Genetic connectivity in Sparisoma aurofrenatum (redband parrotfish): an unexpected journey.

Oceanic biogeographic barriers disrupt population connectivity and are produced by currents, changes in sea surface temperature, geomorphology, upwelling and resource availability, among others. Their impacts can vary in magnitude depending on their duration and degree of obstruction. Knowing the effects of biogeographic barriers on genetic connectivity has important implications in management and species conservation. To estimate the effects on the genetic connectivity of marine fishes, Sparisoma aurofrenatum was chosen as our model to test the influence of three different barriers in the southern Caribbean as listed: the Panamá-Colombia countercurrent, the Magdalena freshwater outlet, and la Guajira coastal upwelling. This species of parrotfish plays an important ecological role, helping to maintain the balance between corals and macroalgae, and facilitating recruitment and coral growth. Mitochondrial DNA (control region) was used in 88 individuals sampled between July and October 2015, along four localities across the putative barriers in the southern Caribbean. Our results point to discrete populations connected by an asymmetrical east to west unidirectional flow, a high effective population size with a population expansion during the last glacial period. Thus, the three southern Caribbean barriers in this species appear to be effective in isolating populations, but permeable to immigration. [ABSTRACT FROM AUTHOR]