Genetic diversity and population structure of the blue jack mackerel Trachurus picturatus across its western distribution

Abstract

Blue jack mackerel Trachurus picturatus collected at six sampling locations of the north-east Atlantic Ocean (Azores, Madeira, Canaries, and Matosinhos, Peniche and Portimão, mainland Portugal) and one location in the Mediterranean (Sicily), were used to examine the genetic structure of this species. Three mitochondrial gene regions (cytochrome c oxidase subunit I, cytochrome b and control region) were used to study the genetic structure of the species in Macaronesia, as well as to compare the genetic diversity of this region with published results from its eastern distribution. All markers indicated the absence of genetic structure among populations, with high indices of genetic diversity. These results suggest that the species went through a bottleneck event, followed by a recent population expansion. Moreover, the comparison with previously published results from the T. picturatus Mediterranean distribution suggests the existence of a single panmictic population throughout the species´full range. This was, however, an unexpected result since other methodologies have shown the presence of, at least, three different population-units in the NE

Genetic analysis provides insights into species distribution and population structure in East Atlantic horse mackerel (Trachurus trachurus and T. capensis)

“…This aligns with the previous T. trachurus study by Kasapidis & Magoulas (), which found no significant structure across a more extensive sampling of NE Atlantic and Mediterranean waters using four of the microsatellites employed here. Genetic cohesion between Atlantic and Mediterranean samples is also described for other horse mackerel species and indicates that the Almeria‐Oran frontal system is not a prominent phylogeographic break in this group (Comesana et al ., ; Moreira et al ., ). Nuclear F ST tests performed for both the null allele corrected and the subset of HWE conforming loci and mtDNA Φ ST broadly supported a lack of differentiation of the Ghana sample from the other T. trachurus samples.…”

“…Nuclear F ST tests performed for both the null allele corrected and the subset of HWE conforming loci and mtDNA Φ ST broadly supported a lack of differentiation of the Ghana sample from the other T. trachurus samples. Although there was a gap in our sampling between Ghana and Europe, high gene flow between European and north‐west African sites is also suggested for the blue jack mackerel ( T. picturatus ) (Moreira et al ., ). The available data therefore indicate that T. trachurus exhibits high gene flow and an absence of genetic structure across most of its sampled range to date.…”

“…Despite signatures of historical population size fluctuations all samples exhibited similar levels of genetic variation that were comparable to levels in other small pelagic fish species ( Sardinella aurita : Tringali & Wilson, ; Engraulis encrasicolous : Silva et al ., ; Engraulis japonicus : Liu et al . ; and T. picturatus : Moreira et al ., ). Although fisheries induced loss of genetic variation, as observed in other taxa (Cimmaruta et al ., ), cannot be discounted the data indicate that local populations retain high levels of genetic variation and if current effective population sizes are maintained genetic drift alone will be insufficient to erode variation.…”

“…The current management of the species as distinct northern and southern BUS stocks therefore represents a potential misalignment between management and population boundaries(Reiss et al 2009). mtDNA and microsatellites revealed no significant genetic structuring among the NE Atlantic and Mediterranean T. trachurus samples Moreira et al, 2019)…”

Population structure of the chub mackerel (Scomber colias) in the North-east Atlantic inferred from otolith shape and body morphometrics

“…Although molecular markers, namely mtDNA, show weak genetic structure among marine pelagic fish (Chlaida et al 2009;Kasapidis et al 2012;Moreira et al 2019b), a single stock of S. colias has been considered until now for the Northeast Atlantic (Scoles et al 1998;Zardoya et al 2004). However, the present results showed significant regional differences in body geometric morphometrics and otolith-shape analyses of individuals collected in the North-east (ICES IXa and X) and eastern Centre (CECAF 34.1.2) Atlantic fishing areas for the species.…”