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Author Topic:   Definition of Species
Coragyps
Member
Posts: 5399
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 61 of 450 (540859)
12-29-2009 2:47 PM
Reply to: Message 59 by herebedragons
12-29-2009 2:14 PM


Re: Speciation discussion
What I would be interested in learning more about is a mosquito that has developed a variation....

The London Underground mosquito is what you're after:
http://en.wikipedia.org/wiki/London_Underground_mosquito

Edited by Coragyps, : fix tag


This message is a reply to:
 Message 59 by herebedragons, posted 12-29-2009 2:14 PM herebedragons has not yet responded

    
RAZD
Member
Posts: 20156
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 4.1


Message 62 of 450 (540891)
12-29-2009 10:37 PM
Reply to: Message 59 by herebedragons
12-29-2009 2:14 PM


Re: Speciation discussion
Hi again herebedragons, thanks.

I also think I read somewhere that you are going through chemo? So understandable that it would take a while for you to respond.

Yes I am four years into life after getting the diagnosis, and this is my fourth time into chemotherapy. Each time a different chemical needs to be used, as the cells that survived from the last sessions are immune to the old ones. So evolution is trying to kill me ...

The main reason I joined this forum is to learn about the reasons that scientists accept evolution. I am taking it "step-by-step" and as I learn more about the facts, I am sure I will view many things differently. I am trying to have an open mind, and come to my own conclusions based on what I learn. Because much of our understanding of the fossil record is based on what we know from observation of the present, at this time, I am trying to focus on learning what we actually know from observation of the present.

Have I introduced you to what I think is the best resource on the web for learning about evolution?

http://evolution.berkeley.edu/evosite/evo101/index.shtml

This is a self-guided university level program of articles that covers all the basic topics in a clear and readable manner.

It has this article on the definition of species:

http://evolution.berkeley.edu/...101/VADefiningSpecies.shtml

It gives the "biological definition" we have seen above, and then goes on to discuss some of the problems, and has links to other definitions for further study.

and then there this one on the definition of speciation:

http://evolution.berkeley.edu/.../VBDefiningSpeciation.shtml

quote:
So we meet again: When another storm reintroduces the island flies to the mainland, they will not readily mate with the mainland flies since they’ve evolved different courtship behaviors. The few that do mate with the mainland flies, produce inviable eggs because of other genetic differences between the two populations. The lineage has split now that genes cannot flow between the populations.

We don't know whether the ring species terminal varieties would produce viable offspring or not, as this has not been mentioned in any of the literature that I have seen, but it is a possibility. One indication of this is that the hybrid zones between the different varieties are small, and this generally indicates that the hybrids are less fit than the bordering varieties, as they cannot disperse into those areas and spread the hybrid zones. If the hybrid zones shrink then genetic speciation is on the way for the varieties as well.

Thus it is possible that the eastern and western end varieties have attempted breeding but did not produce any zygotes. We don't know.

I found examples of Agapornis (Love Birds) that can hybridize across three levels of the polygenetic tree. I realize that the examples happen primarily in captivity, rather than in the wild. But it is still a bit confusing as to why after speciating three times they are still closely related enough to produce viable offspring.

This is a good time to introduce the concept of the subjectivity of how many divisions one needs to make. You will hear terms of "splitters" and "lumpers", where the "splitters" like to divide the populations up into as many species as possible (at one extreme), and the "lumpers" like to group them together into as few species as possible (at the other extreme). A Lumper would call all those varieties within one species, while a Splitter would claim they are three species that produce hybrids under some special conditions (ie captivity).

The thing to recognize is that the ability to produce hybrids does not necessarily mean that two varieties are 100% interfertile.

If normal reproduction is successful 50% of the time (for argument sake) and the hybrids are only produced in 25% of cross-variety mating, then there is a distinct difference in reproductive success. This difference can be sufficient for natural selection to select against individuals that chose to cross-mate and for individuals that chose to mate with their own variety, over time causing more and more loss of viability between the groups until full reproductive isolation occurs at the genetic level.

The other factor that can happen is that the hybrid is less able to mate with others, and perhaps has only a 30% success rate independent of mates chosen. This too will lead to selection against the hybrids and an accumulation of mutations that make them less and less viable.

Another example is the greenish warblers. My thinking about this situation goes something like this ... Let's call the original population species 'A'. And each variation around the ring is represented by '1' with the eastern group being '+' and the western group being '-' (to indicate variation is going in different directions).

Excellent thinking. I was thinking of a table like approach myself:

P.trochiloidesnitidusviridanusludlowitrochiloidesobscuratusplumbeitarsus
nitidusviableunknunknunknunknunkn
viridanusunknviablehybridunknunknnone
ludlowiunknhybridviablehybridunknunkn
trochiloidesunknunknhybridviablehybridunkn
obscuratusunknunknunknhybridviablehybrid
plumbeitarsusunknnoneunknunknhybridviable

Now a Lumper could claim that they are all one species, while a splitter could claim that there are four distinct species - P.nitidus, P.viridanus, P.trochiloides and P.plumbeitarsus, where the varieties ludlowi and obscuratus are hybrids (making the hybrid zones larger and more dominant).

Given that isolation between obscuratus and plumbeitarsus has occurred due to habitat destruction, we could say that there are three species - P.nitidus, P.trochiloides, and P.plumbeitarsus, where P.trochiloides has four varieties, viridanus, ludlowi, trochiloides and obscuratus.

Or these are potential species (we only know that viridanus and plumbeitarsus don't breed while having the opportunity to do so, the other groups are formed more by geological separation than by opportunity to breed). Geological separation can result in genetic isolation if mutations are selected that make such interbreeding non-viable when opportunity is provided (as in the doves in captivity). We don't know at this time if this is so.

Thus the definitions of species and speciation are problematical in some certain special instances. What we may be seeing in these situations is incipient speciation, speciation that is not fully realized at this time, but which is underway.

Because much of our understanding of the fossil record is based on what we know from observation of the present, at this time, I am trying to focus on learning what we actually know from observation of the present.

