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.
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in heritable traits of a population over time. Charles Darwin popularised the term natural selection; he compared it with artificial selection (selective breeding). Variation exists within all populations of organisms.