Answer: Environmental variance
Step-by-step explanation:
The portion or part of the phenotype variance which is due to the differences in the environments in which the individuals in a population has been exposed.
These type variation is caused by factors Which are found in the environment.
examples of such factors are
1. diet
2. Temprature e.t.c
just like the example cited in the case in East Africa milk purchased is less due to their lactose tolerance this is an example of an environmental variance.