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Author Topic:   Is convergent evolution evidence against common descent?
zephyr
Member (Idle past 4540 days)
Posts: 821
From: FOB Taji, Iraq
Joined: 04-22-2003


Message 241 of 311 (215687)
06-09-2005 4:04 PM
Reply to: Message 208 by randman
06-08-2005 11:19 AM


Re: Inconsistent?
quote:
130 and 173 seem to me more significant.
That's like the difference between 3 years and 4 years. Significant? Yes. It confirms what has always been suspected by anyone with a lick of sense, that mutation rates cannot be expected to have remained constant across all species for millions of generations. They are constant enough to give a general idea of time frames for divergence, but nobody ever claimed they could tell us the day and hour when two major taxa last interbred. The possibility of a +/-20% variation in rates of mutation - for diverse species in massively different environments - is not denied by biologists and would not invalidate the whole field of research.
Oh, hi. I'm Jeff. Been lurking in the thread and finally got near the recent stuff so I'm trying to contribute. There you have it.

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randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 242 of 311 (215700)
06-09-2005 4:36 PM
Reply to: Message 239 by MangyTiger
06-09-2005 3:49 PM


Re: Inconsistent?
Mangy, I haven't had any time to post today, but saw your comment and realized a quick reply would suffice.
The types of changes you listed are no more than the types of changes we see sometimes even with species that can interbreed, once you take out the reproduction. The difference is that there are these fairly small differences over a wide group of animals.
I am not saying Marsupials do not have some distinctiveness in other areas, but that there are great similarities, more so in many ways, between Marsupial and Placental pairs than with many other species within their own order.
In general, I think everyone on this thread ought to look at pics of the physical appearance from the outside, their bone structure and anatomy. I don't know how to post pics, but it's a lot clearer when you actually see the astonishing depth of similarities in the pairs.

This message is a reply to:
 Message 239 by MangyTiger, posted 06-09-2005 3:49 PM MangyTiger has not replied

Replies to this message:
 Message 243 by zephyr, posted 06-09-2005 5:04 PM randman has replied

zephyr
Member (Idle past 4540 days)
Posts: 821
From: FOB Taji, Iraq
Joined: 04-22-2003


Message 243 of 311 (215706)
06-09-2005 5:04 PM
Reply to: Message 242 by randman
06-09-2005 4:36 PM


Re: Inconsistent?
quote:
saw your comment and realized a quick reply would suffice.
It did not at all suffice. Do you have examples of interbreeding species where one has a fenestrated palate and one doesn't? Any examples of *any* of the listed differences which are also found between known, interbreeding species? You can't just handwave these facts away. You need to at least demonstrate that you understand them, and you haven't even done that yet.

This message is a reply to:
 Message 242 by randman, posted 06-09-2005 4:36 PM randman has replied

Replies to this message:
 Message 245 by randman, posted 06-09-2005 6:40 PM zephyr has replied

Chiroptera
Inactive Member


Message 244 of 311 (215708)
06-09-2005 5:14 PM


Deja vu all over again
You know, this is reminding me of when Robert Byers was arguing that each marsupial independently microevolved from placental mammals after the flood.

randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 245 of 311 (215721)
06-09-2005 6:40 PM
Reply to: Message 243 by zephyr
06-09-2005 5:04 PM