Good idea. We can take the concepts of evolution and observe them in the world around us: mutation is observed in the lab and in the wild; natural selection is observed in the lab and in the wild; speciation is observed in the lab and in the wild.

This was Darwin's insight - every species known has variations within the populations, natural selection would operate on those variations in a manner similar to the artificial selection of animal husbandry to produce adaptation to new or different ecologies, causing diversification in time and space, and finally - that this was sufficient to explain the fossil record.

You can think of the "Theory of Evolution" as the hypothesis that evolution - the change in the frequncy of hereditary traits in breeding populations from generation to generation - and the process of speciation - the division of a parent population into two or more reproductively isolated daughter populations - is sufficient to explain (a) the fossil record, and (b) the genetic record. As such the fossil record and the genetic record become tests of the theory, tests capable of falsifying the theory.

If you want to discuss how these can be applied to the fossil record in order to judge the validity of the evolutionary explanation, another of my threads addresses this in a different format:

Dogs will be Dogs wil be ??? - this uses the variation within the dog species as a metric to compare the variation between different fossil species, assuming that the variation seen in dog species is the maximum that can occur in a species, and then seeing if the difference between two or more closely related (in time and space and morphology) exhibit more or less variation than we see in dogs.

I am curious about that because horses and donkeys have different chromosome numbers and I would be interested as to what the explaination for that is (how did donkeys lose chromosones - or horses gain - not sure which way it happened).

Sometimes a chromosome (a collection of genes and proteins into a distinct substrand of DNA) divides, and sometimes two chromosomes fuse. As long as the two pieces can line up with the single piece during the reproductive process, viable offspring can occur (this would be how such a mutation would spread in a population). When subsequent mutations start making such line-ups irregular and difficult, the offspring are less viable and speciation can occur within a single population over time (this would be sympatric speciation).

This is also one of the differences between chimps and humans -
http://en.wikipedia.org/wiki/Chimpanzee_genome_project

quote:
Human and common chimpanzee chromosomes are very similar. The primary difference is that humans have one fewer pair of chromosomes than do other great apes. In the human evolutionary lineage, two ancestral ape chromosomes appear to have fused at their telomeres producing human chromosome two.[1] There are nine other major chromosomal differences between chimpanzees and humans: chromosome segment inversions on human chromosomes 1, 4, 5, 9, 12, 15, 16, 17, and 18. ....

The results of the chimpanzee genome project suggest that when ancestral chromosomes 2A and 2B fused to produce human chromosome 2, no genes were lost from the fused ends of 2A and 2B. At the site of fusion, there are approximately 150,000 base pairs of sequence not found in chimpanzee chromosomes 2A and 2B. Additional linked copies of the PGML/FOXD/CBWD genes exist elsewhere in the human genome, particularly near the p end of chromosome 9. This suggests that a copy of these genes may have been added to the end of the ancestral 2A or 2B prior to the fusion event. It remains to be determined if these inserted genes confer a selective advantage. ....


It's possible that this fusion event is what caused the eventual speciation division of these two branches from out common ancestor, and it is also possible that this occurred after such division.

Enjoy.


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 59 by herebedragons, posted 12-29-2009 2:14 PM herebedragons has responded

Replies to this message:
 Message 64 by herebedragons, posted 01-06-2010 11:46 AM RAZD has responded

  
RAZD
Member
Posts: 20156
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 4.1


Message 63 of 450 (541063)
12-31-2009 12:44 AM
Reply to: Message 41 by herebedragons
12-22-2009 2:13 PM


Re: for herebedragons - speciation, definition first, discussion second
Hi herebedragons, I'm going to pick up on some older points.

Although the most popular and widely excepted definition seems to be the Biological species concept, ...
... but both speciation and reproductive isolation remain problematic issues. "Reproductive isolation", widely considered an essential ingredient in defining the word species, is itself vaguely and inconsistently defined. Exactly when does reproductive isolation occur? what are the actual mechanisms that bring it about? is geographic isolation enough to develop reproductive isolation? what does “potentially” interbreeding individuals actually mean? etc. Truly “reproductive isolation” is quite ill defined.

In fully developed reproductive isolation interbreeding is impossible, so this is not problematic. When you have behavioral or geological isolation you have the beginning of isolation, where genetic incompatibility can occur and not be selected against. It's not a sudden occurrence.

Then throw into the mix hybridization.

See previous reply about variations in hybrid viability, which is also an ongoing process in some instances.

The author gave an analogy that I think clearly illustrates the problem and also the problem of presupposing or historically considering a form to be a separate species despite there ability to interbreed as are the Spanish sparrow (P. hispaniolensis) and the house sparrow [P. domesticus].

I have seen some bad analogies in my time, but this one is rather insulting to scientists. Aside from the issue that a species are generally not defined in relation to another species (exception: symbiology co-evoution, which includes the co-evolution of multicell organisms and the bacteria they carry, such as stomach that aid digestion - termites are termites because their gut has bacteria that digests wood cellulose), the implication that decisions like this are based on such simple whimsy is down-right false. There may be subjective elements involved, but the amount of detail that is documented before a new species is declared is voluminous in details of traits compared and relative differences noted - there is more to it than the observation that bone "A" is longer in specimen "B" than in specimen "C".

You realize that your "authority" is proposing a "new" theory on "On the Origins of New Forms of Life" yes? Interesting theory, but I predict it will be of marginal value in only some instances - instances where hybrids can form and speciation has not fully occurred, so this is really mixing up the breeding population after a short separation that develops some distinctive new traits. Once reproductive isolation occurs we are back in the same-old same-old. This is not a new concept, and several people have suggested similar ideas.

Message 43: My apologies, Mr. Jack, but what consitutes a "credible" source as opposed to a "crank website"? I am avoiding "creationist" sites as they are "crank" or "bogus". But this was not a creationist site.

