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

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.Ambientes marinhos costeiros são caracterizados pela falta de barreiras físicas evidentes e ausência de isolamento geográfico, sendo difícil compreender como diferentes linhagens podem surgir e ser mantidas nestes ambientes. A identificação de barreiras permeáveis é um passo importante para a compreensão do fluxo gênico em ambientes marinhos. Os bagres marinhos da família Ariidae são um grupo demersal, com mecanismos de retenção larval e sem comportamento migratório ou estágio larval pelágico, representando um grupo potencialmente útil para a compreensão de processos históricos de especiação alopátrica no ambiente marinho. No presente estudo, duas linhagens do bandeirado ou bagre de fita, Bagre bagre, são reconhecidas com base na completa segregação mitocondrial e morfológica. Uma linhagem é encontrada da Venezuela à costa norte do Brasil, incluindo a costa nordeste semi-árida, enquanto a segunda linhagem é encontrada na costa leste e sudeste do Brasil, incluindo a costa nordeste úmida. Com base na área de distribuição, habitat preferencial e a variabilidade genética, inferências são feitas em relação à biogeografia e demografia das duas linhagens na costa do Atlântico da América do Sul.

Redescription ofNotarius grandicassisandNotarius parmocassis(Siluriformes; Ariidae), with insights into morphological plasticity and evidence of incipient speciation

“…31-32), and at different stages of ontogenetic development (Figs 30,32,(33)(34)(35). The absence of any significant genetic differentiation between Notarius grandicassis and Notarius parmocassis species are the result of a recent speciation process, resulting from occurrence of the species in different geographic areas with distinct environmental conditions and selective pressures (da Silva et al, 2016), in the Atlantic Ocean of South America (Fig. 36).…”

“…The lack of genetic differentiation between Notarius grandicassis and N. parmocassis, despite the existence of morphological differences, is interpreted here as a consequence of the evolutionary history of these species, which are found in different geographic areas with distinct environmental conditions (da Silva et al, 2016). However, little is known of the differentiation of the coastal and estuarine fish fauna of the Atlantic coast of South America and environmental factors that can contribute to this differentiation (see Santos, Hrbek, Farias, Schneider, & Sampaio, 2006;da Silva et al, 2016).…”

“…The study of da Silva et al (2016) is one important contribution, which recognized the existence of two distinct genetic and morphological lineages of Bagre bagre (sensu Acero, 2003), with an estimated age of 1.8 my, on the Atlantic coast of South America. The differentiation of these lineages has been attributed to the glacial cycles of the early Pleistocene, with salinity and other environmental variables that characterize the area between the Amazon-Orinoco plume and the north-eastern extreme of Brazil being identified as the principal factor determining the current isolation of these, as for the other ariids found on the Atlantic coast of South America (da Silva et al, 2016).…”

Isotopic niche of the catfishes Bagre bagre and Genidens barbus in a coastal area of south-eastern Brazil

“…Among this primarily freshwater fish group, the family Ariidae is marine, generally more abundant in shallow coastal waters, in muddy or sandy bottoms (Marceniuk 2005, Silva et al 2016. In general, the marine catfishes seek out river mouths and coastal lagoons during the spawning period, and they show reproductive adaptations as mouthbrooding (Chaves & Vendel 1996, Ferraris Jr. 2007).…”

<b>Feeding habits and behaviour of <I>Bagre bagre</I> and <I>Genidens barbus</I>, two ariid catfishes (Pisces: Siluriformes) from southeastern Brazil</b>

“…The family Ariidae inhabits marine waters and is abundant in coastal areas associated with muddy or sandy bottoms (Marceniuk 2005;Silva et al 2016), seeking out rivers and coastal lagoons during the spawning period (Ferraris 2007).…”