Molecular genetic, life‐history and morphological variation in a coastal warm‐temperate sciaenid fish: evidence for an upwelling‐driven speciation event

Abstract

Aim The Benguela Upwelling System (BUS) is a major biogeographical boundary in the south‐eastern Atlantic, but little is known of the effect of historical permeability of the barrier on species distributed across the region. We used phylogenetic, life‐history and morphological analyses to test the influence of regional oceanographic features on genetic divergence, evolutionary history and ecological divergence in a warm‐temperate fish, Atractoscion aequidens. Location Benguela Current, south‐eastern Atlantic Ocean. Methods Individual At. aequidens were analysed for molecular (N = 35), biological (N = 81) and morphological (N = 282) differentiation across the BUS region. To compare patterns of genetic divergence, we also included analyses of individuals sampled from three related Argyrosomus species occurring in the area. Results Atractoscion aequidens comprises two deeply divergent lineages (average mtDNA genetic distance p = 0.049), which are separated by the boundary between the northern and southern Benguela subsystems. Divergence time was estimated at 2–3 Myr. Life‐history traits, such as maximum size, growth rate and size and age at maturity, differed significantly between the two lineages, but morphological features did not. Divergent life‐history traits appear to be associated with the evolution of migratory behaviour in the southern population, and thus ecological diversification across the Benguela region. Main conclusions The oceanographic features of the BUS constitute an impermeable barrier to the dispersal of At. aequidens across the region. The estimated time since most recent common ancestor (TMRCA) points to the strengthening of the upwelling system in the last 2 Myr as the most likely mechanism driving isolation. However, the BUS is known to have periodic disruptions, which have mediated dispersal in multiple taxa. Therefore, the depth of genetic divergence and the presence of different life‐history traits between the two lineages suggest that ecological divergence may have played a role in maintaining the observed isolation. Based on genealogical, geographical and ecological concordance, we suggest that At. aequidens is composed of two sibling species in the Benguela region and a full taxonomic revision of the genus is required.

Integrated genetic and morphological data support eco‐evolutionary divergence of Angolan and South African populations of Diplodus hottentotus

“…A focus of this study was to assess evidence for divergence between conspecific populations of D. hottentotus in Angolan and South African waters. In line with a priori predictions, based on observations in other coastal fish species of evolutionary independence of populations across the Benguela Current system (Henriques, ; Henriques et al, , , ), high levels of genetic and morphological divergence between D. hottentotus populations in the two regions were found, which should prompt a taxonomic revision of this species.…”

Phylogeny of the Sepia officinalis species complex in the eastern Atlantic extends the known distribution of Sepia vermiculata across the Benguela upwelling region

“…vermiculata and S. hierredda in order to appropriately conserve the biodiversity of this region and negate the detrimental impacts of indiscriminate harvesting. Finally, we reveal subtle patterns of phylogenetic diversification between S. vermiculata from South Africa and Angola, indicating that, as for many marine teleosts (Henriques et al 2014(Henriques et al , 2016, the Benguela upwelling region constitutes a biogeographic barrier to dispersal for the Sepiidae.…”

Taxonomical study of Trichomycterus (Siluriformes: Trichomycteridae) from the Ribeira de Iguape River basin reveals a new species recorded in the early 20th century

“…Therefore, the genetic similarity between Trichomycterus alternatus and T. jacupiranga may be due to a recent speciation event ( e.g ., incomplete lineage sorting) or, alternatively, an older event with posterior introgression ( e.g ., mitochondrial introgression). Thus, these species may not be distinguished by mitochondrial molecular data due to the lack of reciprocal monophyly between them, as previously reported for other Neotropical freshwater fish groups with a complex taxonomic history (Pereira et al , ; Costa‐Silva et al ., 2015; Henriques et al , ). There are cases in which mitochondrial markers failed to distinguish taxa traditionally recognized as separated species based on morphology (Pedraza‐Marrón et al , ).…”

“…Neotropical freshwater fish groups with a complex taxonomic history Costa-Silva et al, 2015;Henriques et al, 2016).…”