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
Related in: MedlinePlus
Mentions: We combined segregation data for adjacent markers in LG5 from previous reports (Hermida et al. 2013) and our new work for the nine mapping families (HF, DF, and QF1−QF7). Information for a given interval generally was available from only a single family, but data for 14 markers identified consistent differences along LG5 (Figure 3). The RF over common intervals in females was greater than in males (f/m ratio 1.8:1, slightly greater than the 1.6:1 observed for the whole turbot map; Bouza et al. 2012). A major difference, however, was observed between the proximal (36.2 cM) and distal (23.4 cM) regions (Figure 3). In the proximal region, the average RF for all marker pairs, weighted by the map lengths, was identical in the two sexes, but in the distal region it was nearly four times greater in females (3.6:1). Within the proximal region, differences between males and females, and between different families, were observed within the main SD region (Figure 1 and Figure 3), whereas the remaining intervals recombined at similar rates in both sexes. In the distal region, a first subregion (between YSKr50 and Sma-USC198) showed no recombination in males, whereas in females recombinants were found for all marker pairs, and, in the terminal subregion, the RF was much greater in females than in males. These differences between sexes may be due to chromosome rearrangements as suggested previously (Martínez et al. 2009), but the information is not yet sufficient to be conclusive.
Affiliation: Departamento de Genética, Facultad de Biología (CIBUS), Universidad de Santiago de Compostela, Avda. Lope Gómez de Marzoa, 15782 Santiago de Compostela, Spain.