Filogeografia de Entomacrodus vomerinus (Valenciennes, 1836) (Teleostei: Blenniidae) na província Atlântico Sudoeste Tropical: existe conectividade entre habitats oceânicos e continentais?

Abstract

Entomacrodus vomerinus (Valenciennes, 1836) is a demersal fish endemic to the Tropical Southwestern Atlantic province, inhabiting tide pools at continental and oceanic reef environments. Because of the small home range (about 4m2) and adhesive eggs, low population connectivity is expected in the absence of pelagic larvae. The objective of this study was to evaluate the genetic connectivity of the species using three molecular markers and a phylogeographyc approach, providing a framework for conservation studies by determing evolutionary significant units (ESU). Eighty-five individuals from four ecoregions sampled from 2011 to 2014 were included, two composed of oceanic islands – Sao Pedro and Sao Paulo Islands (SS), and Fernando de Noronha (FE) and Atoll das Rocas (AR) - and two of the continent - Northeastern Brazil (coast of Rio Grande do Norte [RN]) and Eastern Brazil (Bahia coast [BA]). The analysis of molecular variance (AMOVA) for mitochondrial genes Cytochrome C Oxidase subunit I (COI) and Cytochrome b (CYTB) revealed three haplogroups (SS / FE + AR / RN + BA). The Bayesian analysis of population structure (BAPS) recovered a similar scenario, indicating three genetic groups in COI and CYTB and four groups for the nuclear rhodopsin gene (RHOD), indicating higher rates of genetic connectivity on this marker as two groups occur in al localities. The FST paired for the three markers indicated that gene flow between the island and mainland habitats is restricted, especially between the SS and all the other locations. The Mantel test refuted an isolation by distance scenario. The natural history of E. vomerinus revealed three ESUs, that agrees with biogeographic subdivisions. The recovered genetic structure can be attributed to passive larval dispersal during Pleistocene interglacial periods and by ocean currents, followed by isolation of individuals in the islands. Gene flow can currently be reduced due to specific ecological characteristics of each ecoregion that prevent the arrival and settlement of larvae in other locations, and larval retention in SS.