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Posted by John A. on December 30, 1998 at 12:20:38:
In Reply to: Re: Lampropeltis triangulum and the definition of "species" posted by SNYDER on December 29, 1998 at 16:37:37:
I don't think any scientist (I'm not one) would argue against the species designator as being artificial. The subjectiveness of the system is based upon the fact that it came about to determine "relationships" of living things to each other. Every new discovery causes the entire structure to shift to absorb the new material. Geography and morphology help us make assumptions about relationships but inevitably physiology and reproductive compatability will determine the real extent of those relationships. When you have a species that ranges as widely as Lampropeltis triangulum the odds of finding new material to cause adjustments to the structure increases. Just my .02
: : I am not a scientist so forgive me if this is "old hat" to the the rest of you. Also forgive spelling and phrasiology, it's early A.M. This is something which has bothered me for a while now and never had a forum to address it. The subject is Lampropeltis. More specifically, L. triangulum. To me, triangulum will always be the eastern milk [L.t. triangulum]. I find it very hard to consider most of the tri-colored "milks" of SW U.S., Mexico and C. America as having subspecies relationship. Besides appearence [morphology?], behaviour and location are so divergent it casts much doubt [in my mind] on the validity of subspecific designation for many types of milksnakes. I think part of the problem is that there is no adequate definition of what a species is. Before Darwin and Wallace, species were "immutable", well defined, rigid and bearing no close relationship to any other. Through much of the time following Darwin et al, a species was best seperated by the "mule" concept. If they interbreed and produce fertile off-spring, they're sub-species. It seems to me that designator is no longer valid. A case in point being the chichlid fish of the rift lakes in Africa. Dozens if not hundreds of "species" are found in a particular lakes which are clearly evolved from one or two species. New species keep turning up in places were to seperate species were formally isolated and then brought together by human activities. These new species would formally be considered hybrids but breed true, and if kept isolated, become a "new" species.
: : I guess I'm rambling. Is there a good definition of species? Does anyone agree Lampropeltis is a mismash of seperate species and subspecies? Thanks, I fell much better know.
: "SPECIES" is an artificial concept that sometimes does not fit nature precisely. Usually it means a gene pool (a group of organisms) that is reproductively isolated. If the test is whether individuals DO interbreed, and not whether they CAN interbreed, then every isolated population is a species. If the test is CAN they interbreed, then your fish, along with lions and tigers are NOT seperate species (witness the liger). The only thing I know about snakes is that I like snake eyelid soup, so I can't answer that question. If I had to define "species" I would say "A group of organisms within which, under natural conditions, there is a flow of genes, even if this exchange is sporadic or rare."
: A favorite conundrum is a bird, Arctic Tern I believe, that is nearly circumpolar. It intergrades from one form to another all around the globe-clearly a good species. But at one point the birds do not interbreed, East with West, and were at first considered seperate species. More complete knowledge made the situation clear.
: I repeat: the concept is artificial. And variable.
: Different taxonomists, relying on morphology alone, differ in opinion as to what should constitute a species. But even with perfect knowledge to the molecular level there would not be agreement in all cases.
: D.E. Snyder