Re: Inconsistent?
No, you need to reread the thread. I provided an example of a huge range of difference within 2 species that could breed, heck 2 that are so different that they have been classified by some as in different sub-families, the pseudo-orca and the bottlenose dolphin.
Have you even looked at the differences, visually looked at them, for a "fenestrated palate"? Do you even know what "fenestrated palate" means?
The wholphin comes from parents not with a slight difference in number of teeth or some such, as there is between the thylacine and wolf, but one has twice the number of teeth and the other twice the size of teeth. The difference in body size alone is massive. I would argue that separating some of the obvious differences in manner of reproduction and associated anatomy, that a marsupial and placental pair is anatomically more similar than some species within the same family, and even sometimes 2 species that can interbreed.
So get off your high horse and read through the thread!
Look at the following link for a pic of a fenestrated palate, which not all marsupials have, but most do. It's not a major morphological difference compared with the similarities in marsupial/placental pairs.
Here is a opossum palate.
ADW: Not Found
And here is a dog palate.
ADW: Not Found
This message has been edited by randman, 06-09-2005 06:43 PM
This message has been edited by randman, 06-09-2005 06:46 PM
Here is a side by side view of the thylacine and the wolf. Note the article, imo, exagerrates the differences. They exist, but so do differences within the same family, and larger differences in fact.
http://www.naturalworlds.org/..._thylacine_skulls_nojava.htm
This message has been edited by randman, 06-09-2005 06:56 PM

This message is a reply to:
 Message 243 by zephyr, posted 06-09-2005 5:04 PM zephyr has replied

Replies to this message:
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zephyr
Member (Idle past 4540 days)
Posts: 821
From: FOB Taji, Iraq
Joined: 04-22-2003


Message 246 of 311 (215725)
06-09-2005 7:04 PM
Reply to: Message 245 by randman
06-09-2005 6:40 PM


Re: Inconsistent?
I have read the thread, and I find it amazing that you have so much time to write and so little time to learn, and so much capacity for repetitious argument. As long-winded and tiresome as your posts can be, I have read all of them. Your assumption is thus incorrect.
The wholphin is indeed a fascinating thing. I don't claim to understand the mechanisms involved.
Regardless:
You didn't answer any of my questions, and the charge of condescension would be better aimed at yourself. I at least can acknowledge when I'm out of my depth, whereas you routinely turn your nose up at the work of your superiors.
Thanks for the pic links, but I don't see their purpose here. FYI, if I hadn't already known what a fenestrated palate was, I could have figured it out. Also, having read the entire thylacine page linked earlier in the thread, I am aware that they are a good example of a marsupial with a highly fenestrated palate while a wolf is not. Your last post does nothing to support your point (if you have one) but it makes me wonder if dogs and possums can interbreed. Now that would be a funny thing....

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 247 of 311 (215726)
06-09-2005 7:08 PM
Reply to: Message 245 by randman
06-09-2005 6:40 PM


Different Differences.
First; I am not an anatomist so I am only offering an opinion. We have one post that comes from an anatomist Message 239 which gives an idea of what kind of differences there are. These have always made it possible to separate the marsupials from the placentals. Those who understand what they are doing do NOT see the two types as the same.
What you are over looking is that convergence happens on those features which are subject to the converging selection pressures. The different sorts of features which you have had pointed out to you before. The thylacine and wolf skulls look similar to your untrained eye because it is the gross shape that is subject to the common environmental pressures.
However, the details are not subject to the same pressure and/or are not something which can be changed easily. These are those which are (partially) listed in 239.
It is the contrast between features that HAVE to be selected to fit a specific ecological niche and those which do not that helps show weather something is common descent or is convergence. You have not yet discussed this in any realistic way.
It is my uninformed conjecture that ALL the marsupials can be grouped based on the features other than the reproductive system. That they are specifically NOT placental in many ways which have nothing to do with the placenta.
Now, after that is done, we are starting to get the protein and genetic data available. And, proponderantly, it agrees that the marsupials are NOT closely related to the placentals but ARE more closely related to each other. This supports the convergence.
Now, you suggest that the common features that are ascribed to common descent could also be convergence.
randman writes:
If convergency can produce identical ear design in the sense of the 3 ear bones, it could darn well explain anything, and that's something you don't want to admit.
Convergency can, it appears, produce some very similar outcomes when starting with similar intial points. You have a point with the specific examples you pick. However, what convergency does that is different from common descent is that it preserves non-selected differences. The cases are, for the most part, differentiated by features which you both ignore and are not particullary aware of.
It is the preservation of the differences which separates convergency from common descent.
Now when all that is done then we look at the genetic evidence and, while you disagreed that they would, they match the previously postulated relationships and places where convergency and common descent are used as the explanations. With common descent we expect a closer genetic match and we expect the match to be closer when the over all morphology is closer too (since, in general, the close morphology (but not always) means a more recent divergence (Chimp and human for example). With convergence we do NOT expect the genetic match to align and it does not.
You keep jumping on a few individuals points and do not answere the overall pattern at all.

