Physical habitat properties shape nest selection and resource allocation in an arboreal ant community

Background/Question/Methods

Cavity-nesting arboreal ant communities present a unique opportunity to explore the exchange between resource management and competition within a physically constrained environment. Specifically, arboreal ant colonies must expand to occupy multiple nests while contending with inter- and intraspecific competition for limited nest space available within a tree crown. We mapped the nest networks and quantified individual nest contents in single-tree arboreal ant communities in over 50 poisonwood trees in the hammock forests of Key Largo, Florida. We recorded tree-level metrics such as tree size and the volume of dead wood, properties of the nest networks including physical distances and node distances among nests, and individual nest properties such as nest size and the internal ant populations they house.

Results/Conclusions

We demonstrate that the quantity of ant nests and diversity of the ant community in a tree are largely a product of tree-level metrics such as tree size and the volume of dead wood. However, after controlling for individual tree differences, arboreal ants systematically differ among different species in how they distribute their nests within a tree crown. For example, Cephalotes varians tends to minimize both physical and node distances between nests within space while Pseudomyrmex gracilis tends to disperse nests at greater distances within a tree. The quantity of both brood and adult ants within a nest is best predicted by stem volume. Collectively, these results indicate that within the highly constrained environment of a tree crown, macro (whole-tree) and and micro (stem characteristics) habitat parameters shape both diversity and nest network metrics; however, individual ant species do differ in their propensity to cluster or disperse their nests throughout a tree crown.