It's a crank website because it promotes a personal hypothesis and apparently is the only source for this hyposthesis. Such things occur in all sciences, and it is easy for a person not educated in the science to be unaware of the basic problems and ramifications of these "new" hypothesis.

I only found one site that discussed this theory in comparison to the normal paradigm in biology:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2556406/
Three ambitious (and rather unorthodox) assignments for the field of biodiversity genetics, by John C. Avise (this hypothesis is only covered in the beginning sections, and is mostly considered as a means of testing the normal paradigm). It tells you how you can test for the validity of the hypothesis and what you should see in the genetic records.

It seems to me the concept of species is very illusive and there is no “one size fits all approach”. In addition, I’m not sure it has any value in the real world other than for our convenience in discussing different animals. IOW when I say ‘zebra’ you know I am talking about an animal that lives in Africa and has black and white stripes and when I say ‘horse’ you know I am talking about a domesticated animal that is primarily used for human recreation. Whether they are clearly distinct species may be irrelevant. The problem with a statement like that, from an evolutionist’s point of view, is that if a species distinction is irrelevant, that kinda makes speciation irrelevant too, since after speciation occurs the results would be irrelevant.

Not when we have reproductive isolation. Horses and zebras can interbreed (see zorse) just like horses and donkey, and with similar infertility as a result. Rather obviously these infertile hybrids are not going to be bringing new "stabilized" traits back to either horse or zebra population, and thus the time when this could be a factor in equid evolution has already passed for these species, and we have distinct different species - horse, zebra, donkey, quagga.

I have been doing some reading about DNA sequence analysis and feel there is a lot of promise to resolve some of these problems and give us a clearer picture of lineage and thus history, but I have a feeling evolutionists (specifically gradualists) and creationists alike are going to be disturbed by the results. Any other input on DNA sequencing would be helpful as I know very little about the terminology or theory behind it.

Or they will welcome the new additional data that by and large has verified to an amazing extent the tree of life pattern that has been derived from detailed morpological analysis, with some rearrangements in lineage being inevitable, but the overall pattern still holding. Remember that this is already done for some of the branches, such as humans, chimps and other apes, where the genomes are known for the different species, and a cladistical analysis based on the genetics results in a very similar cladistic analysis of the hereditary relationship previously developed through analysis of the fossil record.

Remember that the fossil record and the genetic record are both tests of the concept\hypothesis\ToE, that evolution (the change in frequency of hereditary traits in breeding populations from generation to generation) and speciation (the division of breeding populations into reproductively isolated daughter populations) are sufficient to explain the diversity of life as we know it, and thus when they give similar results this is validation of the theory.

Enjoy


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 41 by herebedragons, posted 12-22-2009 2:13 PM herebedragons has not yet responded

  
herebedragons
Member (Idle past 18 days)
Posts: 1513
From: Michigan
Joined: 11-22-2009


Message 64 of 450 (541798)
01-06-2010 11:46 AM
Reply to: Message 62 by RAZD
12-29-2009 10:37 PM


Re: Speciation discussion
Hi Razd. Sorry to hear about your long battle with cancer. I'msure it has been difficult.

Thanks for link to the Berkley series. It is very well done. I do appreciate how they clearly distinguish between what is theory, what are predictions based on the theory and what is actually observed. This is not always done in evolutionary literature.

What I've learned so far about species and speciation has been pretty unimpressive (and by unimpressive, I mean in an evolutionary sense - there are some truly remarkable things to learn about our world). I am looking for observations that I believe are clues to larger scale changes. I know you will be quick to point out that to see those types of changes we need to look at the fossil record as our time frame for observation is miniscule compared to evolutionary time scale. But what I find appears to be much more like variations within a species.

Take the species Brassica oleracea for example. I was shocked when learned that Kale, Broccoli, Cabbage and a dozen other disgusting vegetables were not just in the same family or even genus, but the same species! Just different cultivars. There is tremendous variation in these plants and the only thing they seem to have in common is they are nasty tasting lol. Is that truly evolution?

And of course, dogs and even horses exhibit drastic amounts of variation within species boundaries. It is duly noted that all above mentioned examples are due to human breeding and cultivation, not natural processes. But also note that human breeding and cultivating is a intelligent, directed process - not undirected and random. Can an undirected, random process create so much diversity? I know, I know ... given enough time it can.

I found this article that was published in PNAS December 22, 2009 (I could not access the actual article as it requires a subscription, but this abstract was posted in several places)

http://www.biologynews.net/..._light_on_horse_evolution.html

quote:
Ancient DNA retrieved from extinct horse species from around the world has challenged one of the textbook examples of evolution ¡V the fossil record of the horse family Equidae over the past 55 million years.

"Overall, the new genetic results suggest that we have under-estimated how much a single species can vary over time and space, and mistakenly assumed more diversity among extinct species of megafauna,"


Their research doesn't discredit the evolution of the horse, but sheds light on the amount of diversity that has occurred within a species over time. Analysis of lineages based on good old fashioned morphology is questionable. We are looking back though millions and millions of years and that has to get a bit fuzzy.

Another example is the reorganization in the metazoan phylogenetic tree.

quote:
DNA sequence analysis dictates new interpretation of phylogenic trees. Taxa that were once thought to represent successive grades of complexity at the base of the metazoan tree are being displaced to much higher positions inside the tree. This leaves no evolutionary "intermediates" and forces us to rethink the genesis of bilaterian complexity.

http://www.pnas.org/content/97/9/4453.full

I won't repeat the details, but the characteristics that were once thought to unite organisms and provide evidence of an evolutionary path, are now being found to be invalid. It is being discovered that it is actually a different set of characteristics that unite the groups.