This message is a reply to:
 Message 245 by randman, posted 06-09-2005 6:40 PM randman has replied

Replies to this message:
 Message 248 by randman, posted 06-09-2005 7:20 PM NosyNed has replied
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randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 248 of 311 (215731)
06-09-2005 7:20 PM
Reply to: Message 247 by NosyNed
06-09-2005 7:08 PM


Re: Different Differences.
Ned, I never disagree that there would be genetic evidence to support the marsupial classification, but I said I suspected there would be a case that showed otherwise, and only did so at your request to make a prediction. Thus far, the evidence shown is far too scant to determine if there is an exception to the general pattern.
But I also always maintained that while this is indeed useful, it does not negate the point in the OP. It provides more data, and that is useful.
As far as the degree of similarity between marsupial and placental pairs, I once again suggest a side by side comparison with creatures that you say are genetically closer in relationship with.
For example, let's look at the differences in human anatomy, giraffes, and a mole, and then compare side by side comparisons of marsupial/placental pairs, and it's quite obvious which are anatomically more similar.
That does not negate some similarities considered "tell-tale" signs, but even with that, you see a greater apparent similarity in anatomy at times produced theoritically via convergent evolution than you do otherwise.
If you know how to post pics, why not just show the pics? It's obvious I am telling the truth.
Look at the dog, wolf and thyacine skulls, and compare those to a human skull, and tell me which is more anatomically similar. Do the same with all of the bones.
I am not making something up.
Sure, you can link some fairly small items like the fenestrated palate in, but that does not negate my point in any respect. The similarities between the pairs, via convergent evolution presumably, are greater than the similarities of many placental species.
To deny that, again and again, as you guys are doing is to deny the facts, and imo, is dishonest.
It is good that the data on the genetics is getting posted, and I have fully agreed that it does not show a similarity genetically that matches the physical similarity, but you guys cannot seem to admit the basic truth of the incredible level of similarity between the marsupial/placental pairs.

This message is a reply to:
 Message 247 by NosyNed, posted 06-09-2005 7:08 PM NosyNed has replied

Replies to this message:
 Message 251 by NosyNed, posted 06-09-2005 7:51 PM randman has replied

randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 249 of 311 (215732)
06-09-2005 7:33 PM
Reply to: Message 247 by NosyNed
06-09-2005 7:08 PM


Re: Different Differences.
Ned and zephyr, look at the following pics in the links.
thylacine skull
http://www.naturalworlds.org/...ne/skull/skull_life_size.htm
wolf skull, (does not seem to be wolf as close as some to the thycaline but it will work for this).
World of the Wolf - wolf skull
OK, now let's look at a human skull.
http://iregt1.iai.fzk.de/KISMET/medimg/CThead_2a.jpg
Are you guys really claiming the human skull is closer anatomically to the wolf than to the thylacine is to the wolf here?
How about the skull of a dolphin?
Access denied
Now, let's look at a pic of a false killer whale skull.
Access denied
Look closely at the differences between the false killer whale and the dolphin. Are they greater or less than one would find in the skulls of Marsupial/Placental pairs?
Sure, since marsupials have a few tell-tale traits, one can use those to identify them, but it's obvious that the similar traits produced by convergency are often more and greater than the similar triats within even the same Order of other mammals.
This message has been edited by randman, 06-09-2005 07:35 PM
This message has been edited by randman, 06-09-2005 07:36 PM

This message is a reply to:
 Message 247 by NosyNed, posted 06-09-2005 7:08 PM NosyNed has replied

