Concluding remarks
Phylogeographic studies of the Brazilian coast is still in its infancy when comparing to others biomes and areas of the world. To date, no phylogeographic review have been conducted focusing on Brazilian marine organisms. This study aimed to compile and better understand which and how major oceanographic and geographic processes found along the Brazilian coast could be acting as BGF. Amongst the recurrent geographic features, the split of the Southern Equatorial Current in two at latitude 4° S had coincided with the largest values of phylogeographic concordance, followed by a region characterized by the Vitória-Trindade seamount chain and the Doce river outflow. The Cabo Frio seasonal upwelling system, although frequently pointed in literature as potential strong BGF, had low phylogeographic concordance. On the other hand, the meeting of the Malvinas’ current with the Brazilian Current or the string of estuaries in south Brazil turned out to be a region of higher levels of BGF concordance even though such region is often not referred as a hotspot for genetic discontinuities.
According to Fine (2015) literature review and analysis, climate stability and the time–integrated area hypotheses alone are responsible for all marine and terrestrial LGD patterns observed in the world. Here we propose that a larger number of barriers to gene flow found in lower latitudes (and the processes responsible for this pattern), together with the climate stability and the time–integrated area hypotheses account for LGD, at least in the marine environment.
Due to the lack of studies at the extremes of the Brazilian coast, we could not test the effects of the Amazon river delta outflow and the Rio Grande do Sul long unconsolidated subtract extension as geographical BGF. Future phylogeographic papers will help improve the datasets and consequently the models produced in this study, allowing more spatially refined predictions of areas of high phylogeographic concordance, and the inclusion in our analyses of putative BGF located in the extreme northern and southern regions of Brazil.