Population Structure of the Rockpool Blenny Entomacrodus vomerinus Shows Source-Sink Dynamics among Ecoregions in the Tropical Southwestern Atlantic

Abstract

The Tropical Southwestern Atlantic is characterized by prominent ecosystems with large-scale oceanographic complexity. Yet, the evolutionary processes underlying genetic differentiation and connectivity in this region remain largely unknown. Entomacrodus vomerinus (Valenciennes, 1836) is a demersal fish with planktonic larvae endemic to this marine province, inhabiting shallow tidal pools in continental and oceanic reef environments. We evaluated the population structure, genetic diversity and gene flow of E. vomerinus using mitochondrial data (CYTB and COI) and nuclear (rhodopsin, RHO) DNA sequences. We sampled a total of 85 individuals, comprising 46 from three oceanic archipelagos with varying distance from the coast (São Pedro and São Paulo—SS, Fernando de Noronha—FE and Rocas Atoll—RA) and 39 from two localities in northeastern Brazilian coast (Rio Grande do Norte—RN and Bahia—BA). Multilocus analysis revealed the presence of three Evolutionarily Significant Units—ESUs (SS, FE+RA, and RN+BA), which are in accordance with distinct marine ecoregions. Coalescent analyses showed that the central ESU has a larger effective population size than the other two, suggesting strong asymmetries in the genetic diversity across the species range. Moreover, they showed that gene flow is highly asymmetric, suggesting a source-sink dynamics from the central ESU into the remaining ones, in agreement with oceanic currents. Together, these results provide insights in the evolutionary mechanisms facilitating diversification in this marine province.

Integrative taxonomy reveals extreme morphological conservatism in sympatricMugilspecies from the Tropical Southwestern Atlantic

“…FISH-BCH (5-TAAACTTCAGGGTGACCAAAAAATCA) (Baldwin, Mounts, Smith, & Weigt, 2009) following the protocol of Neves et al (2016). We then performed Sanger sequencing only for the forward strand.…”

DNA barcoding reveals cryptic diversity and peculiar phylogeographic patterns in mojarras (Perciformes: Gerreidae) from the Caribbean and South-western Atlantic

“…Another issue commonly observed in studies using DNA barcodes is the restricted range of sampling from putative widespread taxa (Ward et al ., 2005; de Ribeiro et al ., 2012; Brandão et al ., 2016). This issue restrains further biogeographic inferences, including the potential detection of phylopatric evolutionary lineages (Neves et al ., 2016). In this sense, the phylogenetic and species delimitation analyses carried out in the present study were particularly informative in assessing the actual diversity in Eucinostomus , since 15 distinct lineages (MOTUs) were clearly identified.…”

Matrilineal evidence for genetic structure and Late Pleistocene demographic expansion of the Ornate goby Istigobiusornatus (Teleostei: Gobiidae) in the Persian Gulf and Oman Sea

“…Phylogeographic studies unfold the evolutionary history of species and their habitats through the estimates of historical effective population size and through the spatial association between clusters of haplotypes with ecological and geographic barriers (Avise, 2000, 2010; Avise et al., 1987; Neves et al., 2016). Without any evident physical barriers to gene flow, marine organisms with large distributional ranges are expected to present shallow genetic structuring in oceans—a panmixia paradigm (Vermeij, 1987).…”