Another good example of this is the coelacanth. It was once thought that this fish was the predecessor to land animals. It was believed that it used its boney fins to walk along the sea bottom and it had developed a "primitive" lung. With the discovery of living examples of this species, we now know that neither of these assumptions to be true.

quote:
"The modern coelancanth ... has been popularly acclaimed as a "living fossil" and a "missing link" between fishes and tetrapods. This reputation is based on outdated classification and systematic methods, anecdotal evidence and scant regard for intermediate fossil relatives, most of which were described long before Latimeria was discovered... The coelacanth lineage must now be regarded as more distantly related to tetrapods than previously thought... - History of the coelacanth fishes by Peter L. Forey

Even a 1986 encyclopedia (why do I have a set of 20+ year old encyclopedias? My wife got a "deal" on them at a garage sale. Thanks honey ) still held that coelacanths gave rise to land animals and they could "walk" on their fins. What would we believe today if living coelacanths were not discovered? We would be, at the least, looking down the wrong evolutionary path. It is this kind of "dogma" - meaning that once a line of thought becomes ingrained it becomes very difficult to dislodge that line of thinking - that led me to comment on the dog / flea analogy, to which you commented:

I have seen some bad analogies in my time, but this one is rather insulting to scientists.

I certainly didn't mean to insult scientific intelligence or even to insult the scientific process. However, what I do say is that scientists are still human. They are still swayed by the same powers of suggestion, egotism, self-interest and emotions as are all the rest of us. To paint scientists as Mr. Spock types, that deal unemotionally with the "just the facts" would be mistaken. Then take into consideration what then becomes a popular public image, such as coelacanths walking on the ocean floor, or artistic drawings and descriptions of primitive man and other "assumptions" or "speculations" that science regards as only theories or guesses, but can easily become popular images and it can often be difficult to change public or laymen perception.

I do believe scientists are open to the facts and when such facts are presented they adjust their hypothesis or understanding accordingly. (But sometime, public understanding doesn't keep up)

Or they will welcome the new additional data that by and large has verified to an amazing extent the tree of life pattern that has been derived from detailed morpological analysis, with some rearrangements in lineage being inevitable, but the overall pattern still holding.

So when I said they would be "disturbed" at the new DNA results I probably choose the wrong word. I should have said more like "shocked". I also predict that findings based on mitochondrial rRNA will be upset when a new and better test is developed in 10 - 20 years. That's something amazing about science: that whenever one question is "answered" it creates two or more unanswered questions on a never ending quest. That's what keeps scientists going. That's what makes it exciting - no matter how much we think we know, there will always be infinitely more to know than we can even imagine. I guess you could say God is always one or two steps ahead of us .

I think I am going to start looking at the fossil record now. Any suggestions? I have found a couple of really cool sources for fossil pictures, but how can I be sure they are authentic? Particularly the dates are questionable. How can I know dates are reported correctly?

Example: http://www.fossil-museum.com/fossils/

Aside from the fact that they are trying to disprove evolution using the fossils they have on record, are they identified and dated accurately? One thing that caused me concern was they did not use binominal names. They say for example "this is a 30 million year old rabbit" A rabbit? What kind of rabbit? And it's not just this site but most sites with pictures I found. I don't know, so how can I know that fossils are represented accurately?

Thanks


This message is a reply to:
 Message 62 by RAZD, posted 12-29-2009 10:37 PM RAZD has responded

Replies to this message:
 Message 65 by hooah212002, posted 01-06-2010 12:28 PM herebedragons has responded
 Message 66 by RAZD, posted 01-06-2010 10:50 PM herebedragons has responded
 Message 69 by RAZD, posted 01-07-2010 9:30 PM herebedragons has responded
 Message 71 by deerbreh, posted 01-08-2010 4:05 PM herebedragons has not yet responded

  
hooah212002
Member (Idle past 108 days)
Posts: 3183
Joined: 08-12-2009


Message 65 of 450 (541804)
01-06-2010 12:28 PM
Reply to: Message 64 by herebedragons
01-06-2010 11:46 AM


Re: Speciation discussion
Example: http://www.fossil-museum.com/fossils/p

PLEASE PLEASE PLEASE!!! You seem interested in facts, evidence proof and the like. Why would you entertain the idea of learning properly about fossils from such a biased site?


Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people
-Carl Sagan

For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
-Carl Sagan


This message is a reply to:
 Message 64 by herebedragons, posted 01-06-2010 11:46 AM herebedragons has responded

Replies to this message:
 Message 67 by herebedragons, posted 01-07-2010 8:47 AM hooah212002 has acknowledged this reply

    
RAZD
Member
Posts: 20156
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 4.1


(1)
Message 66 of 450 (541938)
01-06-2010 10:50 PM
Reply to: Message 64 by herebedragons
01-06-2010 11:46 AM


Re: Speciation discussion
Hi herebedragons,

I'll have to get back to you tomorrow, but just a quick note:

Example: http://www.fossil-museum.com/fossils/

Harun Yahya is a convicted fraud, not someone I would trust with the truth. His "atlas of creation" shows a fishing lure as an example of a living bug.

http://richarddawkins.net/articles/2833

One needs to be skeptical of sources that seem to provide the evidence you want while ignoring the rest of the story.

Tomorrow we will get back to species.

enjoy.


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 64 by herebedragons, posted 01-06-2010 11:46 AM herebedragons has responded

Replies to this message:
 Message 68 by herebedragons, posted 01-07-2010 9:03 AM RAZD has acknowledged this reply

  
herebedragons
Member (Idle past 18 days)
Posts: 1513
From: Michigan
Joined: 11-22-2009


Message 67 of 450 (542008)
01-07-2010 8:47 AM
Reply to: Message 65 by hooah212002
01-06-2010 12:28 PM


Re: Speciation discussion
Thanks Hooah, but I was looking for suggestions on where I should look and you responded with only an argument of personal incredulity. Also, I was already skeptical of the site because it seemed just too unscientific. Notice I commented that the author did not use scientific names? It really is beautifully illustrated though. So if you want to help, please, please, please give me something I can actually use.

