisiting males. Whether males copulate during such visits or whether females seek extrapair copulations from visiting males remains unknown. However, male forays to a foreign nest-box coincided with the presence of the resident female at the same nest-box more often than expected by chance. This indicates that visits to foreign nest-boxes could be an opportunity for extrapair mate assessment or extrapair copulations.

Genetic analysis of human extrapair mating: heritability, between-sex correlation, and receptor genes for vasopressin and oxytocin

As in other socially monogamous species, pair-bonded humans commonly engage in sex with a partner other than their primary mate. For men, extrapair mating is straightforwardly explained from an adaptive perspective in terms of the reproductive benefits of multiple mates. For women, whose reproductive output is limited by their reproductive biology rather than by their number of mates, the adaptive benefits of extrapair mating are less obvious. Dominant adaptive explanations focus on women obtaining genetic benefits for their offspring by mating with high-quality extrapair partners. Non-adaptive explanations have rarely been considered in humans, but recent findings in birds suggest that females' predisposition to extrapair mating may result from indirect selection, via direct selection on males and a between-sex genetic correlation. To examine the plausibility of this non-adaptive explanation of extrapair mating in women, we used data on recent extrapair mating in 7,378 Finnish twins and their siblings. Genetic modelling showed within-sex broad-sense heritability—i.e. the percentage of variation in extrapair mating due to genetic variation—of 62% in men and 40% in women. There was no between-sex correlation in extrapair mating, making indirect selection unlikely. Based on previous animal and human findings, we also tested for association of the arginine vasopressin receptor 1A gene (AVPR1A) and oxytocin receptor gene (OXTR) with extrapair mating. We found gene-based association for AVPR1A in women but not in men, and OXTR showed no significant association in either sex. Overall, these findings confirm genetic underpinnings of extrapair mating in humans, but do not suggest that women's predisposition to extrapair mating is due to selection on men.

Habitat structure and colony structure constrain extrapair paternity in a colonial bird

Individual variation in sexual fidelity and extrapair paternity (EPP) is widely attributed to environmental heterogeneity, but the only variables known to be influential are food abundance and density of conspecific breeders (potential extrapair partners). Habitat structure is thought to impact EPP but is rarely measured and, when considered, is usually confounded with food abundance and predation pressure. To sidestep these confounds, we tested whether EPP is associated with habitat structure variables and with local conspecific density in a species whose nesting habitat is not used for feeding and lacks predators. In a blue-footed booby, Sula nebouxii, colony, the probability of EPP in a female's nest was highest in parts of the study plot where there were few obstacles to locomotion, and was quadratically related to local density of sexually active males, even though local males did not sire the EP chicks. The probability of a male breeder siring EP (extrapair) chicks elsewhere was quadratically related to local density of sexually active males around his nest. From these patterns we infer that both sexes may foray for EP interactions, that males and females nesting at intermediate density are most likely to be accessed by forayers, and that obstacles in the vicinity of a female's nest constrain access of foraying males. To our knowledge, this is the first demonstration that individual variation in EPP is associated with habitat structure in the absence of confounding variation in food availability, predation pressure or breeder quality, and the first evidence that EPP opportunities of female and male breeders are reduced by high

Extra‐pair paternity in relation to breeding synchrony in ground tits: an individual‐based approach

Previous studies thought that at the within‐population level, whether a female bird engages in extra‐pair (EP) mating depends on how synchronous she is in breeding time with all other females around her, presumably the synchronization might affect the female's opportunities to meet potential EP sires who socially pair with these other females. However, when females or males are choosy about EP partners and mate with one EP individual only, the probability of EP mating may be most influenced by breeding synchrony between the EP partners. In such a case, the ‘individual‐level’ synchrony should act to determine EP mating success. We test this idea in a socially monogamous passerine, the ground tit Parus humilis. Fifty‐five out of 172 sampled females produced 122 EP offspring, each mating with one EP sire in most cases (92%), usually her intermediately‐related kin. As expected, the broader‐scale synchrony did not predict the probability of EP paternity but the individual‐level did, for females having EP offspring bred more synchronously with their EP than with their nearest neighbors, and females without EP offspring were least synchronous with their nearest neighbors. We argue that this kind of individual‐based approaches will shine light on the synchrony‐EP mating relationship in birds.

Extra-pair Paternity in Relation to Age of the Red-breasted FlycatcherFicedula Parvamales

Despite advances in knowledge, in many bird species, the true mating system is unknown, and especially so for birds breeding at low densities under natural conditions. We studied paternity at the population and breeding pair level in the Red-breasted Flycatcher ( Ficedula parva), a small, migrant passerine breeding in old-growth Białowieża Forest. Over seven breeding seasons we genotyped a total of 159 nestlings and 25 adult males as fathers from 33 broods of the Red-breasted Flycatcher. Extra-pair young were present in eight broods (24.2%). Twelve (7.5%) chicks mismatched with the ‘social’ male in several loci. Both low breeding density and synchrony in breeding phenology can explain such findings. Also of interest was the share of extra-pair paternity at the individual level, in relation to the age/ornamentation of the extra-pair male. Male Red-breasted Flycatchers exhibit delayed plumage maturation. Young males (second year) are without an orange badge on the throat and breast, while older males (after-second year) are ornamented and have an orange badge. The extra-pair nestlings were found in eight broods, four with young males as a fathers (36.4%) and four in broods of old males (18.2%). However, in all seven cases when the age of the extra-pair partner was known, irrespective of the age of the social father, the extra-pair partner was a male with an orange patch on the breast. This indicated female preference for ornamented males as partners for extra-pair copulation.

Current Hormonal Contraceptive Use Predicts Female Extra-Pair and Dyadic Sexual Behavior: Evidence Based on Czech National Survey Data

Data from 1155 Czech women (493 using oral contraception, 662 non-users), obtained from the Czech National Survey of Sexual Behavior, were used to investigate evolutionary-based hypotheses concerning the predictive value of current oral contraceptive (OC) use on extra-pair and dyadic (in-pair) sexual behavior of coupled women. Specifically, the aim was to determine whether current OC use was associated with lower extra-pair and higher in-pair sexual interest and behavior, because OC use suppresses cyclical shifts in mating psychology that occur in normally cycling women. Zero-inflated Poisson (ZIP) regression and negative binomial models were used to test associations between OC use and these sexual measures, controlling for other relevant predictors (e.g., age, parity, in-pair sexual satisfaction, relationship length). The overall incidence of having had an extra-pair partner or one-night stand in the previous year was not related to current OC use (the majority of the sample had not). However, among the women who had engaged in extra-pair sexual behavior, OC users had fewer one-night stands than non-users, and tended to have fewer partners, than non-users. OC users also had more frequent dyadic intercourse than non-users, potentially indicating higher commitment to their current relationship. These results suggest that suppression of fertility through OC use may alter important aspects of female sexual behavior, with potential implications for relationship functioning and stability.