How does genetic variation within a population contribute to evolution?

Genetic variation within a population contributes to evolution by providing the raw material for natural selection.

Genetic variation is the diversity in the genetic makeup among individuals within a population. It is the foundation upon which evolution acts. Without genetic variation, a population cannot evolve in response to changing environmental variables and may face an increased risk of extinction.

Genetic variation arises from mutations, which are changes in the DNA sequence of an organism's genome. These mutations can occur spontaneously or be induced by environmental factors such as radiation or chemicals. While many mutations are neutral or harmful, some can confer an advantage to the organism, making it more likely to survive and reproduce. This is the basis of natural selection, the primary mechanism of evolution.

When a population is exposed to a new environment or a change in the existing environment, the individuals with the genetic traits that best suit the new conditions are more likely to survive and reproduce. This process, known as 'survival of the fittest', leads to an increase in the frequency of the advantageous traits in the population over time. As a result, the population evolves.

Genetic variation also results from genetic recombination, which occurs during sexual reproduction. During meiosis, the chromosomes from each parent can exchange segments, leading to offspring with unique combinations of traits. This increases the diversity of traits within a population, providing more opportunities for natural selection to act.

In addition, genetic variation can be introduced into a population through gene flow, which is the transfer of genes from one population to another. This can occur through migration or interbreeding between populations. Gene flow can introduce new traits into a population, increasing its genetic diversity and potential for evolution.

In conclusion, genetic variation within a population is crucial for evolution. It provides the raw material for natural selection, allowing populations to adapt to changing environments and evolve over time. Without genetic variation, populations would lack the flexibility needed to survive in a changing world.