This work is based on demographical, genealogical and genetic data.
The focus is on the the Saguenay Lac St jean (SLSJ) in the Quebec Province of Canada. In this population, high frequencies of some inherited disorders can be found and we have revealed that this increase in gene frequency is explained by socio-demographic behaviour and their cultural transmision.
Thanks to the BALSAC project, a hudge set of genealogies and demographic data are available for the eastern part of Quebec Province.
In the SLSJ, I have demonstrated that there is a cultural transmission of the reproductive success from one generation to the next. This cultural phenomenon increases the stochastic change in gene frequency (drift) and explains the high frequency of some inherited disorders in this population (Austerlitz, Heyer, PNAS, 1998).
In order to better understand the impact of the cultural transmission of reproductive success or fertility inheritance, I have (with other collegues) worked on the theoretical aspects of this question. Using a colaescent approach, we have shown that the transmission of reproductive success changes the shape of the genalogical trees and that this phenomenon can be measured by an imbalance index. Using mitochondrial data we have demontsrated the existence of this transmission of reproductive success in several non-farmers populations around the world.
We pursue this work in a diploïd model.
This work follows my first research on the Valserine Valley in France where there is also a high frequency of some inherited disorder. It was shown that the population could be divided into two groups of families : stable families with greater local reproductive success and migrants with lower local reproductive success. This social structure, transmitted from one generation to the next, led to the maintenance of a genetic disorder at increased frequency despite a high level of gene inflow from surrounding populations (26% of in-migrant by generation). An allele carried by an individual belonging to the core has a selective advantage of 0.2 because of this social structure.
Life history analyses :
We have worked on
the impact of family care on the survival of the children and its implication for the evolution of survival after reproduction of women.
inbreeding depression and fertility.