Distribution of ant species along an altitudinal transect in continuous rainforest in subtropical Queensland, Australia

Abstract

We present the distributions of ant species along an altitudinal gradient from 300 to 1100 m above sea level (m a.s.l.) within continuous rainforest in subtropical Queensland, Australia. Ants were collected along a single transect from four replicate plots at each of five zones of elevation (300, 500, 700, 900 and 1100 m a.s.l.) using a large array of methods targeting a wide range of microhabitats. These samples yielded a total of 170 ant species, represented by workers or ergatoid queens. A systematic ant sampling protocol, incorporating leaf litter extracts, spraying tree trunks with insecticide and hand collecting, was systematically conducted across all replicate plots in three seasons (spring, summer and autumn) enabling rigorous analysis of altitudinal patterns of species richness and assemblage structure. Species richness progressively declined with increasing altitude, with significant differences in the number of ant species between all zones except 300 and 500 m. Ant assemblages were significantly different among altitudinal zones with a progressive change in structure with increasing altitude between 300 and 900 m. Ant assemblages at 1100 m were markedly different to those at 900 m largely due to a dramatic decline in species richness rather than altitudinally restricted species. Short-term climate warming, therefore, may be of minor direct conservation concern for ants at this location. However, given the clear altitudinal signal of ant assemblages demonstrated here, ants have great potential as indicators of climate change-induced altitudinal range shifts.