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Posted by SNYDER on January 09, 1999 at 10:42:40:
In Reply to: Species is only Taxonomic level that is "real" posted by Troy Hibbitts on December 30, 1998 at 18:35:56:
: Systemacists hold that "species" is the only level of taxonomy that is "real" - all others (Kingdom, Phylum, etc, etc) are categories of convenience. Over recent years, there has been a movement to make the higher levels of taxonomy more closely reflect evolutionary history (i.e. "real"ity), but this has met with great resistance, as it would do away with the old categories (Kingdom, Phylum, etc) and add to the list of names (one name for each "clade", or evolutionary grouping of organisms . . . and names would include ancestors, etc . . . mammals would therefore become "the first common ancestor of living marsupials, monotremes, and placentals).
: Anyway, species, IN CONCEPT, represent real groups of organisms . . . organisms with their own evolutionary trajectories, history, and fate . . . i.e they are separate from all other organisms (reproductively isolated, either by biology, behavior, allopatry, etc). It is simply failure of humans, through inadequate data or inadequate analysis of data, that causes species to be misidentified, etc. But nature "knows" what a species is . . . each species "knows" what a species is . . . you know that you are a human, right? My dog knows that she is a dog and not a cat . . . etc, etc.
: Troy
I can't agree that "nature" or anybody else knows or can know what a species is in all cases. Sure, dogs don't (can't) breed with cats, but consider two populations of the same species, seperated by geography. They begin to diverge genetically. We'll all agree that when they can't produce fertile offspring- they're seperate species. But they may be isolated for thousands of years before they reach that point. They may be morphologically quite distinct, enough so that even a taxonomic "lumper" considers them good species. Then climate changes, interbreeding occurs and... oops they ain't seperate species after all. Were they ever? Nature is fluid. The only way taxonomy can reflect reality is to recognize this and change to reflect new evidence. Considering the flux in taxonomic opinion this wouldn't seem to be a problem. And sure, the species concept works most of the time- nobody confuses a mouse with an alligator. But there is no way to say for certain if the Texas Alligator Lizard population in Texas is a distinct species or the same species as the population in Southern Mexico. It is a matter of opinion and convenience. Now if you can predict whether they WILL become genetically isolated, true species...I wanna talk to ya about next weeks lottery numbers.
D.E. Snyder
TEX_ALL_LIZ@Hotmail.com
