Heraty, J. | Search bioRxiv

bioRxiv2026

Global homeostatic forces shape the composition of a hyperdiverse tropical insect fauna

Despite comprising the bulk of terrestrial biodiversity, we know surprisingly little about insect faunas, particularly in the tropics. Here, we characterize the insect fauna of Madagascar, a global biodiversity hotspot, based on extensive DNA metabarcoding of Malaise trap and leaf litter samples. We estimate that the fauna comprises at least 250,000 species, only 5% of which are currently recorded. The ecological and taxonomic composition is surprisingly similar to that of temperate forests. We show that this is likely caused by global homeostatic forces shaping net diversification rates after colonization of Madagascar rather than by the composition of colonizing lineages. Features differing from temperate forests include the dearth of parasitoids and richness of beetles. Understanding the forces shaping these patterns is key in sustainable management of tropical insect faunas.

evolutionary biology↗

bioRxiv2022

Global convergence of dominance and neglect in flying insect diversity

Most of arthropod biodiversity is unknown to science. For this reason, it has been unclear whether insect communities around the world are dominated by the same or different taxa. This question can be answered through standardized sampling of biodiversity followed by estimation of species diversity and community composition with DNA sequences. This approach is here applied to flying insects sampled by 39 Malaise traps placed in five biogeographic regions, eight countries, and numerous habitats (>220,000 specimens belonging to >25,000 species in 463 families). Unexpectedly, we find that 20 insect families account for >50% of local species diversity regardless of continent, climatic region, and habitat type. These consistent differences in family-level dominance explain two-thirds of variation in community composition despite massive levels of species turnover, with most species (>97%) in the top 20 families encountered at a single site only. Alarmingly, the same families that dominate global insect diversity also suffer from extreme taxonomic neglect with little signs of increasing activities in recent years. Tackling the biodiversity of these "dark taxa" thereby emerges as an urgent priority because the arthropod groups comprising most of the global flying insect diversity are particularly poorly known.

ecology↗