Replies to this message:
 Message 250 by NosyNed, posted 06-09-2005 7:45 PM randman has not replied

NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 250 of 311 (215734)
06-09-2005 7:45 PM
Reply to: Message 249 by randman
06-09-2005 7:33 PM


Re: Different Differences.
You and I can look at skull pictures all we want. It requires a real anatomist to comment on the deep differences or not. It was their detailed examination of the differences that separated these major branches of the mammals.
I already suggested that you are being fooled by over all similarities, just what might be expected from convergence. I think they look very similar too. But one still shows the features of marsupials and shares those basic features with them and one does not.
Not being an anatomist, I can't be sure, but I suspect that you will find that much of the differences and similarities are similar to those between a doughnut and a coffee cup. They look very different but to a topologist are the same thing. My suggestion is that many of the similarities between wolf and human will be like the relationship between a doughnut and a coffee cup. The basic material doesn't change but the relative sizes and shapes of the bits do.
You are again not recognizing that there MUST be two different kinds of differences and similarities. It isn't the degree of differences it is the form of the differences.
Now, for a moment let's put that aside. Let's say that the similarities that we say are common descent are convergence just as we say they are between marsupials and placentals.
Why then is there a difference in the relationship of the genetics that matchs the, you say, wrong attribution to common descent?

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 Message 249 by randman, posted 06-09-2005 7:33 PM randman has not replied

NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 251 of 311 (215735)
06-09-2005 7:51 PM
Reply to: Message 248 by randman
06-09-2005 7:20 PM


Re: Different Differences.
I am not making something up.
Sure, you can link some fairly small items like the fenestrated palate in, but that does not negate my point in any respect. The similarities between the pairs, via convergent evolution presumably, are greater than the similarities of many placental species.
To deny that, again and again, as you guys are doing is to deny the facts, and imo, is dishonest.
I know you are not making anything up. You say "small items" but there are many of them. Most or all of them the kind of thing that are expected when convergence is the explanation. The small items add up to a different pattern that is discernable by anatomists.
There was no reason for them to clump these groups this way other than by such specfic differences which you don't recognize as important because you are not an anatomist but are willing to look at gross anatomy.
We have never denied the gross anatomical similarities and differences that you want to point to. What we are trying to point out is that isn't what separates placentals from marsupials and that it is NOT JUST the reproductive anatomy and process that is the deep differences.
You are brushing off the genetic evidence that has been presented. There hasn't been, I agree, a lot yet. However, let's have your comment on what has been presented. We claim the genetics divide the groups like the detailed morphology does. In general I say it does. If that does hold up what do you have to say then?

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Replies to this message:
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randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 252 of 311 (215737)
06-09-2005 8:00 PM
Reply to: Message 251 by NosyNed
06-09-2005 7:51 PM


Re: Different Differences.
Most or all of them the kind of thing that are expected when convergence is the explanation. The small items add up to a different pattern that is discernable by anatomists.
But pattern and similarity are 2 different things, which is something I think you are being unnecessarily reticient about admitting. Let's say identical twins are separated at birth and one raised in the South and one raised in the Bronx. If you want to say the pattern of speech shows which one is which, that's fine, but they are still more similar than they are with other people from the South or the Bronx.
I know that's not a perfect example, but it serves my point. The similarities are greater via convergence than the similarities between, say a whale and a human.
In fact, you talk about details versus just the overall shape, but there are very large differences in details between a human skull and say, a mole or a giraffe or between many placentals.
What you are pointing out are some specific differences that form a pattern, which evolutionists have decided places the Marsupials closer to each other than their counterparts, but that does not negate the fact of great similarity in the pairs.
On the genetics, at this point, if you cannot read and understand that every single post I have fully admitted the data, then no, I am not going to repeat myself on it.
I'll just say this. I have been honest about the data thus far. I don't think everyone arguing in your camp on this thread has been likewise honest about the data.
WK has been good, and offerred real data, and shown more of a willingness to discuss matters instead of overstate them, and there may be others, but a lot of this thread has consisted of evolutionists making overstatements and erroneous claims, imo.
This message has been edited by randman, 06-09-2005 08:02 PM

