Genetic diversity

Genetic diversity is the total number of genetic characteristics found within a species, ranging from differences between species down to variation within the gene pool of a single species. It arises through mutation, which introduces new genetic material; gene flow, which transfers alleles between populations through migration; natural selection, which favors beneficial variants; and genetic drift, which randomly shifts allele frequencies, especially in small populations. Populations with more genetic variation have a better chance that some individuals carry traits suited to changing conditions, which raises their odds of survival and reproduction and therefore affects whether a species persists or goes extinct. Ecologists measure it through gene diversity, the proportion of polymorphic loci, heterozygosity, the fraction of heterozygous individuals, the number of alleles per locus, and nucleotide diversity assessed with molecular markers such as single nucleotide polymorphisms and mitochondrial DNA. Diversity within a species and diversity among species are interdependent, both contributing to the stability of ecosystems.