Population genetics explores how genetic variation changes in populations over time through key evolutionary mechanisms.
Hardy-Weinberg equilibrium serves as a theoretical baseline for understanding population genetics, stating that allele frequencies remain constant unless disturbed by evolutionary forces. This principle requires five conditions: random mating, no natural selection, no mutation, no gene flow, and large population size. When populations deviate from these conditions, evolution occurs. The Hardy-Weinberg calculator helps determine expected genotype frequencies in idealized populations.
Genetic drift represents random changes in allele frequencies, particularly impacting small populations. The Bottleneck effect occurs when population size drastically reduces, while the Founder effect happens when a small group establishes a new population, both leading to reduced genetic diversity. Gene flow introduces new alleles through migration between populations, potentially increasing genetic variation. Natural selection acts on heritable traits affecting survival and reproduction, driving adaptive evolution over time. Mutations provide the raw material for evolution by creating new alleles, though most are neutral or harmful. Understanding these mechanisms helps explain how species change over time and adapt to their environments. The negative effects of genetic drift in small populations include loss of genetic variation, increased homozygosity, and reduced adaptive potential. Notable examples of mutation in evolution include antibiotic resistance in bacteria and pesticide resistance in insects, demonstrating how random genetic changes can lead to adaptive advantages under specific environmental pressures. These evolutionary forces work together, shaping biodiversity patterns we observe today. For instance, the founder effect genetic drift explains unique traits in isolated populations, like the high frequency of Ellis-van Creveld syndrome among the Pennsylvania Amish. Natural selection examples include the evolution of camouflage in moths during the Industrial Revolution and the development of longer beaks in Galápagos finches during droughts, illustrating how environmental pressures drive evolutionary change.