Microevolution

Microevolution is the occurrence of small-scale changes in allele frequencies in a population, over a few generations, also known as change at or below the species level.

These changes may be due to several processes: mutation, natural selection, gene flow, genetic drift and nonrandom mating.

Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution; for example, bacterial strains that have antibiotic resistance.

Microevolution can be contrasted with macroevolution; which is the occurrence of large-scale changes in gene frequencies, in a population, over a geological time period (i.e. consisting of lots of microevolution). The difference is largely one of approach. Microevolution is reductionist, but macroevolution is holistic. Each approach offers different insights into evolution.