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.
Over time, this process can result in populations that specialize for particular ecological niches and may eventually result in the emergence of new species. In other words, natural selection is an important process (though not the only process) by which evolution takes place within a population of organisms.