Fine mapping and evolution of the major sex determining region in turbot (Scophthalmus maximus).
Bottom Line: Six genes were located to the SD region, two of them associated with gonad development (sox2 and dnajc19).Genetic diversity and differentiation for 25 LG5 genetic markers showed no differences between males and females sampled from a wild population, suggesting a recent origin of the SD region in turbot.We also analyzed associations with markers of the most relevant sex-related linkage groups in brill (S. rhombus), a closely related species to turbot; the data suggest that an ancient XX/XY system in brill changed to a ZZ/ZW mechanism in turbot.
Affiliation: Departamento de Genética, Facultad de Biología (CIBUS), Universidad de Santiago de Compostela, Avda. Lope Gómez de Marzoa, 15782 Santiago de Compostela, Spain.Show MeSH
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Mentions: We evaluated genetic diversity on LG5 in a wild population of 48 males and 48 females, using 28 markers covering 71.2 cM between Sma-E79 and Sma-USC10 (Figure 1). Two markers, fkbp2 and Sma-SNP46, were discarded because of very low diversity (He < 0.01) and one (ScmM1) because of doubtful genotyping, leaving a density of one marker per 2.8 cM in LG5, and one per 0.4 cM in the SD region between SmaUSC-E30 and SmaSNP_31 (Figure 1). Neither He nor A differed between males and females (Mann-Whitney test P = 0.900 and 0.803, respectively; Figure 4, A and B). The average genetic diversity, however, was significantly less in the proximal than the distal region for all the markers (He: 0.473 vs. 0.689; A: 4.000 vs. 8.182 Mann-Whitney tests: P = 0.002 and 0, respectively) (Figure 4, A and B), or when only microsatellites were considered (proximal vs. distal regions: He 0.567 vs. 0.723, P = 0.004; A: 5.826 vs. 8.708, P = 0.005).
Affiliation: Departamento de Genética, Facultad de Biología (CIBUS), Universidad de Santiago de Compostela, Avda. Lope Gómez de Marzoa, 15782 Santiago de Compostela, Spain.