1. Genetic Drift: This is the random change in allele frequencies due to chance events, especially prevalent in small populations.
* Founder Effect: When a small group of individuals breaks off from a larger population and establishes a new colony, the new population may have a different allele frequency than the original population due to the limited gene pool.
* Bottleneck Effect: When a population experiences a drastic reduction in size due to a sudden event (like a natural disaster), the surviving individuals may not represent the original population's allele frequencies, leading to a shift in the gene pool.
2. Gene Flow: This involves the transfer of genetic material (alleles) between populations.
* Migration: Individuals move between populations, introducing new alleles or changing existing allele frequencies. This can lead to increased genetic diversity within a population.
* Interbreeding: Individuals from different populations mate, mixing their genes and influencing allele frequencies in both populations.
3. Natural Selection: This is the process where organisms with traits better suited to their environment are more likely to survive and reproduce, passing on those advantageous traits to their offspring.
* Directional Selection: When an extreme phenotype is favored, the allele frequency shifts towards that extreme.
* Stabilizing Selection: When intermediate phenotypes are favored, the allele frequency shifts towards the middle range, reducing variation.
* Disruptive Selection: When both extreme phenotypes are favored, the allele frequency shifts towards the extremes, potentially leading to the development of new species.
It's important to note that these mechanisms often work together, and their relative influence can vary depending on the specific population and environment.
