Board Thread:General Discussion/@comment-27745396-20170905185708/@comment-294840-20170926214611

On how the dividing line between species gets blurry I HAVE studied biology and I would like to give you a well known example dealing with gulls around the Arctic Circle. Group A's territory overlaps with group b it can interbreed with group b. Group b's territory goes on to overlap with group c group b and c can interbreed. And so on by the time we come to group g, which can interbreed with group f by the way, we have come back to where we have begun and the territory of group g overlaps with group a. Since group g is connected to group a by a bunch of different groups wich can all interbreed you would assume it could interbreed with group a wouldn't you? NOPE. Group A and Group G are genetically incompatible even though their genetic middlemen still exist today.

This is what makes it so tricky to divide the lines between species.