>The most common definition is reproductive compatibility but that is so complex As one example, the ability to breed is not always transitive.[1] - A can b

>The most common definition is reproductive compatibility but that is so complex As one example, the ability to breed is not always transitive.[1] - A can breed with B - B can breed with C - A can't breed with C Are A, B, C the same species? [1] https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species