Ant diversity and species assemblages along an elevational gradient in the arid area of Central Iran

Abstract

Ants (Hym., Formicidae) have been recognized as vital components of arid ecosystems. Determining the diversity patterns of ants and the ecological factors behind these patterns is expected to improve our understanding of the functioning of arid ecosystems. Here, we explored patterns of ant species diversity and community composition along an elevational gradient (800 to 2800 m) in the arid area of Central Iran. The elevational gradient in ant diversity and the effects of environmental factors on various indices of ant diversity and species composition were investigated using generalized linear mixed models and variance partitioning analysis. We recorded 34 ant species of 12 genera and 8 tribes from 120 surveyed quadrats. Climate variables were the most important predictors of ant community structure. Indices of ant alpha diversity including Hill numbers and taxonomic diversity increased with elevation. Hill numbers were negatively influenced by temperature, while they were positively affected by precipitation. The observed diversity pattern could be explained by the diversity-productivity hypothesis. In our study area, the maximum primary productivity and consequently the maximum species diversity occurred at high elevations, where precipitation is high and temperature is lower than the extremes that could limit plant productivity. Ant assemblages are expected to become increasingly composed of warm-tolerant species in response to warmer and drier conditions driven by climate change. The distribution of species with lower heat tolerance will be limited to high-elevation areas in Central Iran. These areas could act as refuges for ants and should be considered priorities for conservation.