Microsatellite DNA reveals low genetic differentiation among chub mackerel (Scomber colias) sampled in Atlantic and Mediterranea

Abstract

The family Scombridae contains 15 genera and about 51 species of epipelagic and migratory marine fish. One of the most representative species of this family is the mackerel (Scomber colias, Gmelin, 1789), which lives in warm waters off the coast of the Atlantic Ocean and Mediterranean Sea but is also prevalent in the African coast from Morocco to South Africa. Mackerel is an economically and ecologically world interest species, which in 2011 was in the fifth position of the 25 species most captured, reached nearly 1.72 million tons of global captures in the world (FAO, 2011). The main objective of this work is to assess genetic diversity and population genetic structure of mackerel (Scomber colias) comparing Atlantic and Western Mediterranean. Was performed using genetic markers microsatellites described by Yagishita and Kobayashi, 2008. The results show a high genetic diversity in each population, revealing a high polymorphism and number of alleles per locus. Analyses indicated that a large genetic homogeneity existed among all Atlantic and Mediterranean populations. The low genetic differentiation between the study areas is indicative of a panmictic scenario among all natural populations of Scomber colias. The absence of correlation between the genetic distance and the geographic distance indicates that the connectivity pattern among Atlantic grounds does not fit an isolation by distance model (IBD) (Kimura and Weiss, 1964) so the Strait of Gibraltar is a communication way that allows an Atlantic-Mediterranean larval flow (Velasco et al. 2011), as well as a genetic flow between the Atlantic and the Mediterranean. There is a high gene flow between populations but a slight restriction to this flow was observed at the eastern most side of the Alboran Sea what suggests that the Almeria–Oran Oceanographic Front is an effective barrier keeping apart populations of Atlantic and Almeria of Melilla-Vilanova.