Doctor of Philosophy (PhD)


Biological Sciences

Document Type



Although group living has been associated with high fitness cost, multiple lines of evidence have suggested that it has evolved multiple times independently. Given the wide diversity of social systems, it appears that multiple explanations are necessary to understand this process. Although evidence indicates that multiple ecological and environmental factors might promote variation in cohesion of social organisms, studies investigating how these factors interrelate and shape social structure have been limited. In the tropics, there are at least 23 bat species that roost in modified structures called tents. These species present a wide diversity in social systems. Moreover, they have divergent evolutionary origins but similar roosting habits, suggesting convergence in roost use. These characteristics make this group an ideal system to test hypotheses regarding effects of ecological and environmental factors in evolution and stability of social groups. Thus, my objectives were first to investigate the importance of habitat factors in predicting presence and density of the tent-roosting bat Uroderma bilobatum. Additionally, I wanted to determine relative contributions of habitat factors on group cohesion and stability. I found that presence of coconut palms (Cocos nucifera) had the highest unique predictive power of presence and density of U. bilobatum. Additionally, I found that roost characteristics contributed more to the explained variation in group relatedness. This pattern was driven by relatedness of adult females within social groups, suggesting that females using roosts of specific characteristics exhibit higher relatedness. To determine if this pattern holds across multiple tent-roosting bat species, I tested for correlated evolution between group stability and roost lifespan. I found that most bats that used tents of short lifespan also had stable groups, and most species that used tents of long lifespan had unstable groups, suggesting that group stability and tent lifespan did not evolve independently. The observed relationships between roosting ecology, group cohesion and stability in tent-roosting bats suggest that roosts play an important role in the evolution of group formation. Incorporating ecological and environmental factors in the study of sociality will allow broad understanding of the forces that bring together individuals into cohesive social groups.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Stevens, Richard D.