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- Mitochondrial DNA reveals a mosaic pattern of phylogeographical structure in Atlantic and Mediterranean populations of anchovy (Engraulis encrasicolus)Publication . Magoulas, A.; Castilho, Rita; Caetano, Sandra; Marcato, S.; Patarnello, T.This study extends the geographic coverage of a previous study of mitochondrial DNA restriction fragment length polymorphism in European anchovy. Both studies together include 24 samples representing 17 localities extending from the Black Sea, through the Mediterranean Sea to the eastern Atlantic as far south as Dakar, Senegal. Eighty-eight haplotypes deWne two clades (A and B) separated by 3.2% sequence divergence. Clade A has a star-like genealogy indicative of a recent population expansion. Clade B has a more complex genealogy, consisting of several haplotypes at intermediate frequencies. The distributions of these clades consist of a mosaic with abrupt changes between some areas and gradients between other areas. Clade A predominates the Black and Aegean seas, but is present throughout the Mediterranean. Unexpectedly, new data show that clade A is also at a high frequency in the Atlantic, from Portugal to at least Senegal. Overall, the level of genetic diVerentiation among populations is high (FSTD0.148, p<0.0001), with the greatest diVerences between basins. AMOVA reveals four main geographical groups: Atlantic, central Mediterranean, Aegean Sea, and Black Sea. Mismatch distribution clearly indicates historical bottleneck and population expansion for clade A, while for clade B such evidence is equivocal. This diVerence may reXect a range expansion for both clades, but with higher gene Xow (Nm values) between demes for clade A. Both contemporary and historical processes are important in shaping the complex genetic population structure of European anchovy.
- Differential population structuring of two closely related fish species, the mackerel (Scomber scombrus) and the chub mackerel (Scomber japonicus), in the Mediterranean SeaPublication . Zardoya, R.; Castilho, Rita; Grande, Cristina; Favre-Krey, L.; Caetano, Sandra; Marcato, S.; Krey, G.; Patarnello, T.Population genetic structures of the mackerel (Scomber scombrus) and chub mackerel (Scomber japonicus) were studied in the Mediterranean Sea. Fragments of 272 bp (S. scomber) and 387 bp (S. japonicus) of the 5′ -end of the mitochondrial control region were sequenced from spawning individuals collected off the coasts of Greece, Italy, Spain, and Portugal. High levels of mitochondrial control region haplotypic diversity (> 0.98) were found for both Scomber species. Nucleotide diversity was higher in the mackerel (0.022) than in the chub mackerel (0.017). Global F ST values were also higher and significant in the mackerel (0.024, P < 0.0001) as opposed to the chub mackerel (0.003, P > 0.05). Molecular variance analyses showed differential genetic structuring for these two closely related species. There is extensive gene flow between Mediterranean Sea and Atlantic Ocean populations of chub mackerel, which are organized into a larger panmictic unit. In contrast, Mediterranean Sea populations of mackerel show some degree of genetic differentiation and are structured along an east–west axis. The analysed eastern Mediterranean Sea mackerel populations (Greece, Italy) are clearly separated from that of the western Mediterranean Sea (Barcelona), which forms a panmictic unit with eastern Atlantic Ocean populations. The genetic structures of both species showed asymmetric migration patterns and indicated population expansion.