Any of the biological properties of organisms that prevent interbreeding (and therefore exchange of genetic material) between members of different species that inhabit the same geographical area. These mechanisms include seasonal isolation, in which the breeding seasons of the different populations do not overlap; behavioural isolation, in which different courtship behaviour in the populations ensures that mating takes place only between members of the same species; morphological isolation, whereby physical differences between species prevent successful copulation or transfer of gametes; and gametic isolation, in which, e.g., sperm of one species is unable to survive in the reproductive tract of the other species. These are examples of premating mechanisms. Postmating mechanisms include hybrid infertility and inviability. See also hybrid zone.