Variation in grouping patterns, mating systems and social structure: what socio-ecological models attempt to explain

Abstract

Socio-ecological models aim to predict the variation in social systems based on a limited number of ecological parameters. Since the 1960s, the original model has taken two paths: one relating to grouping patterns and mating systems and one relating to grouping patterns and female social structure. Here, we review the basic ideas specifically with regard to non-human primates, present new results and point to open questions. While most primates live in permanent groups and exhibit female defence polygyny, recent studies indicate more flexibility with cooperative male resource defence occurring repeatedly in all radiations. In contrast to other animals, the potential link between ecology and these mating systems remains, however, largely unexplored. The model of the ecology of female social structure has often been deemed successful, but has recently been criticized. We show that the predicted association of agonistic rates and despotism (directional consistency of relationships) was not supported in a comparative test. The overall variation in despotism is probably due to phylogenetic grade shifts. At the same time, it varies within clades more or less in the direction predicted by the model. This suggests that the model's utility may lie in predicting social variation within but not across clades.

Male tolerance and male–male bonds in a multilevel primate society

“…Attempts to explain primate social evolution therefore must take phylogenetic relationships into consideration (42). It is becoming increasingly clear that the diversity in social organization among populations may arise not only from past or current selection pressures but also from the dynamics and stochasticity of spatial processes during range expansion.…”

Constraints and flexibility in mammalian social behaviour: introduction and synthesis

“…Ecological factors also explain variation in marmot social organization [142]. The above-mentioned socioecological model provides the starting point of a comparative analysis by Koenig et al [143] in which they test predictions about links between ecology and mating systems among primates, scrutinizing the predictive power of socioecological models and demonstrating the necessity of testing and refining existing theoretical frameworks in social evolution. Ecological factors can also exert strong influences on intraspecific variation in social systems.…”

“…As shown by Schradin [130] (see [144]), flexibility evolves especially in unpredictable environments with repeated similar changes, or in marginal habitats [145], selecting for genotypes that enable a broad reaction norm for social behaviour. A broad consensus appears to be emerging among behavioural ecologists, however, that ecological constraints on behavioural flexibility should no longer be studied in isolation of other factors [135,143].…”

Social Interactions and Proximal Spacing in Woolly Monkeys: Lonely Females Looking for Male Friends

“…Although some aspects of the sociological models have been supported with empirical data, recent studies have also shown that some of the assumptions are not correct and other points are difficult or impossible to test (Clutton-Brock and Janson 2012). Therefore, the study of the potential effects of ecological factors on the social structure of primate groups is still a matter of debate, where cooperation, including the role of males and phylogenetic signals, also seems to play an important role (Koenig et al 2013;Thierry 2013).…”