My cave, my rules: specialization, modularity, and topology of bat-fly interactions in hot and cold caves from eastern South America

Abstract

Caves provide relatively stable and advantageous roosting sites for bats compared to more open roosts, like tree foliage. This environment may have the drawback of facilitating interactions with their ectoparasites due to the confined spaces. Understanding the structure of interactions between bats, acting as hosts, and bat flies, serving as parasites in cave ecosystems, is a crucial first step in deciphering the roles of each species (pullers and pushers) within the networks that form in subterranean ecosystems. Here, we describe and evaluate the network structures of bat-fly interactions in two distinct cave systems: cold caves (n = 10), also known as bat caves, and hot caves (n = 6). Based on the records of 700 bats from 16 species and 1.412 bat flies from 30 species we uncovered highly distinct topologies comparing hot and cold bat caves that differed also in terms of interactions, specializations, and modularity. We found relatively lower specialization and modularity in hot caves compared to the cold caves, which may be associated to the bat composition and the cave microclimate. Bat flies were highly species-specific in relation to their bat hosts and dependent on the bats in both hot and cold caves systems. The differences in network structure and at the species level between the bat (cold) and hot caves systems suggest that bat-fly interactions are shaped by the host species' composition and by the cave system type. Those differences stem from each bat species' adaptation to extreme cave microclimates and their species-specific roosting behaviors.