1. Mutations: These are changes in the DNA sequence. They can occur spontaneously during DNA replication or be induced by environmental factors like radiation. Mutations can introduce new alleles (versions of a gene) into a population, increasing its genetic diversity.

2. Recombination: This process shuffles existing genetic material during sexual reproduction. It involves the exchange of genetic material between homologous chromosomes, resulting in new combinations of alleles. Recombination creates unique combinations of genes in offspring, leading to further genetic variation.