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Post by leilani on Aug 18, 2009 22:39:11 GMT -10
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Post by leilani on Aug 18, 2009 22:35:07 GMT -10
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Post by leilani on Aug 18, 2009 22:26:21 GMT -10
I have noticed this in N. rafflesiana uppers at times.
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Post by leilani on Aug 4, 2009 0:06:43 GMT -10
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Post by leilani on Aug 3, 2009 23:57:52 GMT -10
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Post by leilani on Aug 3, 2009 23:47:05 GMT -10
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Post by leilani on Jul 29, 2009 23:03:26 GMT -10
I'd like to spin off a new thread out of this discussion ......
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Post by leilani on Jul 29, 2009 23:00:19 GMT -10
In another thread leeb wrote .....
The primary subject of this thread is “Will this new information bring clarity to Nepenthes taxonomy?”
I’ll start this off with a few thoughts .....
Traditionally Nepenthes classification has been based almost completely on morphological features. This classification was the answer to the very basic and practical need to impose organization upon our garden (world). Based on discernible morphological features a naturalist or nurseryman could recognize and differentiate one group of plants from another. With a particularly tricky distinction an eye-piece might be required but most often differentiation was made with the naked eye.
Now, of course, Nepenthes taxonomy has become more sophisticated than the simple field observations and eye-piece of the past but, fundamentally, it remains a very practical cataloging of differentiable visible features. For the purposes of this thread lets call this “Local Taxonomy”.
With the growing acceptance of Darwinian thinking, taxonomy began to bear a new burden. No longer just a reasonable and practical catalog of differentiating characteristics, taxonomy was now expected to also reflect the underlying and unifying relationships of an organism’s evolutionary history.
Soon, as leeb says, through genetic analysis we may open wide new doors to our better understanding of the evolution and familial histories of the various Nepenthes species. Our technologies have expanded our potentials for differentiation far beyond those available to the taxonomist of the last millennium and, if we so choose, we can differentiate species into a far larger than practicable number. Although “local” visually differentiable features are still recognized are the most practical of defining characteristics they are no longer necessarily the most fundamental. Let’s call this activity “Analytical Taxonomy”.
Secondary question might include ....
Can “Local” and “Analytical” taxonomy be reconciled into one system without sacrificing either the scientific integrity of the classification or its practical utility?
What if we find that the visual characteristics we have been using for classification (considered so fundamental for so long) do not reflect, in the manner we have assumed them to, the underlying genetic histories of those species. Will large portions of Nepenthes taxonomy need to be thrown in the trash?
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Post by leilani on Jul 28, 2009 22:06:29 GMT -10
The simple stuff .... This is a fascinating and well constructed explanation. It only takes one, they can do without food for a good period of time and "floating tortoises" are more common than you would think. ;D I really love the last part .... Let me say that this is perfectly plausible. One of the few advantages we seem to have in trying to unravel evolution is "plenty of time". If an argument seems implausible in a local time frame it may still work if given enough time. If required then, it is well within the rules to call up a tsunami, hurricane or continental migration. Just adjust the metric. I am not suggesting that I doubt any of this but am just a bit amused by the convenience of it. Thanks for your response on the Margulis question. Its true, all the examples are restricted to simple micro-organisms but, then again, size and complexity follow. It would think that the vast majority of genetic material imported would be 'junk'. On the other hand, it seems to have worked to monumental effect when it has worked. Mitochondria and chloroplasts being the most outstanding examples. This does sound implausible. But if we conveniently adjust the metric ..... it seems quite plausible.
