Impact of fertility transmission and other sociodemographic factors on reproductive success and coalescent trees.
Summary            Fertility transmission (FT) is a phenomenon with a cultural and/or genetic basis, whereby a positive correlation exists between the number of offspring of an individual and that of his/her parents. Theoretical studies using a haploid individual-based model have shown that FT increases the variance and intergenerational correlation in reproductive success and results in an imbalance in the coalescent tree of sampled genes. This phenomenon has been documented in several demographic studies conducted on the correlation in fertility between generations, or through the reconstruction of the genealogical trees of mitochondrial DNA sequences. However, as mtDNA is a single locus, potentially subject to other forces (e.g. natural selection), it is of interest to extend the theory of FT to nuclear loci. We show that because random mating between individuals leads to a mixing of their fertility profiles, FT in these cases will have less influence on the variance and intergenerational correlation of reproductive success. This, in turn, results in less impact on the shape of the coalescent trees. Nevertheless, in the presence of FT, high heterogeneity in reproductive success and homogamy for family size will increase the imbalance in the coalescent tree. Thus, FT should be easier to detect when occurring in conjunction with these other factors. We also show the utility of analysing different kinds of loci (X-linked, Y-linked, mitochondrial and autosomal) to assess whether FT is matrilineal, patrilineal or biparental. Finally, we demonstrate that the shape of the coalescent tree depends upon population size, in contrast to the classical Kingman's model.
Eco-Anthropologie et Ethnobiologie, Univ Paris Diderot, Sorbonne Paris Cité, Paris, France.
Jean-Tristan
JT
Brandenburg
Frédéric
F
Austerlitz
Bruno
B
Toupance
D002648:Child; D003198:Computer Simulation; D004272:DNA, Mitochondrial / Q000235:genetics; D003710:Demography; D005260:Female; D005298:Fertility / Q000235:genetics*; D006801:Humans; D008297:Male; D008957:Models, Genetic; D010375:Pedigree; D012098:Reproduction / Q000235:genetics*; D012641:Selection, Genetic; D012959:Socioeconomic Factors
D004272:DNA, Mitochondrial