mrh@cybvax0.UUCP (Mike Huybensz) (12/09/86)
Followups to sci.bio and talk.origins. In article <2849@bu-cs.BU.EDU> bzs@bu-cs.BU.EDU (Barry Shein) writes: > For what it's worth I believe the acid test of a new species is that > it is no longer able to breed with the original species it evolved > from. Morphological changes alone aren't sufficient (until which time > those changes prevent inter-breeding.) What you believe is irrelevant. :-) The fact is that biologists cannot decide what constitutes a species. Many will tell you that species are really fictions. But useful fictions. Different criteria are used to decide what species are in different taxa (groups of organisms). This isn't due to the fact that different workers have different opinions. It's due to the fact that no single definition is useful for all taxa. The complications arising from the diversity of organisms and the sources of that diversity make your test impractical. First, there is the temporal question: is a species today really the same species that existed X years ago? How can we test if the ancestral species has died out? What if hybridization is possible but the progeny are less fit (or even sterile)? Say hybridization can occur in the lab but doesn't in nature? Because of distance? Because of different pollinators? Because of different behavior? What about continuously interbreeding populations whose members at opposite extremes of the range can't interbreed? What about parthenogenetic organisms? Is every one of them a species? -- "People always HAVE eaten people; people always WILL eat people. You can't change human nature!" (From "The Reluctant Cannibal" on the Flanders and Swann album "At The Drop Of A Hat".) -- Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh