1. Variation:
- Within a population, there is natural genetic variation among individuals. This variation can be attributed to mutations, genetic recombination, and other sources of genetic diversity.
2. Differential Survival and Reproduction:
- The environment poses challenges and selective pressures on individuals within the population. Those individuals with traits that are better suited to the environment have a higher chance of surviving, reproducing, and passing on their genes to the next generation.
3. Survival of the Fittest:
- Individuals with advantageous traits, known as adaptations, have a greater likelihood of surviving and producing offspring. The process of natural selection favors the survival and reproductive success of these adapted individuals, while individuals with less favorable traits are less likely to pass on their genes.
4. Accumulation of Favorable Traits:
- Over generations, beneficial traits that enhance survival and reproductive success become more common within the population. This leads to a gradual accumulation of favorable adaptations.
5. Adaptation:
- As natural selection continues to act on populations, beneficial traits become increasingly prevalent, allowing populations to become better adapted to their specific environments.
6. Changes in Allele Frequencies:
- Natural selection directly influences the frequencies of different alleles within a population. Alleles associated with advantageous traits increase in frequency, while alleles for less favorable traits decrease in frequency or may be eliminated altogether.
7. Changes in Gene Pool:
- The selective pressures imposed by the environment cause shifts in the overall gene pool of the population. The accumulated adaptations become part of the population's genetic makeup, altering its genetic composition.
8. Population Divergence:
- Over time, natural selection can lead to significant divergence between populations that experience different selective pressures. Different populations may become adapted to their unique environmental conditions, leading to the formation of new species through the process of speciation.
9. Evolution:
- Through natural selection, advantageous adaptations become increasingly common in the population, altering its heritable characteristics and driving evolutionary change over generations.
In summary, natural selection operates by favoring individuals with beneficial traits, leading to the accumulation of adaptations that enhance survival and reproduction. This process results in changes in allele frequencies, genetic composition, and eventually, the evolution of populations and the formation of new species over time.