Data from: Ecological character displacement among Nothobranchius annual killifishes in Tanzania

<p>Divergent ecological character displacement (ECD) is the competition-driven divergence in resource use-related phenotypic traits between coexisting species. It is considered one of the primary drivers of ecological diversification and adaptive radiation. We analyzed phenotypic and ecological variation in two African annual killifish species of the genus <em>Nothobranchius</em>; <em>N. eggersi</em> and <em>N. melanospilus</em> in sympatry and <em>N. melanospilus</em> in allopatry. Our aim was to test if allopatric and sympatric populations of <em>N. melanospilus</em> differ morphologically from each other and from <em>N. eggersi</em>, and examine if these differences are consistent with the predictions of ECD. We find that sympatric <em>N. melanospilus</em> differ from allopatric <em>N. melanospilus</em> and differ from <em>N. eggersi</em> more strongly than the latter. Our data satisfy four criteria for demonstrating ECD: Differences in phenotypes between allopatric and sympatric <em>N. melanospilus</em> are greater than expected by chance; the divergence pattern between allopatric and sympatric <em>N. melanospilus</em> results from an evolutionary shift rather than from ecological sorting; morphological differences observed reflect differences in resource use and, lastly, sites of allopatry and sympatry do not differ in food resource availability or other ecological conditions. Our results suggest that competition is the main driver of the observed divergence between two <em>N. melanospilus </em>populations.</p>