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Author | Topic: Convergent Evolution - Reasonable conclusion? or convenient excuse? | ||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Wounded King,
I don't see that this has much bearing on my previous comments though in terms of genetic support for the nested hierarchy. There's another element to consider. From the first abstract: Convergent sequence evolution between echolocating bats and dolphins - PubMed
quote: If the changes result in sensitivity to certain frequencies used in echolocation, it could be a matter of resonance fitting: the amino acid substitutions changing the resonance response. For the same response in other species, the same substitutions would result in the same resonance fitting, while different substitutions would not. Selection for the resonance response would result in selection for the same sequences. Enjoy. Edited by RAZD, : /qs we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Wounded King, it's just a thought.
I'm not sure how that is another element to consider, since it is the whole point of both articles. They both posit convergent protein sequence evolution of Prestin as a result of selective pressures associated with echolocation. It's the issue of resonance, like a vibrating string ...
quote: Presumably the hair vibrates in response to sound. This is how sound is normally sensed, yes? Different mutations would cause different resonance frequencies (length, folding, weight distribution of the protein and change the hair), so selection for specific frequencies would result in selection for specific amino acid sequences.
But as I have been pointing out, protein sequences and amino acid substitutions are not really genetic data in and of themselves. Selection for the resonance response only selects for the same amino acid sequences not the same DNA sequences. While this selection will affect the DNA sequences to some extent it still allows a lot more variability than at the amino acid level. I would not be surprised if you could compare any convergent species and find some similarities at this level (rather than the genetic level).
For Bob's argument to make any sense the nested hierarchy really needs to fall apart at the genetic level, it is no good him just choosing an arbitrary phenotypic level and then saying, look at these supposedly convergent traits they blow a major hole in the darwinian nested hierarchy approach. I would think there would have to be a failure of any other nested hierarchy. If evidence of some kind of intelligent design "reuse" of features is being sought, then there should be multiple examples of features "borrowed" from multiple other species, to the point where no consistent nested hierarchy could be derived. Enjoy. we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi BobTHJ, and welcome to the fray.
Just a small point or two.
The overall evidence for a nested hierarchy is not high - the many cases of 'convergent evolution' demonstrate this. Do you know how many different species are currently living? This list is less than 1% of the NEW species recently added to the catalog of life: Number of Earth's species known to scientists rises to 1.9 million | Wildlife | The Guardian
quote: And evidently we still don't know all of them. While there are only 100 instances listed in the wiki article, and I don't call 100/1.9X10^6 = 0.005% a significant problem.
What does have a lot of evidence is the conclusion that creatures with similar morphological features will share similar genes. Which is why, when you look at the details for animals that appear similar at the gross level, they show convergent evolution from different branches of life. One from your - actual wiki's - list is the thylacine and wolf:
quote: If you look closely you will see differences in each picture that are due to different hereditary ancestry. These differences are why biologists know that this is a case of convergent evolution. We had a thread here a while ago that went into detail on the actual anatomical differences between these two organisms, and this showed that the basic detail level (number and type of teeth for instance) the characteristics of the thylacine were closer to the other marsupials than to the placental mammal wolf and that the grey wolf were closer to other placental mammals than to the marsupial thylacine. Unfortunately the last time I checked for it, it appeared that the photos were no longer showing (the links were not working). Curiously, the nested hierarchies of animals based on their morphological traits put these two animals in different clades, the grey wolf with the placental mammals and the thylacine with the marsupials, because of the morphological details. We see similar detail differences in sugar-gliders and flying squirrels (also on the list):
When we look at the details once again, we see that the sugar-glider is clearly a marsupial and the flying squirrel is clearly a placental mammal, and these detailed differences are what the nested hierarchies are based on. The same holds for the other organisms on this list.
However, as I mentioned in my previous post, where do you draw the line? Not all traits fit neatly into a nested hierarchy. Where you draw the line is based on the preponderance of evidence at the detail level. Interestingly, the same kind of nested hierarchy can be formed from genetic information, and if evolution is not the correct explanation, then there is no reason for a genetic hierarchy to match the one developed on the morphological details. Fascinatingly, these two versions of nested hierarchies agree to phenomenal levels of comparison with very little error.
However, this conclusion does not support common ancestry and more than it supports baraminology. Amusingly you don't show how "it supports baraminology" but just make an unfounded assertion. Enjoy
I counted the list by changing the bullet to numbers by global substitution. The thylacine is #3 and the sugar-glider is #9. Many items on this list are only specific traits (see opposum opposable thumb) rather than whole organisms. List of examples of convergent evolution - Wikipedia
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi again BobTHJ,
Cases of common morphology without common genetics does not make common design an unreasonable conclusion. Silly Design Institute: Let's discuss BOTH sides of the Design Controversy... ... at issue is the purpose of design that we can infer from the evidence. Enjoy. we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi again BobTHJ,
I haven't looked, but it is probably safe to assume that the vast majority of these species are the result of recent variation (we may define 'recent' differently, but suffice it to say that they have very close relatives) so it seems your figure should be substantially less. I also doubt that the wikipedia article is comprehensive in nature as I've seen mentions of several hundred or more cases of convergency. As a result it is likely the percentage is substantially higher than .005%. Except that (1a) all the convergent evolution examples include living species AND some fossil bits of evidence PLUS (1b) some of the examples are only specific traits (such as opposable thumbs) rather than the appearance of the whole organisms, as in the example of the flying squirrel and sugar glider, WHILE (2) "The number of species on the planet that have been documented by scientists has risen to 1.9 million" is only currently living species. Therefore a proper comparison would be much lower than 0.005% (take out the fossil examples, take out the single feature examples).