This message is a reply to:
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randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 253 of 311 (215741)
06-09-2005 8:11 PM
Reply to: Message 251 by NosyNed
06-09-2005 7:51 PM


Re: Different Differences.
Ned, it is interesting to see what genetic research says, especially if similar form corresponds to similar gene sequences. Thus far, the answer seems to be no, but WK pointed out there is on-going research into this issue.
As far as whether Marsupials evolved via a mutual common ancestor, or the creationist someone linked to is correct, on kinds, really it does not matter for this thread.
The issue gets more complicated, imo, when examining things like the presumed reptile/mammal evolution that is so highly touted. I submit that perhaps:
1. We cannot say if many of the similarities arose via convergence from creatures that did not have the same traits (even when there are fossils of species earlier that had the same trait). Convergent evolution is shown to be, if you accept that Marsupials had a common ancestor, that nearly identical traits can evolve independently.
2. The "gaps" in the data, both in the time-frames between the fossils and the lack of DNA, are highly problematic for assuming mutual ancestry, in many cases.
I am not claiming to be an expert, but evolutionists have often and frequently shown skulls to illustrate the suppossed evolution of mammals from reptiles. I think an objective person ought to consider that such similarity in form can emerge via convergent evolution, assuming that is correct.

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 Message 251 by NosyNed, posted 06-09-2005 7:51 PM NosyNed has not replied

randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 254 of 311 (215745)
06-09-2005 8:41 PM
Reply to: Message 226 by mark24
06-09-2005 4:34 AM


Re: Inconsistent?
Mark, I will try to respond more later, but what do you make of the following comment in an encyclopedia article?
It should however be noted that these molecular results are still highly controversial mainly because they are not reflected by morphological data and thus not accepted by many systematists.
Global Industry Market Sizing - NationMaster
Your suggestion is that the morphological data and molecular data match, but that appears not to be the case.
Why is that?

This message is a reply to:
 Message 226 by mark24, posted 06-09-2005 4:34 AM mark24 has replied

Replies to this message:
 Message 261 by mark24, posted 06-10-2005 3:16 AM randman has replied

randman 
Suspended Member (Idle past 4889 days)
Posts: 6367
Joined: 05-26-2005


Message 255 of 311 (215747)
06-09-2005 8:46 PM


to all on the thread
For many years their place within the Marsupials was hotly debated, some workers regarding it as an offshoot of the Diprotodontia (the order to which most living marsupials belong), others noting similarities to a variety of other creatures, and making suggestions that, in hindsight, appear bizarre. A 1989 review of the early literature, slightly paraphrased, states:
When Stirling (1888) initially was unable to find the epipubic bones in Marsupial Moles, speculation was rife: the Marsupial Mole was a monotreme, it was the link between monotremes and marsupials, it had it closest affinities with the (placental) golden moles, it was convergent with edentates, it was a polyprotodont diprotodont, and so on. [1] (http://www.ea.gov.au/...f/fauna/foa/pubs/volume1b/23-ind.pdf)
The mystery was not helped by the complete silence of the fossil record. On the basis that marsupial moles have some characteristics in common with almost all other marsupials, they were eventually classified as an entirely separate order: the Notoryctemorphia. Molecular level analysis in the early 1980s showed that the marsupial moles are not closely related to any of the living marsupials, and that they appear to have followed a separate line of development for a very long time, at least 50 million years.
Global Industry Market Sizing - NationMaster
The molecular data given here does not seem to match what we have come up with in our scant review. Maybe the Marsupial mole is worth looking into a bit more?
Note also that prior to the molecular data, there were anatomists that speculated:
it had it closest affinities with the (placental) golden moles
This message has been edited by randman, 06-09-2005 08:48 PM

Replies to this message:
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