See Message 66 from Razd


This message is a reply to:
 Message 65 by hooah212002, posted 01-06-2010 12:28 PM hooah212002 has acknowledged this reply

  
herebedragons
Member (Idle past 18 days)
Posts: 1513
From: Michigan
Joined: 11-22-2009


Message 68 of 450 (542011)
01-07-2010 9:03 AM
Reply to: Message 66 by RAZD
01-06-2010 10:50 PM


Re: Speciation discussion
Thanks Razd. For some reason I was not able to find any comments about fossil-museum.com, but I didn't look for "atlas of creation". I was skeptical because it just seemed too unscientific. I expected some dates to be manipulated or some specimens to be misrepresented slightly, but FISHING LURES????

It wasn't so much that it "provided the evidence I wanted" (I wouldn't try to claim that organisms don't change over time - what I am skeptical of is how much they change) but it looked like a very well done project with a very extensive collection. And it would seem anyone that spent that much in producing a work like that would have spent some time doing the research too. But, I guess not. It still makes for some pretty pictures though

Thanks


This message is a reply to:
 Message 66 by RAZD, posted 01-06-2010 10:50 PM RAZD has acknowledged this reply

  
RAZD
Member
Posts: 20156
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 4.1


Message 69 of 450 (542144)
01-07-2010 9:30 PM
Reply to: Message 64 by herebedragons
01-06-2010 11:46 AM


Re: Speciation discussion, expectations and reality
Hi again herebedragons, I have some time now to concentrate on the issue of speciation.

Thanks for link to the Berkley series. It is very well done. I do appreciate how they clearly distinguish between what is theory, what are predictions based on the theory and what is actually observed. This is not always done in evolutionary literature.

Frankly, I have never had a problem distinguishing the two, nor do I think any of my classes (back through high school) ever conflated them. I have always found this assertion by creationists to be curious, almost as if they were creationists because they were victims of bad education.

But yes, I think Berkeley has the best website on the internet to explain evolution in clear discrete articles.

What I've learned so far about species and speciation has been pretty unimpressive (and by unimpressive, I mean in an evolutionary sense - there are some truly remarkable things to learn about our world). I am looking for observations that I believe are clues to larger scale changes. I know you will be quick to point out that to see those types of changes we need to look at the fossil record as our time frame for observation is miniscule compared to evolutionary time scale. But what I find appears to be much more like variations within a species.

Before we go there, let's explore why you think there should be "larger scale changes" - how much "larger" and how do you define the scale of change? Certainly there is no known "other mechanism" to cause change, regardless of size, so we are left with normal evolutionary mechanisms.

Take the species Brassica oleracea for example. I was shocked when learned that Kale, Broccoli, Cabbage and a dozen other disgusting vegetables were not just in the same family or even genus, but the same species! Just different cultivars. There is tremendous variation in these plants and the only thing they seem to have in common is they are nasty tasting lol. Is that truly evolution?

And of course, dogs and even horses exhibit drastic amounts of variation within species boundaries. It is duly noted that all above mentioned examples are due to human breeding and cultivation, not natural processes. But also note that human breeding and cultivating is a intelligent, directed process - not undirected and random. Can an undirected, random process create so much diversity?

Personally I doubt that the extreme variations selected artificially would be found in nature to produce the same degree of variety at any one time, but what this shows is just how much variation can happen in short periods of time (geologically speaking). We can take this as a metric for how much time is needed as a minimum to go from {average\original condition} to an {extreme condition}. In fact I have proposed doing this on the Dogs will be Dogs wil be ??? thread.

We can also see where selection for one particular trait can lead to some rather interesting developments in a fairly short period of time:

http://cbsu.tc.cornell.edu/ccgr/behaviour/History.htm

quote:
The silver fox (Vulpes vulpes) is taxonomically close to the dog (Wayne, 2001) but although reared in captivity, they had not been domesticated previously. Under standard farm conditions foxes normally exhibit distinct patterns of aggressive and fear-aggressive behavior to humans. Dmitriy Belyaev, and colleagues hypothesized that a selection of farm foxes for less-fearful and less-aggressive behavior would yield a strain of domesticated fox (Belyaev 1969, 1979; Trut, 1999).

Selection for tame behavior was started at the Institute of Cytology and Genetics (ICG) in Novosibirsk, Russia in 1959 with 130 farm-bred foxes that demonstrated the least avoidance behavior towards humans. Subsequently, only the tamest individuals in each generation have been allowed to breed, while at the same time a deliberate effort was made to avoid inbreeding (Trut, 1999, 2001; Trut et al., 2004). The tame population developed relatively fast in response to selection - with 18 percent of foxes from the tenth generation demonstrated extremely tame behavior. Little behavioral variation was observed by 1985 and thereafter (Trut, 1999, 2001; Trut et al., 2004).


So in a fairly short period of time, selection only on the basis of tame behavior led to a rapid increase in tame behavior within the (allowed) breeding population. But this simple statement doesn't tell you what else occurred:

https://www.youtube.com/watch?v=enrLSfxTqZ0

Of course many of those traits don't appear in fossils, so it is hard to correlate this with the history of dogs without having additional evidence (such as pictographs of dogs) that similar changes occurred. Note that many of these trait changes are also what we see in cows and pigs and cats, and other domesticated animals.

This is the area covered by evolutionary development - evo-devo - a fairly new field, where changes in hormones or environmental chemicals can affect the way organisms develop from fetus to adult. See also thalidomide.

This is important, because natural selection operates on the phenotype - the 'as-built' form of the individual - rather than the genotype. Anything that affects the phenotype that is not part of the genotype can thus be important for selection processes, and the genetics of the selected individuals are more or less along for the ride (neutral drift).

Some people feel that evo-devo is responsible for the more dramatic changes in evolutionary history (including possibly the first formation of vertebrates).

Their research doesn't discredit the evolution of the horse, but sheds light on the amount of diversity that has occurred within a species over time. Analysis of lineages based on good old fashioned morphology is questionable.

Curiously the evolution of horses has seen some re-evaluation based on morphology that shows more variation than had been supposed 50 years ago.

http://www.flmnh.ufl.edu/natsci/vertpaleo/fhc/Stratmap1.htm

Note that the groupings show are the different genera, with species being even more varied (and variations within species another level of variation).

