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In animal societies, individuals can cooperate in a variety of tasks, including rearing young. Such cooperation is observed in complex social systems, including communal and cooperative breeding. In mammals, both these social systems are characterized by delayed dispersal and alloparenting, whereas only cooperative breeding involves reproductive suppression. While the evolution of communal breeding has been linked to direct fitness benefits of alloparenting, the direct fitness cost of reproductive suppression has led to the hypothesis that the evolution of cooperative breeding is driven by indirect fitness benefits accrued through raising the offspring of related individuals. To decipher between the evolutionary scenarios leading to communal and cooperative breeding in carnivores, we investigated the coevolution among delayed dispersal, reproductive suppression, and alloparenting. We reconstructed ancestral states and transition rates between these traits. We found that cooperative breeding and communal breeding evolved along separate pathways, with delayed dispersal as the first step for both. The three traits coevolved, enhancing and stabilizing one another, which resulted in cooperative social systems as opposed to intermediate configurations being stable. These findings promote the key role of coevolution among traits to stabilize cooperative social systems and highlight the specificities of evolutionary patterns of sociality in carnivores. [ABSTRACT FROM AUTHOR]

Three main hypotheses have been proposed to explain mate switching in monogamous species: the “better option” hypothesis, the incompatibility hypothesis, and the “forced divorce” hypothesis. We tested the predictions of these hypotheses for the first time in a monogamous mammal using long-term data from a natural population of Alpine marmots (Marmota marmota). Generally, pair disruption resulted in one of the pair members staying on the territory and re-pairing with a younger incomer, whereas the other disappeared from the territory. Replaced individuals were rarely found as dominant in a territory but were often injured or found dead. Individuals gained no benefit from mate switching: new mates were neither heavier, larger, or more heterozygote nor more genetically compatible than previous mates. Moreover, no increase in reproductive success was observed after re-pairing. The relationship between reproductive failure and occurrence of mate change was mainly due to infanticide by the incomer. Our results support the “forced divorce” hypothesis in the Alpine marmot and suggest that mate switching has strong consequences on breeding success. We discuss the importance of taking into account the cases of forced divorce while studying mate switching process and its evolutionary consequences in monogamous species. [ABSTRACT FROM PUBLISHER]

The article provides information on a study that examined the impact of the social structure and of the type of pair bonding on the interspecific variations of extra-pair paternity rates, using the genetic estimates of paternity available for 22 species of socially monogamous mammals. It discusses the material and methods used in the study. The research found that no interaction happened between the effects of the strength of pair bonding and social structure. Based on the study, the ability of males to monopolize breeding females is an important determinant of extra-pair paternity.