"Species" is an arbitrary designation. Maybe arbitrary isn't exactly the right term, but it's a label which says 'right now, this is different from that' , wher

"Species" is an arbitrary designation. Maybe arbitrary isn't exactly the right term, but it's a label which says 'right now, this is different from that' , whereas over evolutionary time actual organisms will interact and intermingle in ways which (as seen in these comments!) aren't adequately captured by the categories into which we divide them.