Their research doesn't discredit the evolution of the horse, but sheds light on the amount of diversity that has occurred within a species over time.

Now we can argue that the morphological analysis centers on the average of the population in the record, and that all this new information means, is that there is a wider circle around that average position at any point in time. Then as we shift through the time layers to the next set of fossils we see the same average plus wider circle around that average position, and thus are more likely to have clear overlaps from one layer (age) to the next layer (age) making the transition from one to the other even more likely.

This is similar to the Pelycodus example in Message 57 where the overlap in sizes from layer to layer show clearly the transition from one population group to the next to the next.

So we see that a fair degree of variation can exist in a breeding population at any one time, and we see that a fairly remarkable degree of change can occur in a breeding population subject to constant selection pressure in a fairly short period of time.

Then we can compare this to the degree of change seen in the fossil record to see if this rate of variation and change are sufficient to explain the change from one age layer to the next age layer in a population of fossils that share morphologically homologous structures.

If this is sufficient to explain the fossil evidence then no "larger scale changes" are necessary. Do you agree, or do you want to see more change spread out over more time?

I know you will be quick to point out that to see those types of changes we need to look at the fossil record as our time frame for observation is miniscule compared to evolutionary time scale.

Certainly to see more change than is observed in these examples of rapid evolution seen within our minuscule time frame. Most evolution is your ordinary "unimpressive" kind as there is no severe selection pressure and what selection pressure occurs is usually not constant but varying, resulting in a "staggering drunken walk" to get from point "A" to point "B" (and no clear reason to go there).

How much more change is needed?

Enjoy.


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Wounded King
Member (Idle past 2381 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 70 of 450 (542270)
01-08-2010 2:51 PM
Reply to: Message 69 by RAZD
01-07-2010 9:30 PM


Misrepresenting evo-devo
This is the area covered by evolutionary development - evo-devo - a fairly new field, where changes in hormones or environmental chemicals can affect the way organisms develop from fetus to adult.

This is a tiny proportion of what evo-devo covers. In fact something like the action/effects of Thalidomide is simply a developmental question, evolution doesn't come into it, except to the extent that perturbing normal development helps us understand the underlying developmental networks which are the principle substrate for the generation of heritable morphological variation.

You seem to be ignoring the whole developmental genetics aspect which is arguably the core of evo-devo. To make out that evo-devo is somehow removed from consideration of the genotype is very misleading.

TTFN,

WK


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 Message 69 by RAZD, posted 01-07-2010 9:30 PM RAZD has acknowledged this reply

    
deerbreh
Member (Idle past 1179 days)
Posts: 882
Joined: 06-22-2005


Message 71 of 450 (542283)
01-08-2010 4:05 PM
Reply to: Message 64 by herebedragons
01-06-2010 11:46 AM


Re: Speciation discussion
Can an undirected, random process create so much diversity?

Well evolution is actually neither undirected nor random.

Direction is created by selection pressure.

Ever hear of parallel evolution? Look it up. It pretty much disproves your premise.

Favorable traits are selected for - there is nothing random about that.
That is why we can measure aspects of the environment and predict what kinds of animals and plants should be found there. If it were random it would not be so predictable.

There is some randomness associated with mutation events but even mutation is not completely random. Certain loci are more susceptible to mutation than others.


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herebedragons
Member (Idle past 18 days)
Posts: 1513
From: Michigan
Joined: 11-22-2009


Message 72 of 450 (543960)
01-22-2010 11:15 AM
Reply to: Message 69 by RAZD
01-07-2010 9:30 PM


Re: Speciation discussion, expectations and reality
Hi Razd. Now it's my turn to apologize for taking so long to respond.

How much more change is needed?

Needed for what? To convince me that the ToE is accurate and is the best explanation for life on this planet? To convince me that creation is a myth? Or that God doesn't exist? Or simply to convince me that organisms change over time?

I am convinced that organisms change over time. It's obvious they do. What I am not convinced of is the extent of change. Fish --> Amphibians; Theropods --> Birds; Chimps --> Humans. Now be honest, just based on what we've discussed so far would it be enough to convince you if you were skeptical? I don't know how long you have been studying evolutionary biology, but it is obvious that you have a lot of knowledge on the subject and it may be hard for you to see this from my point of view. But I am having a hard time taking observed evolution and extrapolating that into the kind of changes mentioned above. (note that I am still investigating and learning about this, not declaring victory or proclaiming that the ToE is false)

One of the major things I am having the hardest time wrapping my mind around is the idea of random mutations being the source for new biological innovations. Let's consider the example of E. coli bacteria developing a new metabolic pathway. Here is my paraphrase of how it happens. E. coli is introduced to an environment with a food source that it normally does not metabolize. During the first several hundred generations, random mutations are occurring until at about 400 generations it hits on one that improves its ability to metabolize the new food source. It can then metabolize the new food source and grow at a normal rate.

I picture a "random mutation generator" functioning much like a program they use in movies to decode passwords, trying thousands of combinations until one works. Maybe this isn't very realistic, but still, there would be literally thousands, maybe hundreds of thousands, of mutations that could occur until by chance it stumbles upon the right mutation that works. This seems to me highly improbable and I don't think we observe the rate of mutation that would be needed to make it realistically probable. I don't think it was discussed how many times the experiment was repeated, but I assume the experiment is repeatable with the same general results, which makes the probability that this would happen randomly over and over even more unlikely.

Additionally, I saw no mention of any other mutations that occurred during the study. The only one that was noted was the metabolic pathway. The law of probability would dictate that other mutations are just as likely to occur, even when you take selection into account. I am sure neutral mutations did occur, but there must be other beneficial mutations that could have occurred instead of, or in addition to, the metabolic pathway mutation. When the experiment is repeated, you should see other randommutations occuring.

Another problem I have is that in nature the environment would not likely be stable enough to give the organism time to come up with a mutation randomly. The levels of the food source would fluctuate and other environmental forces would compete for the organisms "attention".

