Untangling extant biodiversity in Hydroporini

Abstract

Aquatic beetles can be characterized based on the habitats where they live, with a main division between species living in standing water or species living in running waters. Both habitat types present differences based on their physical and chemical characteristics, leading to different ecological dynamics at geological scale, in essentially long-term habitat stability. Small standing water environments, where aquatic beetles are usually found, are usually filled up by sediments in decades, whilst running water environments are stable and they are connected with the drainage network, even when they sometimes dry up seasonally. Some studies had shown that one of the consequences of living in one kind or the other is a difference in range size linked to their dispersal capabilities, with standing water species having broader geographical ranges than running water species. It has been hypothesizing that dispersal abilities may affect gene flow and turnover, but there is a lack of knowledge of how these differences affect long-term diversification. Hydroporini is a speciose tribe containing ca. 680 species living in both habitats, making them and ideal group to study diversification. We built a phylogeny of Hydroporini combining 5 genes obtained with sanger sequences plus 69 mitochondrial genomes. In total, 473 terminals representing species were used. Ecological data were obtained by bibliographic revision plus own collected information in the field. Phylogeny and habitat type evolution were reconstructed using Bayesian inference. Diversification rates were calculated using Bayesian Analysis of Macroevolutionary Mixtures (BAMM) and method of moments (MM). Preliminary results suggest that the most recent common ancestor of Hydroporini was reconstructed with a preference for running water, with multiple shifts to standing waters. We also found several significant diversification shifts across the phylogeny, and a clear pattern of gradual accelerated speciation.