Thread by @WiringTheBrain

Interesting and important findings (from 2018, but new to me!) 🐭⬇️

https://twitter.com/SergeAhmed/status/1462815455429767168

You'd expect phenotypic variance to be lower in inbred strains cuz genetic variance (Vg) = zero.

But because they are inbred (homozygous at all alleles) the ability of cellular systems to buffer noise or environmental fluctuations may be much lower

This means that the non-genetic sources of variance (here called Ve, but not necessaarily "environmental") may be much higher:

Homozygosity is BAD! (Not just cuz of specific deleterious recessive effects, but generally for the robustness of the whole system)

This has parallels in the slightly increased variance of males > females for all kinds of traits, most likely due to hemizygosity (having only one copy) of the X chromosome

Making the entire genome homozygous should have correspondingly larger effects on variance