In biology, races are distinct genetically divergent populations within the same species with relatively small morphological and genetic differences. The populations can be described as ecological races if they arise from adaptation to different local habitats or geographic races when they are geographically isolated. If sufficiently different, two or more races can be identified as subspecies, which is an official biological taxonomy unit subordinate to species. If not, they are denoted as races, which means that a formal rank should not be given to the group, or taxonomists are unsure whether or not a formal rank should be given. According to Ernst W. Mayr, "a subspecies is a geographic race that is sufficiently different taxonomically to be worthy of a separate name" [1][1] Examples of race include: