Chimpanzee behavioural diversity is spatially structured and negatively associated with genetic variation

Abstract

Abstract The question of how behavioural diversity in humans and other animals is shaped by the combined influence of demography, genetics, culture, and the environment receives much research attention. We take a macro-ecological approach to evaluate how chimpanzee (Pan troglodytes) behavioural diversity is spatially structured and associated with genetic diversity (i.e. heterozygosity as a proxy for effective population size) and contemporary and historic environmental context. We integrate the largest available chimpanzee behavioural and genomic datasets and apply spatially explicit Bayesian Generalised Linear Mixed Models to derive marginal effects for putative drivers and range wide spatial predictions of probability to observe behavioural traits. Contrary to expectations from neutral models of behavioural evolution, we observed a negative association of genetic diversity with behavioural diversity. This result suggests that behavioural traits may impact fitness. In contrast, we observed weaker associations of chimpanzee behavioural diversity with contemporary and historic environmental context. The very strong spatial structuring of behavioural traits is consistent with cultural transmission playing a major role in shaping chimpanzee behavioural diversity. Our analytical approach can be flexibly extended by additional candidate drivers of chimpanzee behavioural diversity, and offers a novel framework for testing competing ecological-evolutionary hypotheses across a wide variety of animal cultures.