Meeting Abstract
Many fishes are limited to marine or freshwater environments, however, roughly 250 of the nearly 30,000 teleost fishes are diadromous, or migrate between marine and freshwater during a particular stage of their life. Evolutionarily, diadromy is of interest due to its rare, yet widespread occurrence in nearly 40 families of fishes, not to mention this behavior is also found in various invertebrate families. Using a tree consisting of 7822 species of fishes with the implementation of MUSSE model in R, rates of transition in and out of diadromy to and from marine and freshwater lifestyles was tested to understand the role diadromy plays in transition between different phases. Additionally rate of diversification as a function of speciation and extinctions were examined in all three character states. Results indicate that transitions to diadromy are rare from both marine and freshwater clades, yet once acquired, diversification rates tend to be high when compared to marine fishes and equivalent or higher compared to freshwater fishes, depending on the model choice. Additionally transition out the diadromous character state occurred at a rate that was two orders of magnitude higher than transitions out of marine or freshwater to any other state. This information does not support the hypothesis that diadromy is simply an intermediate state while transitioning between freshwater and marine systems.
