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Abstract: Seed dispersal by ants is ecologically important and geographically widespread as 20–50% of all herbaceous species in eastern deciduous forests are dispersed by ants, but we know little about how or why such interactions vary geographically. In this paper, we examined variation in seed dispersal by ants along an extensive elevational gradient (256–2025m) in the Great Smoky Mountains National Park, USA. Specifically, we asked whether variation in ant community composition affected seed removals and seed dispersal distance of Trillium undulatum and Hexastylis arifolia, two common understory herbs found throughout the southern Appalachian Mountains. We also examined variation in myrmecochore abundance, specifically Trillium spp. and H. arifolia, along the same elevational gradient. Measures of ant community and climate variables strongly covaried with elevation, while Trillium species richness and abundance did not. We found that seed removals decreased with elevation, but seed dispersal distance did not depend on elevation. The most important variables predicting seed removals were average annual temperature and the abundance of Aphaenogaster rudis, both of which varied along the elevational gradient. Seed dispersal by ants did not depend on ant community composition, but was dominated by one species, A. rudis, which occurred at every site and removed the vast majority of all observed seeds in this study. Though the ant fauna in the Great Smoky Mountains National Park is diverse, dispersal of T. undulatum and H. arifolia, and likely other myrmecochores, is driven by one ant species, A. rudis. [Copyright &y& Elsevier]

We report on a systematic survey of the ant fauna occurring in hardwood forests in the Great Smoky Mountains National Park. At 22-mixed hardwood sites, we collected leaf-litter ant species using Winkler samplers. At eight of those sites, we also collected ants using pitfall and Malaise traps. In total, we collected 53 ant species. As shown in other studies, ant species richness tended to decline with increasing elevation. Leaf-litter ant assemblages were also highly nested. Several common species were both locally abundant and had broad distributions, while many other species were rarely detected. Winkler samplers, pitfall traps, and Malaise traps yielded samples that differed in composition, but not richness, from one another. Taken together, our work begins to illuminate the factors that govern the diversity, distribution, abundance, and perhaps rarity of ants of forested ecosystems in the Great Smoky Mountains National Park. [ABSTRACT FROM AUTHOR]

An ever-increasing number of studies use tools from community phylogenetics to infer the processes underlying the assembly of communities. However, very few studies simultaneously use experimental approaches to characterize the ecological niches of species and directly assess the importance of these structuring processes. In this study, we developed an experimental approach for quantifying the use of four types of food resources and three habitat templets in temperate forest ant assemblages. We then used null models to assess whether niches overlapped more or less than expected by chance. Finally, we integrated comparative phylogenetic methods with experimental data on niche use to assess the degree of phylogenetic signal in several key components of the niche. We found that niche filtering, rather than partitioning, was the predominant structuring force. Niche filtering resulted from conservatism in habitat niches in evolutionary time and limitations in the availability of food resources in ecological time. Our study thus supports the idea that similarities in niches among species, rather than the differences, drive the assembly of ant communities., (© 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.)