What determines genetic variation within a species and between species?
The amount of genetic variation between 2 species is determined by how long ago they last shared a common ancestor. The age of a species determines how much genetic variation can be found within it. New species are often formed by a small population, sometimes only a few individuals, and it is thought that a single pregnant female can potentially form a new species. In the beginning, therefore, genetic diversity is low as much of the genetic diversity found within the old species is lost during speciation. Therefore, if we were to examine the DNA of a species and find that most individuals within any given population and most populations have similar alleles at most loci, that is a sure sign that this species is relatively young in age. The same method can be used to determine the age of populations within a species. Scientists have found that there is more genetic variation among living Africans than there are between all other peoples on earth. That means if we pick two Africans from
