Question

The mathematical equation for heritability is H²= V_G / V_P. ( or H² = V_G / (V_G + V_E). Explain the meaning of the heritability of a trait in a population. Explain the conditions that exist in a population when H² = 0. Explain the conditions that exist in a population when    H² = 1. For most traits in real populations is heritability usually at either of these extremes? Explain

Answer 1

In this equation H2 denotes heritability and it is based on ratio between genotypic variance (VG) and phenotypic variance (VP) phenotypic variance further depends on genetic makeup and environmental factors hence both will be taken into consideration.

When H2=0

All variation is due to environment because genetic factor values will nullify each other

H2= VG/VG+VE

H2= 0/0+VE

hence

H2=0

And when H2=1

Here all the variation is due to genes if environmental variation is 0 then

H2 = VG/VG+VE

H2= VG/VG+0

Hence

H2= 1

In real traits under normal conditions populations will never be at such extremes because every organism after taking birth will start interacting with its environment and variations due to environment plays a major role in heritability of traits.

Similarly the genetic makeup of every organism is prone to errors and mutations which causes variation in heritable genes hence both the factors are important to the heritability of genes.