Meeting Abstract
Understanding causes for the great unevenness in biodiversity across Earth and the Tree of Life is a major goal of evolutionary biology. The invasion of new habitats such as coral reefs in the ocean or streams on land have been hypothesized as drivers of diversification because they provide ecological opportunity by reducing competition. If habitat transitions provide ecological opportunity, then rates of diversification should be greatest in clades with an evolutionary history of shifts between marine and freshwater habitats. Here we use a time-calibrated, 1006 taxon megaphylogeny of the globally distributed and ecologically diverse Gobiiformes fishes, constructed from a partial matrix of 33 gene sequences to test the hypothesis that habitat shifts drive diversification. We use macroevolutionary modeling of diversification rates and ancestral state reconstruction of habitats to identify lineages in the Gobiiformes radiation that have undergone rapid speciation in marine and freshwater environments. We find strong evidence for diversification rate heterogeneity in Gobiiformes fishes, characterized by a low background rate for non-goby lineages followed by rate increases at the root of the goby clade and several freshwater and coral reef goby lineages. In contrast, we found no variation in diversification rates among the marine cardinalfishes or freshwater sleepers, which supports the hypothesis that transitions between habitats drive diversification.
