Environment couples selection and heritability

In Soay sheep, strong selection on birthweight occurs when heritability is lowest, limiting evolutionary response.

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Study species?

Soay sheep on Hirta.

Focal trait?

Birthweight.

Key claim?

Environment couples selection and heritability.

Why limits evolution?

Strong selection when genetic variance is low.

Model approach?

Random-regression animal model.

Environment metric?

Neonatal mortality-defined year quality.

Neonatal mortality share?

Substantial fraction of total mortality.

Selection across years?

Positive but highly variable differentials.

Maternal genetic variance?

Varies with environmental quality.

Takeaway?

Variable environments can stall adaptive evolution.