Differences in functional guild responses to elevation and topography in Himalayan ant communities

We investigated the influence of small-scale topographic and associated microclimatic drivers on the elevational patterns of functional alpha and beta diversity in ant communities of eastern Himalayas. Ants were sampled along three elevational transects spanning [~]1000-2000 m on two nearby mountain slopes, but differing in aspect, inclination and summit height. Ant genera were quantified at the quadrat level, yielding an abundance of 3090 genus-quadrats (from 22577 individuals in 1215 quadrats), almost evenly split between the two mountain slopes. Each ant was assigned to guilds along functional axes of thermal niche, trophic position and competitive abilities. Comparative analyses of functional diversity profiles along the two mountain slopes revealed no differences in the composite multi-guild alpha and beta diversity but significant differences amongst individual guild profiles. Seven of the eleven functional guilds showed strong elevational trends along the steeper north-facing slope, compared to only two of eleven on the shallower south-facing slope. These results indicate that similar functional space can be maintained despite taxonomic turnover within guilds or shifts in their relative abundances highlighting the influence of fine-scale topographic variation on community assembly. Alternatively, these findings demonstrate that the pattern of multivariate functional diversity across elevation does not necessarily provide an understanding of changing composition of the communities therein.