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.