All in all, the probability that this pathway evolved randomly seems mind boggling to me. And that's just a fairly simple (biologically speaking) change. The probabilities increase exponentially with more and more complicated systems requiring many different cell structures and proteins and such.

A more likely explanation would be that the information for the new pathway was already contained in the genome and the change in environment caused it to be turned on like a switch. I would be interested to know if the E. coli that had developed the new pathway could go back to using the original pathway. Would it have to re-evolve by random mutations? Or does it still exist in the coding?

The variation in dog breeds and the B. oleracea species would be another indication of this. There are large amounts of morphological differences and yet very little genetic distance. This would indicate that the information was already contained in the DNA and selection merely changed what genes were expressed. What happened with the silver fox also supports this. First of all, the trait for tameness did exist in the silver fox population (they selected for the tamest individuals - although in this case tameness is a relative term). Secondly, after they managed to tame the population (domesticate) they exhibited many of the same complementary traits that dogs exhibit. Is this a coincidence? What are the chances that this was random? It seems highly, highly improbable to me. Ancestry could explain it, but enough genetic variation should have accumulated to make it somewhat less likely that they would exhibit similar complementary traits.

We do know mutations occur as we can observe them and do comparative studies, but do we truly know the source of these mutations? Why do genes mutate? Are they random or driven by environmental forces? Or maybe both with less emphasis on randomness.

I admit that I only know enough about genetics to make myself look foolish and I need to do much more research on the subject. But, from what I have read so far on evo-devo and epigenetics it seems to have the potential to be revolutionary to evolutionary science. I also might add, somewhat hesitantly, that if IDers and creation scientists would get involved in this kind of science (or any science for that matter) it may have the potential to revolutionize their claims too.

Well, I don't have any more time right now, but hopefully by the next time I post, I will be able to talk a little bit more intelligently about the genetic issues I brought up.

Again, thanks for your time and patience in discussing this with me.

Take care


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greyseal
Member (Idle past 2148 days)
Posts: 464
Joined: 08-11-2009


Message 73 of 450 (543986)
01-22-2010 4:01 PM
Reply to: Message 72 by herebedragons
01-22-2010 11:15 AM


Re: Speciation discussion, expectations and reality
How much more change is needed?

Needed for what? To convince me that the ToE is accurate and is the best explanation for life on this planet? To convince me that creation is a myth? Or that God doesn't exist? Or simply to convince me that organisms change over time?

the ToE is not an explanation of abiogenesis, it only explains the diversity of life on this planet. The ToE is correct whether god made everything or whether we all originated in the big bang. Similarly, the existence of god has nothing to do with the ToE.

I am convinced that organisms change over time. It's obvious they do. What I am not convinced of is the extent of change.

good, then you believe in evolution - likely you call it "microevolution". there is no difference between that and "real" evolution, only time. If you feel the earth is not 4.5 billion years but rather <10,000 then we have a problem

One of the major things I am having the hardest time wrapping my mind around is the idea of random mutations being the source for new biological innovations. Let's consider the example of E. coli bacteria developing a new metabolic pathway. Here is my paraphrase of how it happens. E. coli is introduced to an environment with a food source that it normally does not metabolize. During the first several hundred generations, random mutations are occurring until at about 400 generations it hits on one that improves its ability to metabolize the new food source. It can then metabolize the new food source and grow at a normal rate.

Remember, it's not one bacteria, it is a colony of millions, perhaps billions, and they're all evolving at once. The ones that do not metabolyze their food do not do so well and do not reproduce as fast. the ones that metabolyze it better reproduce faster and more. This is an inexorable pressure towards those who can survive, weeding out the ones that can't by - you guessed it - natural selection; they die if they can't survive. If they die, no offspring.

There is no passing on of the secret between bacteria, only from parent to offspring. there is no guided hand there, only blind chance and the ability of life to do what it does.

when the pressure for change is off (i.e. the remainder of the bacteria can metabolyze the new food because the ones that can't are dead) then less will die, meaning that whilst they are STILL evolving, there won't be such a marked change as when this threshold was introduced. no pressure on the colony, no special behaviour and ability being rewarded, no pressure for any other type to arise than what's already there. That doesn't mean they don't try and it doesn't mean they won't, but with less pressure you'll not measure change quite so easily as mass death of those inable to survive can show you.

I picture a "random mutation generator" functioning much like a program they use in movies to decode passwords, trying thousands of combinations until one works. Maybe this isn't very realistic, but still, there would be literally thousands, maybe hundreds of thousands, of mutations that could occur until by chance it stumbles upon the right mutation that works.

you're right, it's bad. there is no mutation like you seem to be indicating, these are not pokemon. There's no flash of light. there's just millions and billions of these mutations happening every second, continuously. with even a slight advantage, parts of the answer will be found very, very quickly. mistakes will be fatal very, very quickly.

The reason they didn't talk about any other sorts of mutations is because, well, how would you check for it?

It's easy to see if a bad food source slows down growth of colonies billions of bacteria in size, but not so easy to see if there's some funky stuff going on that, for example, might solve a disease you have no intentions of testing it against.

They weren't looking for anything else, and it wasn't relevant. You'll have to trust me on that if you can't understand why.

Cheers,

Daniel.


This message is a reply to:
 Message 72 by herebedragons, posted 01-22-2010 11:15 AM herebedragons has not yet responded

    
Wounded King
Member (Idle past 2381 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 74 of 450 (543994)
01-22-2010 4:42 PM
Reply to: Message 72 by herebedragons
01-22-2010 11:15 AM


Re: Speciation discussion, expectations and reality
Why do genes mutate? Are they random or driven by environmental forces?

The answer to this is 'both', the mutation rate and indeed the differential rates of different types of mutations can be heavily influenced by environmental factors.

However these factors do not target mutations to any particular gene or locus, which is why the mutations are random.