As I stated in another thread - I suspect the phylogenetic tree to be a 95%+ accurate categorization of living organisms (ontology only - no common descent implied) - with these non-conforming cases composing the other <5%. Just stating this for the record so everyone knows where I stand. Of course, and you also must realize that opinion is completely impotent at altering reality in any way. You are free to hold whatever opinion you wish, but if you are ignoring reality and evidence that contradicts your opinion, the only one you are fooling is yourself.
Yes - and that seems to be what happens. Organisms are placed into the phylogenetic tree at the location where they show the most similarity to the surrounding organisms. This reflects a good ontology model - though it does lead to some inconsistency since some organisms classed in different clades still share similarities not shared by other closely classed organisms. Perhaps you would like to offer some evidence to show what you mean? Are you talking about lost traits? Nobody is claiming that the nested hierarchies are necessarily true, just that they are the best known explanation of life as we know it, based on the information available. Curiously, these nested hierarchies can be developed (a) in the traditional morphological detailed study method that has been used in biology since Linnaeus, and (b) based on genetic information. With design there is no reason for these two trees to be the same. With evolution the two trees must be the same, and they are. Enjoy. we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Taq,
Fish and squid share the same exact environment, and their eyes serve the same exact function. Their eyes are significantly different in their design. Remember what you said earlier? Better still, compare the octopus eye to the nautilus eye, same environment, similar behavior, both use tentacles to capture prey, and need eyes to see the prey.
Enjoy. Edited by RAZD, : images addedded we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined:
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Hi BobTHJ, thanks.
Of course. You disagree with my opinion that the phylogenetic tree correctly models similarity (both morphological and genetic) to a degree higher than 95%? I didn't think many people would fight me on that assumption. Amusingly, that is not the opinion that flies against scientific evidence. This issue is the 5% where you think there is wiggle room for your opinion to differ from science.
Sure, echolocating in bats and dolphins. They are not classed together in the phylogenetic tree (nor should they be if you want the most accurate ontological model possible) yet share a similarity not shared by other closely grouped organisms. Except that this is not an example of where the 5% of the phylogenetic can be wrong. The phylogeny is based on hereditary traits rather than developed traits. The "most accurate ontological model" would be based on inherited traits, and it would recognize that traits that appear similar because of independent development do not interfere with the phylogeny. Homologies and analogies - Understanding Evolution
quote: The echolocation in bats and dolphins are developed analogous features, not inherited homologous features, and thus this does not interfere with the phylogenetic tree based on hereditary development.
A high degree of correlation between genomes and morpholocial features fits well with a design hypothesis. Just because darwinian evolution fails without that correlation doesn't mean it is the more reasonable conclusion. A question for you is how you can distinguish your design hypothesis from the evolutionary hypothesis, not just telling yourself that the evidence shows design.
Message 52: quote:If we failed to find significant similarity between life forms it would evidence against a common designer. Message 53quote:Of course - if organisms lacked significant similarity to each other then you would have evidence against common design. For example, if organisms didn't share a similar cell structure but instead most used a basic anatomical unit that was different from other organisms this would be evidence against common design. Or if organisms didn't all use DNA/RNA but instead each used its own method of storing data - that would be evidence against common design. Both are fairly reasonable conclusions - they both fit the data. What I take issue with on these claims are:
By this means you avoid confrontation with evidence that invalidates belief, you just brush it away by telling yourself "oh it's consistent with (some kind of undefined generic) design hypothesis so it's okay" ... but it's no different than saying "god-did-it" and it doesn't predict any answers that would not be provided by evolution. In a nutshell, you have failed to show how convergent evolution is due to design rather than evolution, or that evolution fails to explain convergence. To maintain the thread topic here, I have continued my reply on the thread Silly Design Institute: Let's discuss BOTH sides of the Design Controversy..., Message 164. Enjoy. ps - with special thanks to Berkeley University for providing such an excellent resource: Evolution 101Evolution 101 - Understanding Evolution Edited by RAZD, : clrty we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi again BobTHJ,
To clarify my comments on the phylogenetic tree (referenced by Taq in Message 58, Catholic Scientist in Message 62, and Percy in Message 66, and RAZD in Message 67): The ontology is a useful tool to group organisms on similarities. Those similarities may occur at the genetic level, the morphological level, the behavioral level, etc. Since the inception of phylogentics similarities determine how organisms are grouped. Based on hereditary traits, rather than arbitrary grouping because it looks nice. These homologous traits are similar because of descent from common ancestors, and they can be traced back to a common ancestor that had the same traits.
