Mechanisms of Genetic Change - EVOLUTION

Microevolution (evolution on a small-scale) refers to the changes in allele frequencies within a single population. Allele frequencies in a population may change due to four fundamental forces of evolution: Natural Selection, Genetic Drift, Mutations and Gene Flow. Mutations are the ultimate source of new alleles in a gene pool.
Two of the most relevant mechanisms of evolutionary change are: Natural Selection and Genetic Drift. One of the main controversial issues in population genetics is concerned with the relative importance of both mechanisms in determining evolutionary changes. Natural selection usually predominates in large populations whereas genetic drift does so in small ones.
subdividerLearn
1.- Natural Selection
Natural Selection leads to an evolutionary change when some individuals with certain traits in a population have a higher survival and reproductive rate than others and pass on these inheritable genetic features to their offspring. Evolution acts through natural selection whereby reproductive and genetic qualities that prove advantageous to survival prevail into future generations. The cumulative effects of natural selection process have giving rise to populations that have evolved to succeed in specific environments. Natural selection operates by differential reproductive success (fitness) of individuals.
The Darwin’s Finches diagram illustrates the way the finch has adapted to take advantage of feeding in different ecological niches: