Social Familiarity and Spatially Variable Environments Independently Determine Reproductive Fitness in a Wild Bird.

AbstractThe social interactions that an individual experiences are a key component of its environment and can have important consequences for reproductive success. The dear enemy effect posits that having familiar neighbors at a territory boundary can reduce the need for territory defense and competition and potentially increase cooperation. Although fitness benefits of reproducing among familiar individuals are documented in many species, it remains unclear to what extent these relationships are driven by direct benefits of familiarity itself versus other socioecological covariates of familiarity. We use 58 years of great tit (Parus major) breeding data to disentangle the relationship between neighbor familiarity, partner familiarity, and reproductive success while simultaneously considering individual and spatiotemporal effects. We find that neighbor familiarity was positively associated with reproductive success for females but not males, while an individual's familiarity with their breeding partner was associated with fitness benefits for both sexes. There was strong spatial heterogeneity in all investigated fitness components, but our findings were robust and significant over and above these effects. Our analyses are consistent with direct effects of familiarity on individuals' fitness outcomes. These results suggest that social familiarity can yield direct fitness benefits, potentially driving the maintenance of long-term bonds and evolution of stable social systems.

Recognising the key role of individual recognition in social networks.

Many aspects of sociality rely on individuals recognising one another. Understanding how, when, and if individuals recognise others can yield insights into the foundations of social relationships and behaviours. Through synthesising individual recognition research in different sensory and social domains, and doing so across various related social contexts, we propose that a social network perspective can help to uncover how individual recognition may vary across different settings, species, and populations. Specifically, combining individual recognition with social networks has unrecognised potential for determining the level and relative importance of individual recognition complexity. This will provide insights not only on the ecology and evolution of individual recognition itself, but also on social structure, social transmission, and social interactions such as cooperation.

Exploring the causes and consequences of cooperative behaviour in wild animal populations using a social network approach.

Understanding why individuals carry out behaviours that benefit others, especially genetically unrelated others, has been a major undertaking in many fields and particularly in biology. Here, we focus on the cooperation literature from natural populations and present the benefits of a social network approach in terms of how it can help to identify and understand factors that influence the maintenance and spread of cooperation, but are not easily captured when solely considering independent dyadic interactions. We describe how various routes to cooperation can be tested within the social network framework. Applying the social network approach to data from natural populations can help to uncover the evolutionary and ecological pressures that lead to differences in cooperation and other social processes.