Biology subjects

Milot, E.

Publications and source records attributed to Milot, E..

2 recordsLinked to original sources

bioRxiv2022

Assessing the impact of pedigree quality on the validity of quantitative genetic parameterestimates

Investigating the evolutionary dynamics of complex traits in nature requires the accurate assessment of their genetic architecture. Using a quantitative genetic (QG) modeling approach (e.g., animal model), relatedness information from a pedigree combined with phenotypic measurements can be used to infer the amount of additive genetic variance in traits. However, pedigree information from natural systems is not perfect and might contain errors or be of low quality. Published sensitivity analyses revealed a limited impact of expected error rates on parameter estimates. However, natural systems will differ in many respects (e.g., mating system, data availability, pedigree structure), thus it can be inappropriate to generalize outcomes from one system to another. French-Canadian (FC) genealogies are extensive and deep-rooted (up to 9 generations in this study) making them ideal to study how the quality and properties (e.g., errors, completeness) of pedigrees affect QG estimates. We conducted simulation analyses to infer the reliability of QG estimates using FC pedigrees and how it is impacted by genealogical errors and variation in pedigree structure. Broadly, results show that pedigree size and depth are important determinants of precision but not of accuracy. While the mean genealogical entropy (based on missing links) seems to be a good indicator of accuracy. Including a shared familial component into the simulations led to on average a 46% overestimation of the additive genetic variance. This has crucial implications for evolutionary studies aiming to estimate QG parameters given that many traits of interest, such as life history, exhibit important non-genetic sources of variation.

evolutionary biology↗

bioRxiv2021

The effective family size of immigrant founders predicts their long-term demographic outcome: from Quebec settlers to their 20th-century descendants

Human evolution involves population splits, size fluctuations, founder effects, and admixture. Population history reconstruction based on genetic diversity data routinely relies on simple demographic models while projecting the past. No specific demographic assumptions are needed to understand the genetic structure of the founder population of Quebec. Because genealogy and genetics are intimately related, we used descending genealogies of this population to pursue the fate of its founder lineages. Maternal and paternal lines reflect the transmission of mtDNA and the Y-chromosome, respectively. We followed their transmission in real-time, from the 17th century down to its 20th-century population. We counted the number of married children of immigrants (i.e., their effective family size, EFS), estimated the proportion of successful immigrants in terms of their survival ratio, and assessed net growth rates and extinction. Likewise, we evaluated the same parameters for their Quebec-born descendants. The survival ratio of the first immigrants was the highest and declined over time in association with the decreasing immigrants EFS. Parents with high EFS left plentiful married progeny, putting EFS as the most important variable determining the parental demographic success throughout time for generations ahead. The 17th and 18th-century immigrants bear the most remarkable demographic and genetic impact on the 20th-century population of Quebec. Lessons learned from Quebec genealogies can teach us about the consequences of founder effects and migrations through real peoples history. The effective family size of immigrant founders predicts their long-term demographic outcome.

evolutionary biology↗