Low size dimorphism does not lead to reduced sexual segregation: exploring effects of habitat divergence and activity

Abstract

While the proximate and ultimate causes of sexual segregation have been well studied over the past 30 years, most of the research has focused on species with a pronounced sexual size dimorphism. Species with a smaller size dimorphism are probably understudied, because the assumption is that aggregation rather than sex segregation should be the norm. We used 6 years of direct observations of goitered gazelles, Gazella subgutturosa , an ungulate with a small degree of sexual size dimorphism, to explore sexual segregation and aggregation patterns and habitat choice at two timescales. We predicted minimal differences in activity budgets between the sexes, based on their small size dimorphism, and did not expect any evolutionary niche divergence based on size. However, we found that goitered gazelles showed considerable sexual and habitat segregation for most of the year, and only showed a tendency to randomly aggregate during the peak of the rutting season. We also found that they segregated socially and by habitat and had different activity budgets in some months. Behavioural asynchrony and sexual differences in habitat use were much greater than predicted for a species with such a small sexual dimorphism in body size. Our study confirms strong multifactorial sexual segregation patterns, and points to the potential importance that social factors (aggression and territoriality) may have on sexual segregation in goitered gazelles. • Studies on sexual segregation mostly focus on highly sexual size-dimorphic species. • High degree of sexual segregation was found in a less size-dimorphic species. • Both habitat differentiation and activity are associated with sexual segregation. • Goitered gazelles exhibit multifactorial segregation patterns.