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Post by leilani on Jul 28, 2009 15:35:32 GMT -10
Hi leeb, I was aware of these effects but what I was really getting at, and the reason for my hesitation in asking, is how you feel about the work of Lynn Margulis? I realize that the notion of micro-organism based symbiosis is difficult to apply to questions of larger life forms like Nepenthes but wonder how do you feel about the idea of 'captured' genetic material (from organelles and the like) becoming incorporated into the genetic makeup of larger ("colonial") life forms? Forgive me but since I have no credentials at stake and little to lose by being wrong I sometimes allow my speculation to stretch and even break with well accepted scientific 'facts'. This having been said, I now feel free to say the following ..... I, like everyone else, have often wondered about the carnivorous nature of Nepenthes. Just how did a plant come about developing such a radically different (secondary) method of sustaining itself? Trying to figure out most of the adaptations and evolution of Nepenthes is not much different from trying to follow the evolution of other families of plants but the origin of carnivority in this and related plants would seem, to me at least, to be a much harder to explain. There would seem to be no genetic precedent for such a revolutionary adaptation in these plants. Assuming that Nepenthes evolved from some non-carnivorous ancestor it would seem doubtful to me that it brought this potential with it. OK .... off the deep end! So radical does this adaptation seem to me that I wonder that it might not be the result of the incorporation of genetic material ( .. in some undefined process) from another life form ( .. perhaps bacterial). Has much research been done on the bacterial infauna of Nepenthes pitchers? Are there particular "families" of bacterial that are common to all Nepenthes? It seems to be generally accepted that the breaking down and consumption of captured prey is a cooperative effort with the bacterial infauna. I know this is "off the wall" but there seems to be precious few scientists willing to even speculate on the origin of this adaptation. There are a fair number of small, very specific studies of Nepenthes pitchers and how they work but little or no one willing to suggest an explanation of how such an radical adaptation might have come about in the first place. Anyway, throw your scientific integrity to the wind for a moment and tell me what do you think. I promise we won't let any scientists read it. Ohh, BTW ..... I find it a little difficult to accept the idea of "floating tortoises" having colonized all of these remote locations. Although they may float I wonder just how long can a tortoise survive at sea? And just how many tortoises must one float in order to get lucky and have a male and female arrive safely on the same remote island. Well, I guess it is no different from any of the other life forms that somehow arrived on these islands via the sea .... but it is a funny picture. ;D
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Post by leilani on Jul 27, 2009 23:49:01 GMT -10
Thanks for the clarification leeb. I want to be sure were using the same terminology. I understand this but wonder just what it is in the differing phylogenies than implies a hybridization event. From these quotes I take it that the assumption is that greater morphological disparity suggests greater age. This seems reasonable and fits well with the Darwinian model .... with selection and random genetic drift as the primary modalities of evolution. But even if we accept this does it really imply a parallel between the morphological disparity of a species and the time it has been around ( .. in other than a trivial way) or might there not also be long periods of relative stability (Gould). And, what is relative stability? Is it 1000 years or, as in the example of the Coelacanth, a couple hundred million years? __________________________________________ Ohh, how I miss the good old days when floating tortoises was an accepted form of family entertainment. ;D __________________________________________ Yes, but can we really expect these species to change according to the same timetable. With something like “genetic drift” I suppose we can calculate a certain amount of change based solely upon a time schedule of some number of years. But with “selection” this seems more problematic. Selection would seem to be opportunistic and not tied to any easily predictable schedule. Can we really expect species, even within the same family, to follow the same predictable schedule of change? I hesitate to ask but, does your understanding of evolution allow for any modalities of change beyond "selection" and "genetic drift"?
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Post by leilani on Jul 26, 2009 21:48:40 GMT -10
Welcome to the land of unrestrained speculation leeb! It's a real pleasure to have you with us. ;D I think most here have some familiarity with "Mullins and Jebb's studies". In my own case I am not sure just how much of it I understand. I have heard that this work seemed to indicated that the lowland species you mention are of "hybrid origin" but I am not sure what this means or how it is inferred by the study. Perhaps, you could enlighten me in words I would understand. How would the "hybrid" status of these species change any of the arguments regarding relative age? You say it might be and "ancient" or a "relatively recent" event. It would be tempting to suggest that it could have been some ancient "hybrid event" and the resultant heterosis in the lineage that has strengthened these populations and lead to their wide spread success as compared to "non-hybrid" species. I'm a little puzzled by your example of the tortoise. (I though "polyphyletic" was a dirty word among taxonomists and cladisticians.) Are you suggesting that Nepenthes might be polyphyletic? What exactly would this mean?
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Post by leilani on Jul 26, 2009 21:01:48 GMT -10
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Post by leilani on Jul 26, 2009 20:59:45 GMT -10
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Post by leilani on Jul 19, 2009 9:30:18 GMT -10
Hey Peat,
On the main screen (on the right-hand side) is a sideline header that reads "Quick Nepenthes References". Wikipedia is about as up to date as any list these days. Try that.
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