Latitudinal gradient and species traits determine bat distributions across Europe

Climatic and anthropogenic impacts have determined the extinction of species in the past and are also the main factors shaping their present distribution ranges. Geographic range size – a biogeographic variable commonly used to assess population abundance, survival, and conservation status – varies with latitude. According to Rapoport’s rule, range size typically increases with latitude in mammals. Bats differ from other groups of mammals with regards to numerous morphological, physiological, and behavioral adaptations of sensory and motor systems. Nevertheless, bats are a suitable group for evaluating the rule because they show a strong latitudinal gradient in species richness. Our aim was to investigate the distribution patterns of European bat fauna based on two biogeographic variables 1) geographical range size and 2) average latitude of their distribution range, and investigate whether species traits characteristic to bats, mobility and hibernation, are associated with variation in range size and latitudinal distribution. We collected geographical data and species trait data on 44 European bat species from the literature. We discovered that range size and average latitude of distribution range follows Rapoport’s rule to a high degree in bats. Additionally, traits related to hibernation and movement behavior, more specifically hibernation breadth (indicating how widely a species utilizes different types of hibernacula) and mobility (based on seasonal movements), are associated with large distribution ranges and could affect northerly ranges in European bats. Range size does not only assist in directing conservation of threatened species, but it also provides insights into fundamental processes such as dispersal and adaptation. Our results emphasize that knowledge on the relationship between traits and species distribution is important for understanding current distribution patterns and could work as background information for predictive models on the effect of future landscape changes.