An empirical test of mid-domain effect using Korean ant richness

The mid-domain effect is a diversity theory, which explains prevalent diversity patterns of hump-shape patterns along altitude or latitude gradients. I tested whether patterns of ant species richness along altitudes and latitudes in South Korea can be described by this theory. Ants on 12 high mountains (>1100 m) throughout South Korea (from 33°N to 38°N) were surveyed using pitfall traps at intervals of 200-300 m of altitude. The number of species collected was used to determine the species richness and the frequency (%, collected traps/total traps) was used to determine abundance. The temperatures of the sampling sites were determined from digital climate maps. Species richness of ants decreased monotonically along altitudinal and latitudinal gradients. However, species richness of cold-adapted species (highland species) showed a hump-shape pattern along altitude gradient, which could be explained by the mid-domain effect. Diversity and abundance of ant species was highly associated with temperature, which can explain the monotonic decrease of diversity. Based on these findings, I devised an integrative diversity hypothesis that explains local exclusive diversity patterns (monotonic decrease, hump-shape, and monotonic increase) and global diversity patterns (peaks in the tropical region and gradually decreases towards the poles). This hypothesis predicts the prevalence of a hump-shape pattern in hot regions and is supported by published insect data.