2018 ESA Annual Meeting (August 5 -- 10)

COS 73-4 - Connectivity shapes local assemblages of arboreal ants

Wednesday, August 8, 2018: 2:30 PM
239, New Orleans Ernest N. Morial Convention Center
Benjamin J. Adams1, Stefan A. Schnitzer2,3 and Stephen P. Yanoviak1,3, (1)Biology Department, University of Louisville, Louisville, KY, (2)Department of Biology, Marquette University, Milwaukee, WI, (3)Smithsonian Tropical Research Institute, Balboa, Panama
Background/Question/Methods

Physical connections among habitats shape species distributions and patterns of local diversity. Such connections are particularly relevant in the forest canopy, where trees often are physically separated due to the phenomenon of crown shyness. Individual lianas (woody vines) commonly occupy multiple trees, and thus overcome crown shyness by providing a network of bridges among tree crowns. Ants are an important component of tropical arboreal communities; they contribute up to 50% of the total animal biomass and 90% of insect abundance in the canopy. However, ant workers face relatively limited options for movement within the canopy because they lack wings. To determine the relevance of the physical connections provided by lianas to local ant species richness, we surveyed ants in >200 trees in the forest of central Panama. We used a factorial design to determine how connectivity among tree crowns provided by lianas affects arboreal ant diversity. We removed lianas from individual trees and experimentally connected neighboring crowns with ropes to explicitly test the role of connectivity in structuring local (within a tree) ant communities.

Results/Conclusions

Trees naturally occupied by lianas had higher ant species richness and differed in ant species composition from trees without lianas. Three years after experimental manipulations, ant species richness declined by >20% in trees from which lianas had been removed, and ultimately fit a classic species-area curve. Supplying artificial connectivity via ropes mitigated any changes due to liana removal. Rope additions in trees occupied by lianas had no effect on arboreal ant communities. These results indicate that lianas contribute to the diversity of arboreal ant communities by increasing the physical connections among trees. Recent increases in liana abundance in tropical forests should increase ant species richness within individual trees and alter the species composition of local ant assemblages.