Sex-Biased Dispersal and Social Systems of Neotropical Emballonurids

Abstract

The most common pattern of sex-biased dispersal in mammals including temperate bats is that females remain philopatric and males disperse from their natal groups. In contrast, sex-biased dispersal patterns in tropical bat species appear much more variable, ranging from all-offspring dispersal to female-biased dispersal and male-biased dispersal. The identity of the philopatric sex is essential for the kin structure of social groups (i.e. matrilineal relatives in species with female philopatry and patrilineal relatives in species with male philopatry) and thus for the evolution of social behavior. This book chapter contrasts sex-biased dispersal and the social systems of three well-studied Neotropical bat species of the family Emballonuridae. Two of these Neotropical Emballonurids exhibit exceptional female-biased dispersal and male philopatry in combination with resource-defense polygyny (greater sac-winged bat Saccopteryx bilineata) or female-defense polygyny (proboscis bat Rhynchonycteris naso). However, in the gray sac-winged bat (Balantiopteryx plicata) females are the more philopatric sex and the social system involves some sort of sexual segregation with mating probably taking place at male mating aggregations. To conclude, we discuss the evolutionary pressures driving the observed dispersal patterns and how sexual selection in Neotropical Emballonurids with male philopatry might shape bat sociality.