Walid Mawass

Walid Mawass

he/him

Evolutionary geneticist studying how population history shapes genetic variation and trait architecture — from adaptation in wild populations to prediction in human complex-trait genetics.

Evolutionary predictability in human populations

Preindustrial French-Canadian populations left behind genealogical records of unusual completeness — millions of linked individual records spanning many generations. That makes them one of the few systems in which the response of a human life-history trait to natural selection can be reconstructed directly rather than inferred from a snapshot.

I used them to test the basic prediction of quantitative genetics: a heritable trait under consistent directional selection should respond in a predictable way. It does not.

What the records show

Genotype-by-environment interaction modulates the rate of change. For reproductive timing, the genetic basis of the trait interacts with a shifting environment, so the realized rate of microevolution varies over time even where selection and heritability appear stable.

Replicate populations diverge. Where the trait is demonstrably heritable and selection is consistent and unbiased in direction, replicate populations still reached contrasting evolutionary outcomes. Consistent inputs did not produce consistent results.

The pedigree itself is a source of error. These genealogies were assembled for genealogical and demographic purposes, not for quantitative genetic inference, and their depth and completeness vary. I assessed how sensitive heritability and additive variance estimates are to that variation and to model specification — a methodological constraint that applies equally to long-term studies of wild populations.

Approach

Linear mixed-effects and Bayesian models, variance partitioning to isolate additive genetic variance from environmental variation in longitudinal cohorts, and pedigree-based quantitative genetics applied at a scale of millions of records.

Why it matters

Evolutionary forecasting — for conservation, for public health, for anticipating responses to environmental change — generally rests on estimates of selection and heritability. This work bounds how far that inference can be pushed in structured, environmentally variable populations, and it does so with data in which the answer can actually be checked.

  • Mawass, Mayer & Milot, Genotype-by-environment interactions modulate the rate of microevolution in reproductive timing in humans, Evolution (2022)
  • Mawass & Milot, Assessing the impact of pedigree attributes on the validity of quantitative genetic parameter estimates, Journal of Evolutionary Biology (2025)
  • Mawass & Milot, Contrasting evolutionary outcomes in a human life history trait which is heritable and under consistent unbiased directional selection (preprint)