My point is that this leads to cases (such as bat/dolphin echolocation) where organisms that share one or more similarities at some level are not closely grouped. My statement is not made to validate or invalidate common ancestry (the conclusion many draw) - I am simply referring to the ontological model. And your point fails because these are analogous traits arrived at independently, rather than inherited through a common ancestor. When you trace the hereditary lineages back in time, these traits disappear from the ancestral traits before a common ancestor is reached.
Dissimilarity in a single feature is not significant. Note that cephalopods and vertebrates still share the same cellular structure, the same DNA structure, etc. There is a host of similarities - it reeks of common design. Curiously all life "still share the same cellular structure, the same DNA structure, etc." so you have not stated anything other than a mundane truth that makes you similar to a tree. Yeah, that reeks. Amusingly this little equivocation means that your bat/dolphin echolocation example is completely useless in making your point, because you have revealed yourself as intellectually dishonest (whether consciously or not) by applying a double standard:
One little similarity in a part of one feature is highly significant, even though the rest of the features show dissimilarities. One little dissimilarity in one feature is not significant at all, because the rest of the features show similarities. Riiiight. Don't pay attention to the man behind the curtain .... Enjoy. Edited by RAZD, : clr we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Mr Jack and Wounded Knee (and Percy makes three),
What does "tree length" mean? The tree length is the number of individual changes required to form the tree, this is, each time we swap a single letter to another to make the tree the tree length increases by one. The most parsimonious tree(s) for a given set of data is the one with the lowest tree length - in other words, the one that applies the same mutation the least number of times. Doesn't Percy's original tree only have a length of 3? I'm curious why the original tree was not reproduced by this analysis. Certainly it should be the most parsimonious solution, yes? Enjoy. we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Thanks Wounded King, Mr. Jack, Percy
Adding in the ancestral sequence as an outgroup still doesn't give me Percy's tree exactly, but it does produce a tree with a length of 14. And Mr. Jack had one with a tree length of 12 (Message 81). I had wondered if making an outgroup would help, and if adding a lot more 'a's to the lineages (to more completely model the relatively small proportion of the genome that mutates).
Mr. Jack Message 90: The outgroup is important because it helps the program determine which states are later mutations and which states were there originally. The second reason is that Percy's example happens to have multiple mutations at the same site, specifically the first mutation on the left branch is then overwritten by the second mutation on the leftmost branch (AAAAAAA->AAAAABA->AAAAAGA). Which would be a rare occurrence in a real world example, so we can avoid this in making future models (or use a longer genome and a random generator for location and change).
Percy Message 91: I can pretty easily write a program to generate genomes for the PARS program to analyze, but I need feedback on a few things. This list is for producing a final population through normal reproductive descent:
What would be a good genome size in nucleotides for the PARS program to analyze? What would be a good number of generations? What would be a good number of offspring produced per organism per generation? What would be a good final population size? For the designer case I'll start with a certain number of individuals, then take them through enough generations to give the same size final population as in the evolution case. I could use Bob's feedback on this. How many original individuals should I start with? How many nucleotide sequences should they have in common? Given that this thread is about convergent evolution, perhaps we need to start with two different genomes and run the mutations/generations, with come mechanism to select for a specific output? For the designer model we would also need to see some predictions of what the design would cause:
Perhaps work backwards from the final results of the evolution model, so we have the same end but different hypothetical beginnings. Enjoy. we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi ramoss, good question, hope you get an answer.
And why would that be evidence against 'darwinism'. Because he said so. Of course this would be 'darwinism' according to his interpretation, and not necessarily evolution as used in science.
Please define 'significant quantity'. A lot more than we have seen:
quote: BobTHJ has not really answered my previous post on this issue, but has gone off on other tangents. And I would say that the (documented) extremely LOW incidence of convergent evolution examples is evidence against the IDologist claims of "reuse of design" - especially when there are numerous examples of opportunities for "reuse of design" to have been used that have been missed. Enjoy. we are limited in our ability to understand
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RAZD Member (Idle past 1431 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi barbara, and welcome to the fray.
I wouldn't use natural selection to describe the vast differences across species especially when it lists the same type of animal that is classified as such based almost identical features in appearance and then state they are unrelated. Not sure I understand you here, could you expand your argument some, and provide reference to an example from my post?
This list does not make any sense whatsoever and if it is suppose to be presented as the facts then good luck on convincing anyone of this crap. Well that's one way to deal with not understanding the issue. It's just a list of instances where some similarities have evolved in different species, some of them with a high degree of similar appearance. Again, I'm not sure what your issue is, so you may want to expand on this as well. Enjoy.
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