Tempo and mode of diversification in Adontosternarchus (Gymnotiformes, Apteronotidae): a molecular approach

Abstract

The Neotropical region harbours the largest taxonomic diversity for several aquatic and terrestrial faunal groups globally; the most recently updated numbers for fishes reaches almost 8,000 species. Due to its megadiversity, investigation of the tempo and mode of diversification as well as other evolutionary aspects of these groups represent a major challenge for scientific researchers. Among the limiting factors for studying these topics are: 1. Poorly resolved taxonomic and phylogenetic relationships within groups; 2. Inadequate data about habitat, ecology and geographical distribution; 3. Absence, or incomplete data on fossil records; and 4. Incomplete knowledge about geological development of the river basins in the Neotropical region. Adontosternarchus, is a monophyletic, well delimited genus of electric fishes with a well-defined phylogenetic position in the family Apteronotidae. In addition, data on species ecology and geographical distribution are readily available. This makes Adontosternarchus a model group for studying species diversification in the Neotropics. Currently six species are recognized in the genus, distributed in channels of large rivers in the lowlands of the Amazon and Orinoco basins. This proposal aims to build hypotheses of phylogenetic relationships for all species of Adontosternarchus based on ddRADseq and Cytb. In turn, the tree topology will used to study: 1. Diversification rates in Adontosternarchus; and 2. Test taxonomic boundaries of target species (e.g., A. balaenops). Based on the diversification scenarios obtained for Adontosternarchus, we will answer several questions related to the evolution of aquatic organisms on a continental scale. This research proposal is linked to the thematic project "Diversidade e Evolução de Gymnotiformes" (International cooperation FAPESP/Smithsonian Institution; Process n. 2016/19075-9, valid up to June 2022). (AU)