Comparison of Mutational Heritability across Traits

Across a range of organisms, the mutational heritability, V_M/V_E, is lower for traits associated with growth or reproduction than it is for adult morphology (Fig. WN14.4). This is the same pattern that we saw earlier in this chapter for overall heritability (see Fig. 14.19). It arises for the same reason: The environmental variance for traits associated with growth and reproduction is much higher than that for adult morphology, and so their heritability is lower. When the mutational variance is scaled relative to the trait mean, the pattern is reversed. This is consistent with the idea that mutation generates more variability for traits such as overall growth rate or reproductive success, which are likely to depend on very many genes.