1. Mutation: This is the ultimate source of new genetic variation. It's a random change in the DNA sequence of an organism. These changes can be beneficial, harmful, or neutral in their effects.
2. Gene Flow: This refers to the movement of genes between populations. It can occur when individuals migrate from one population to another, introducing new alleles into the receiving population. Gene flow can reduce differences between populations.
3. Natural Selection: This is the driving force behind adaptation. Individuals with traits that make them better suited to their environment are more likely to survive and reproduce, passing those advantageous traits on to their offspring. Over time, this process leads to populations becoming better adapted to their environment.
4. Genetic Drift: This is the random change in allele frequencies within a population, especially in small populations. It occurs due to chance events like the death of individuals carrying certain alleles or the chance survival of others. Genetic drift can lead to the loss of genetic diversity and can result in significant changes in a population's genetic makeup over time.
These four processes work together in a complex interplay to drive the evolution of life on Earth.
