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#51
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rw wrote in message ...
While there's been a long history of debate about the definition (the "species problem" in biology), few if any serious biologists would deny that species are objective, concrete phenomena. This greatly constrains the possible definitions of "species." There is a spectrum of opinion. Debate and opinion, yet the definition is concrete and objective? That's a non-sequiter for me. On the far right, so to speak, are people like Jon who insist on the most rigid and absolute definiton Yep, I'm a Lumper with a capital L. This leads to absurdities, like the lions and tigers example. No more absurd than saying a chihuahua is the same species as a great dane. As I understand it, it takes a good specialist to be able to correctly identify a lion skeleton from a tiger skeleton. Surface coloration and a little different hair growth is hardly ground for speciation -- else we get back to my human and dog examples. I'd be glad to declare them subspecies -- like cutts are to rainbows, but I see no concrete scientific reason to say they are true species. The truth is in the middle. Species are "real," but pinning them down with a simple definition is hard. Ahh, but we have concrete and objective definitions, don't we? Fortunately, the definition of "species" isn't left to armchair taxonomists. As Darwin wrote to Joseph Hooker: "How painfully true is your remark that no one has hardly the right to examine the question of species who has not minutely described many." Ahh yes, we must uphold the high priesthood of rationalism, the ivory tower scientists. Us laity just can't grasp the reasoning it takes to distinguish species. We should just blindy follow and believe our priests, and if we did the world would be a much better place. Everything they say is true -- how dare we question it. If we do, they'll just laugh and call our ideas absurd, or tell us not to try to be armchair priests. Jon. |
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Jonathan Cook wrote (about lions and tigers):
I'd be glad to declare them subspecies -- like cutts are to rainbows, but I see no concrete scientific reason to say they are true species. Your case would be stronger if cutts and rainbows weren't themselves true species g The truth is in the middle. Species are "real," but pinning them down with a simple definition is hard. Ahh, but we have concrete and objective definitions, don't we? Yes, but not necessarily simple ones. It's no more than a preconceived notion (based vaguely perhaps on a common catch-all illustrative simplification previously used in junior-high science classes) that the definition of species has to be one that is simply stated and intuitively obvious. I've had lots of lengthy discussions with folks over the concept of "species" (or, to refer to another current thread here, on the pros and cons of hatchery policies in the PNW), only to have the other person say at some point, "oh, well, you know, I don't believe in evolution," as though one could have an opinion worth listening to about either subject without at least a basic understanding of evolution. Fortunately, the definition of "species" isn't left to armchair taxonomists. As Darwin wrote to Joseph Hooker: "How painfully true is your remark that no one has hardly the right to examine the question of species who has not minutely described many." Ahh yes, we must uphold the high priesthood of rationalism, the ivory tower scientists. Us laity just can't grasp the reasoning it takes to distinguish species. We should just blindy follow and believe our priests, and if we did the world would be a much better place. Everything they say is true -- how dare we question it. If we do, they'll just laugh and call our ideas absurd, or tell us not to try to be armchair priests. This article by Ernst Mayr is very useful reading (and may be where Steve found his references to "armchair taxonomists" and Darwin's correspondence with Hooker): http://members.aol.com/darwinpage/mayrspecies.htm JR |
#53
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![]() "Jonathan Cook" wrote in message m... "Wolfgang" wrote in message ... [Willi wrote:] With your definition, some of the choices that need to be made include: Actually, those are the exact choices I'm trying to take _out_ of the definition. I think the fundamental problem with the definition of species is that pesky little definite article, "the". Various definitions are extremely useful to more or less worthless depending on circumstance. Plants......you forgot about plants. How about an apple trunk grafted onto pear rootstock and later augmented with plum and cherry branches? (It's doable.....they're all Rosaceae and graft relatively easily.) Sorry, you'd have to come up with a better example. Grafting has nothing to do with reproduction. Can apple tree pollen fertilize pear tree blossoms? I don't know much about plants, but I doubt it. Doctors have experimented with pig organs in humans, but that doesn't make us the same species. (although certain individuals might make us think so :-) Well, I wasn't so much trying to come up with an example as provide an obviously absurd end point on a spectrum. Though, actually, with a bit of thought one should be able to see that it really isn't as absurd as it might appear at first glance. "Can apple pollen fertilize pear tree blossoms?" I doubt it too. However I'm not certain. There are a couple of things that make the question interesting. For one thing, both apples and pears have long been the objects of careful selection. Importantly, this selection is, by and large, NOT the sort of selective breeding generally conceeded to mirror natural selection and which, not so incidentally, played an important role the evolution of Darwin's theories. The thousands of popular varieties of apples (and, to a lesser extent, pears) developed over the centuries are mostly a result of selecting a particular fruit and then grafting the stem it grew on to a larger supportive structure.....vegetative reproduction, as opposed to genetic recombination via sex. It is a well known (and mostly true) maxim that if you plant seeds from your favorite apple you end up with a tree that produces mostly crab apples, or something very similar. The same is, of