Walmart assistant managers average $45,000 a year, which is right on target for the national average salary, according to Glassdoor salary data. If you factor in bonuses and additional compensation, the average pay increases to $48, 311 a year.
Natural selection can only work on existing variation within a population. Such variations arise by mutation, a change in some part of the genetic code for a trait. Mutations arise by chance and without foresight for the potential advantage or disadvantage of the mutation.
Basically, this is simple effect of breeding. Natural selection is the effect natural variation has on survival of a species. Consider the variational model to produce 10 children from one parent set, where the fingers are ranging from very short, to longer and very long.