Investigation of the Vitória-Trindade chain as a barrier to gene flow in Colpomenia sinuosa (Ectocarpales, Phaeophyceae)

Abstract

Barriers to gene flow are often represented by historical geological vicariant events that interrupt gene flow between populations, promoting genetic differentiation. Barriers to gene flow are intrinsically associated with the formation and maintenance of most phylogeographical breaks observed until current days. The Vitória-Trindade seamounts chain (latitude 20.5º S) is one of the main geographic barriers to gene flow for marine organisms along the Brazilian coast. This region split the Brazilian coast into two sections, especially during the Quaternary maximum glacial periods, when the sea level was lower than today. Thus, the objectives of this project are to investigate the effects of Vitória-Trindade seamounts chain as a barrier to gene flow using the brown macroalgae Colpomenia sinuosa as a model organism. We will also estimate the effects of sea currents and other abiotic, local and regional processes (e.g., climate, estuaries), which promote genetic isolation in structuring and maintaining the genetic diversity of C. sinuosa populations. For this, the single nucleotide polymorphism molecular markers (SNPs) and metabolite profile (metabolomics) will be used. These represent relatively new technologies and not yet applied to Brazilian marine macroalgae and enhance enough resolution to identify populational differences in ecological and evolutionary time scales. We will carry out collections with a high degree of spatial resolution along the region where the Vitória-Trindade seamounts chain joins the Brazilian continental shelf, and perform phylogeographical analyzes to understand the genetic variation distribution of the species, along with ecological niche modeling (ENM) to estimate the distribution of the species in space and time, especially at the last glacial maximum. Still, we will test the populations connectivity through dispersion by sea currents by modeling ocean currents. In this way, we expect to identify, quantify and describe the main geographic barrier to gene flow identified between the States of Bahia and Espírito Santo for the species Colpomenia sinuosa, in addition to identifying the historical and contemporary processes responsible for its formation and maintenance. Considering that sympatric species often share the same evolutionary history, our results will serve as a model for future tests of phylogeographic agreement in the region of Cadeia Vitória and Trindade. (AU)