Here's why:
* Mutations are changes in the DNA sequence. These changes can be small (a single nucleotide change) or large (a whole chromosome deletion or duplication).
* Mutations introduce new alleles (versions of genes) into a population. This is the primary source of genetic variation.
* Natural selection acts on existing variation. It favors individuals with traits that make them better suited to their environment, allowing those individuals to reproduce more successfully and pass on their advantageous genes.
* Over time, this process of mutation and natural selection can lead to significant changes in the genetic makeup of a population, resulting in the evolution of new species.
Other factors that contribute to genetic variability:
* Gene flow: The movement of genes between populations can introduce new alleles.
* Sexual reproduction: Recombination of genes during meiosis creates new combinations of alleles, increasing variation.
However, mutation is the ultimate source of new genetic material. Without mutation, there would be no new variations for natural selection to act upon, and evolution would stagnate.
