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POSTER NO: 169 The effect of demographic differentials on the variability of Y chromosome and mtDNA in early Québec (Canada)
Alain Gagnon, Bruno Toupance, Evelyne Heyer A common challenge in population genetics is to reconstruct the evolutionary history of populations on the basis of current allele frequencies. Recently, Y chromosome and mtDNA markers' diversity have been largely analysed with respect to the associated paternal and maternal inheritance patterns. Through its involvement in sex determination, the Y chromosome is paternally transmitted by necessity, whereas mtDNA is maternally transmitted because it is provided by the mother’s egg cell. Where vital statistics are available, there is an effective means of investigating this sex-specific transmission and its relationship with genetic diversity. In this work, Y chromosome and mtDNA variability is analysed using a demographic database, the Population register of early Québec. This database, containing 712,000 marriage, birth and death certificates, encompasses the vital events and the kinship network of every individual of European ancestry who lived in the Saint Lawrence Valley before 1800. Every genealogical link has been traced back to the founders of the population. From this, maternal and paternal genetic contributions can be computed, and the effect of demographic differentials on the Y chromosome and mtDNA variability accounted for. The analysis shows that early Québec population exhibits a higher degree of population substructure (a higher “Fst”) for the paternal than for the maternal genetic contributions. Higher reproductive differentials and inter-subdivision migration rates for women explain this. Thus, we suspect that regions of Québec are more similar to one another with respect to mtDNA than they are with respect to the Y chromosome. Simulations are used to assess the impact of varying mutation rates, migration rate, and reproductive differentials on gene diversity indexes for both mtDNA and Y chromosome genes. |