Gyarmathy Helga, Kopena Renáta, Kneifel Tünde, Sarkadi Fanni, Szöllősi Eszter, Szász Eszter, Török János, Rosivall Balázs
Behavioural Ecology Group, Department of Systematic Zoology and Ecology ELTE Eötvös Loránd University Budapest Hungary.
Doctoral School of Biology, Institute of Biology ELTE Eötvös Loránd University, Institute of Biology Budapest Hungary.
Ecol Evol. 2025 May 7;15(5):e71423. doi: 10.1002/ece3.71423. eCollection 2025 May.
Extra-pair paternity (EPP) is a widespread phenomenon, as EPP has been observed in 76% of the socially monogamous bird species. Many hypotheses try to explain the evolution of infidelity. While females may participate in extra-pair copulations, for instance, to ensure the fertilisation of their eggs or to obtain potential genetic benefits for their offspring, unfaithful females face many potential costs too. As nestling provisioning is one of, if not the most energetically costly forms of parental care, the certainty of paternity hypothesis predicts that males with an unfaithful partner reduce their parental investment to avoid the fitness loss arising from rearing unrelated nestlings. We investigated the relationship between the presence and proportion of extra-pair young (EPY) and the feeding rate of the social male to reveal whether males recognise and penalise unfaithfulness. We conducted the study in a Hungarian population of collared flycatchers () where the EPP rate had been reported to be high. We cross-fostered nestlings so that each parent reared offspring from two foreign broods and none from their own. Thus, any relationship between paternal investment and paternity in the original brood of the male should be the direct consequence of the female's mating behaviour (as perceived by the male) and not the result of early maternal effects or different behaviour of extra- and within-pair offspring. We found that 63.6% of the broods contained EPY, and 23% of the nestlings were sired by extra-pair fathers. The only relationship we found was that males with larger broods fed their offspring more frequently. Neither the prevalence nor the proportion of EPY was related to the male feeding rate; thus, our results do not support the certainty of paternity hypothesis. This might be explained by the inability of the males to track their females' behaviour in a population with a high EPP rate.
配偶外交配（EPP）是一种普遍存在的现象，因为在76%的社会性一夫一妻制鸟类物种中都观察到了配偶外交配。许多假说试图解释不忠行为的进化。例如，雌性可能参与配偶外交配，以确保其卵子受精或为其后代获得潜在的遗传益处，但不忠的雌性也面临许多潜在成本。由于雏鸟喂养是亲代抚育中能量消耗最大的形式之一（即便不是最大的），父权确定性假说预测，配偶不忠的雄性会减少其亲代投资，以避免因养育无血缘关系的雏鸟而导致的适应性损失。我们研究了配偶外雏鸟（EPY）的存在和比例与社会性雄性的喂养率之间的关系，以揭示雄性是否能识别并惩罚不忠行为。我们在匈牙利的白领姬鹟种群中进行了这项研究，该种群的配偶外交配率据报道很高。我们对雏鸟进行了交叉寄养，以便每个亲代养育来自两个外来巢穴的后代，而不养育自己巢穴的后代。因此，雄性在其原巢穴中亲代投资与父权之间的任何关系都应该是雌性交配行为（如雄性所感知的）的直接结果，而不是早期母性效应或配偶外与配偶内后代不同行为的结果。我们发现，63.6%的巢穴中有配偶外雏鸟，23%的雏鸟是由配偶外的父亲所生。我们发现的唯一关系是，巢穴较大的雄性更频繁地喂养其后代。配偶外雏鸟的发生率和比例均与雄性喂养率无关；因此，我们的结果不支持父权确定性假说。这可能是因为在配偶外交配率高的种群中，雄性无法追踪其雌性的行为。
