Early Pleistocene lineages of Bagre bagre (Linnaeus, 1766) (Siluriformes: Ariidae), from the Atlantic coast of South America, with insights into the demography and biogeography of the species

Wemerson C Da Silva,João Braullio L Sales,Juliana Araripe,Alexandre P Marceniuk

doi:10.1590/1982-0224-20150184

Wemerson C Da Silva, João Braullio L Sales + Show 2 more

Open Access

https://doi.org/10.1590/1982-0224-20150184

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Abstract

ABSTRACT Coastal and marine environments are characterized by a lack of evident physical barriers or geographic isolation, and it may be difficult to understand how divergence can arise and be sustained in marine environments. The identification of 'soft' barriers is a crucial step towards the understanding of gene flow in marine environments. The marine catfishes of the family Ariidae are a demersal group with restricted migratory behavior, no pelagic larval stages, and mechanisms of larval retention, representing a potentially useful model for the understanding of historical processes of allopatric speciation in the marine environment. In the present study, two lineages of the Coco sea catfish, Bagre bagre , were recognized from their complete segregation at both mitochondrial and morphological levels. One lineage is distributed between Venezuela and the northern coast of Brazil, including the semiarid northeast coast, while the second lineage is found on the eastern coast of Brazil, including the humid northeast coast. Based on distribution area, habitats preference, and genetic variability, inferences are made in relation to biogeography and demography of lineages in Atlantic coast of South America.

Highlights

Understanding the processes that determine the differentiation of closely related species, not delimited by obvious physical barriers, represents one of the greatest challenges in evolutionary biology (Pampoulie et al, 2004)
The two clades are supported by Maximum Likelihood (ML) (100%) and Bayesian Inference (BI) (1.0) values
The molecular analysis indicated that the separation of the two B. bagre lineages occurred approximately 1.7 mya, in the early Pleistocene

Summary

Introduction

Understanding the processes that determine the differentiation of closely related species, not delimited by obvious physical barriers, represents one of the greatest challenges in evolutionary biology (Pampoulie et al, 2004). Coastal and marine environments are characterized by a lack of evident physical barriers or geographic isolation (Bellwood & Wainwright, 2002; Rocha et al, 2002; Luiz et al, 2012), making it difficult to understand how closely related species can arise and be sustained in marine environments The identification of ‘soft’ barriers, such as the configuration of ocean currents, temperature gradients, and geomorphological features of the coastline, together with the biological characteristics of each species, is a crucial step towards the understanding the processes responsible for the differentiation and maintenance of close species in marine environment. In some parts of Brazil, such as the state of Pará, this species is targeted intensively by industrial fisheries, while in other regions, there are only limited artisanal catches (Marceniuk et al, 2015)

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