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 driving force for boom and bust cycles and for the evolution of fungicide resistance in plant pathogens. Selection can occur on genes (increasing and decreasing the frequencies of specific alleles) or on genotypes (increasing and decreasing the frequencies of specific clones).