Global biogeographic regions for ants have complex relationships with those for plants and tetrapods

Abstract

On a global scale, biodiversity is geographically structured into regions of biotic similarity. Delineating these regions has been mostly targeted for tetrapods and plants, but those for hyperdiverse groups such as insects are relatively unknown. Insects may have higher biogeographic congruence with plants than tetrapods due to their tight ecological and evolutionary links with the former, but it remains untested. Here, we developed the first global regionalization for a major and widespread insect group, ants, based on the most comprehensive distributional and phylogenetic information to date, and examined its similarity to regionalizations for tetrapods and vascular plants. Our ant regionalization supported the newly proposed Madagascan and Sino-Japanese realms based on tetrapod delineations, and recovered clusters observed in plants but not in tetrapods, such as the Holarctic and Indo-Pacific realms. Quantitative comparison suggests strong associations among different groups—plants showed a higher congruence with ants than with tetrapods. These results underscore the wide congruence of diverse distribution patterns across the tree of life, but the similarities shared by insects and plants that are not captured by tetrapod groups. Our analysis highlights the importance of developing global biogeographic maps for insect groups to obtain an unbiased geographic picture of life on Earth.