course, true for the other popular fruits in the Rose family. So, what does the prototypical pear look like? Well, despite thousand of years of selection, the similarities between apples and pears are still readily apparent. I'd guess that it looks a lot like the prototypical apple. Could two distinct (if closely related) species of grass cross-breed and produce corn? Hm.......nah, probably not. As far as single-celled organisms at the varying complexity levels go, I don't know enough to comment. Varying levels of complexity? Well, a paramecium is certainly anatomically more complex than a cyanobacterium....um, at the level of the limits of light microscopy, anyway....but it's a mistake to think that complexity on that level necessarily corresponds in a linear fashion to the scale of DNA. Species are a fiction. They can be very useful fictions, but the uses to which they are put are not always noble or even justifiable. I think _that's_ something I can agree with. Good. I'd much rather someone agree with the point while rejecting an illustrative example than vice versa. ![]() Wolfgang |
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![]() Jonathan Cook wrote: "Wolfgang" wrote in message ... [Willi wrote:] With your definition, some of the choices that need to be made include: Actually, those are the exact choices I'm trying to take _out_ of the definition. You may be trying but I don't think you'll succeed. I think I understand where you're coming from because that's how I used to look at it. But, IMO, the over simplification of using the criteria of "breed and produce fertile offspring" just opens up a different set of ambiguities. It's not as clear and concise a definition as it seems on the surface. If you accept man's intervention to define what breeding and fertile offspring means (which I assume you do - if you don't I can also make the other side of the argument) you are left with two choices: 1. To decide how much and what kind of intervention is "allowed" or 2. Accept that the definition of species will keep changing as man's technology develops. This, IMO, will lead to some VERY strange conclusions in the future. Willi |
#55
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We had a biologist from ODFG give a dog and pony show on the Fish in the
Deschutes. He said there were two populations of Rainbows. Both the same species of rainbow. One went to sea and one stayed in the river. The only way thy could tell them apart was analyzing the layers in the otoliths ( ear bones ). If the fish had been to sea it had a higer ratio of Strontium to Calcium. That's looking pretty close. "Bob Weinberger" wrote in message ... "Willi" wrote in message ... That site points to research indicating they can breed and produce fertile offspring. Sounds like a single species to me. (All other "scientific" reasons for declaring a new species are, IMO, grounded only in the scientist's desire for recognition and/or career advancement ;-) Question for you West coast guys. Do Redside Rainbows and Steelhead share any watersheds? If so do they interbreed? Willi The Deschutes is famous for both Redsides and Steelhead. To my knowledge, they are genetically indistinguishable. Some Steelhead fingerlings never go to sea and become resident Redsides and some Redsides go to sea and become Steelhead. Several other rivers in the vicinity have the same situation. The reason some rainbows exhibit anadromy, while others in the same system do not, is a mystery to fish biologists. The Steelhead in the coastal streams are derived from a different strain of rainbow than the Redsides of the interior streams. In most coastal streams virtually all the rainbows become Steelhead. The resident fish in these streams are cutthroat, though some of the cuttthroat also exhibit a degree of anadromy - going to the near shore salt for periods of 3-6mos. and returning as Searun Cutts of 13-18". Inch for inch they are better fighters than steelhead. -- Bob Weinberger La, Grande, OR place a dot between bobs and stuff and remove invalid to send email |
#56
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#57
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JR wrote:
No, seriously, I mean real evidence. You seem to draw all sorts of conclusions from talks with "a biologist" or "the guy at the hatchery." Listen asshole, I'm not a lawyer, and I don't have any legal evidence. Chas remove fly fish to reply http://home.comcast.net/~chas.wade/w...ome.html-.html San Juan Pictures at: http://home.comcast.net/~chasepike/wsb/index.html |
#59
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![]() "Wolfgang" wrote in message ... Plants......you forgot about plants. How about an apple trunk grafted onto pear rootstock and later augmented with plum and cherry branches? (It's doable.....they're all Rosaceae and graft relatively easily.) Interesting. "Relatively easily." "Doable." So you've grafted plum and cherry branches sucessfully onto an apple trunk, have you? What were the varieties pray tell? Dave |
#60
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![]() "David Snedeker" wrote in message ... "Wolfgang" wrote in message ... Plants......you forgot about plants. How about an apple trunk grafted onto pear rootstock and later augmented with plum and cherry branches? (It's doable.....they're all Rosaceae and graft relatively easily.) Interesting. Isn't it? "Relatively easily." Yep. "Doable." Yep. So you've grafted plum and cherry branches sucessfully onto an apple trunk, have you? Nope. What were the varieties pray tell? My uncle and his cousin both grafted various members of the Rosaceae onto one another. I have no idea what varieties they used. As they were both of peasant stock with something less than a high school education, neither spoke any English on arriving in the U.S., and both spent the better part of their lives doing manual labor during the daylight hours and drinking themselves into oblivion in the evenings, I suspect neither of them ever bothered to learn what varieties they were either. What's more, they probably didn't know a great deal about current events and I'm certain they couldn't pass themselves off as authorities on suitable substrates for oil based paints. Uncle Art DID have a velvet collar on a coat he owned back in the 50s, though. Wolfgang |
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