TTFN,

WK


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 Message 72 by herebedragons, posted 01-22-2010 11:15 AM herebedragons has not yet responded

    
RAZD
Member
Posts: 20156
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 4.1


Message 75 of 450 (544005)
01-22-2010 7:56 PM
Reply to: Message 72 by herebedragons
01-22-2010 11:15 AM


Re: Speciation discussion, mutations, possibilities and opportunity
Hi again, herebedragons.

Now it's my turn to apologize for taking so long to respond.

No need, this pace suits me, and it allows for digestion of information before proceeding to the next level, and better understanding of your concerns.

How much more change is needed?

Needed for what? To convince me that the ToE is accurate and is the best explanation for life on this planet? To convince me that creation is a myth? Or that God doesn't exist? Or simply to convince me that organisms change over time?

I am convinced that organisms change over time. It's obvious they do. What I am not convinced of is the extent of change. Fish --> Amphibians; Theropods --> Birds; Chimps --> Humans.
...
But I am having a hard time taking observed evolution and extrapolating that into the kind of changes mentioned above.

And so we shall endeavor (eventually) to focus on this "macro" level of change, noting that macroevolution occurs above the level of (ie after) speciation, to show that evolution can explain the diversity of life as we know it, including the transition from fish to amphibian, therapod to bird, or ancestral apes into chimps and humans. We may need to move to another thread to discuss this (perhaps the Dogs will be Dogs wil be ??? thread as a start).

The rest will be for you to decide, however please note that I am a Deist, not an atheist.

Now be honest, just based on what we've discussed so far would it be enough to convince you if you were skeptical?

The observed process of evolution -- the change in the frequency of hereditary traits in breeding populations from generation to generation -- is the foundation. We agree that this occurs, and now we can build on that foundation.

The next stage is to show how this leads to speciation (which will return us to the topic here).

One of the major things I am having the hardest time wrapping my mind around is the idea of random mutations being the source for new biological innovations.

Let us consider the source of mutations first then, and their role in the evolutionary process.

The major source of mutations is imperfect replication: during reproduction the DNA of the parent is imperfectly replicated in the cells for the offspring. This occurs in every cell reproduction, but is most relevant to evolution in the reproduction process, the formation of the germ (sperm and egg sex) cells or the bud (asexual) cells. Again, this is an observed process in all known life forms.

I picture a "random mutation generator" functioning much like a program they use in movies to decode passwords, trying thousands of combinations until one works. Maybe this isn't very realistic, but still, there would be literally thousands, maybe hundreds of thousands, of mutations that could occur until by chance it stumbles upon the right mutation that works.

This is a common argument from improbability, however there are a couple of problems with it, not least of which is that there can be millions of potential solutions -- different mutations in different parts of the DNA that can result in usage of the substrate provided. Another is that the target is not a random chemical, but a known organic compound (amino acid iirc), and there may be hundreds of different ways to utilize this particular organic compound. All evolution needs is A way to utilize the compound, and the method found does not need to be the most efficient either, just functionally superior to not using it (resulting in a net increase in energy from the compound to the organism). Further mutations can refine the process and improve the efficiency.

In this one case we are talking about some 400 generations and many thousands of descendant organisms from a single parent organism, each with many mutations, so there are a lot of opportunities involved. How many times do you need to throw 10 dice to get all 6's? The probability of it occurring increases with the number of throws. It could happen on the first throw or the 400th (such is the nature of probability).

This probability seems small if only one specific mutation is required at one specific location, however if all that is needed is one specific DNA combination to make use of the second substrate, there are many ways to derive that specific combination by various recombinations (mutations) of existing DNA. With each additional possibility the likelihood of one of those being found increases dramatically. How many times do you need to throw three dice to get three 6's?

Additionally, I saw no mention of any other mutations that occurred during the study. The only one that was noted was the metabolic pathway. The law of probability would dictate that other mutations are just as likely to occur, even when you take selection into account. I am sure neutral mutations did occur, but there must be other beneficial mutations that could have occurred instead of, or in addition to, the metabolic pathway mutation. When the experiment is repeated, you should see other randommutations occuring.

Indeed. As I recall, the mutation at the 400th generation made use of a previous neutral mutation, and only those populations with that particular neutral mutation could evolve to use the substrate. Neutral mutations are the most numerous in surviving organisms (the deleterious ones that kill organisms having done their work, and being largely unnoticed by the absence of cells that don't form).

Quite often mutations are neutral in their original environment, but then are beneficial or deleterious in a new one.

Another problem I have is that in nature the environment would not likely be stable enough to give the organism time to come up with a mutation randomly. The levels of the food source would fluctuate and other environmental forces would compete for the organisms "attention".

Organisms do not "come up" with mutations. Do not think of mutations as having to occur, rather that they happen, and that whatever happens provides an opportunity to be useful, neutral, or harmful.

Ecologies usually fluctuate around average conditions, and thus you can have repeated occurrences of ecologies where specific mutations may provide an opportunity for benefit to the organisms that have the mutation, but which are neutral in intervening periods. This would increase the time for such mutations to be of benefit to the breeding population, so in the wild it may take more than 400 generations to have an opportunistic mutation.

All in all, the probability that this pathway evolved randomly seems mind boggling to me. And that's just a fairly simple (biologically speaking) change.

And yet, experiment after experiment after experiment confirms that such opportunistic mutations do occur, and that they occur in sufficient frequency that they can be observed and documented. That something is "mind boggling" is not any criteria on which to base a scientific conclusion (else much of physics and chemistry would be discarded), and it can be due to ignorance of the actual possibilities, or just being uninformed. Nature cannot be expected to be expected.

A more likely explanation would be that the information for the new pathway was already contained in the genome and the change in environment caused it to be turned on like a switch.

More likely? Then why does it take (a) 400 generations for one E. coli. to develop the mutation that (b) requires a previous neutral mutation, and (c) does not occur in the millions of other E. coli. organisms that are part of the study? What about the ones that fail to find a mutation -- they would have had the same "pathway ... already contained in the genome" and they are subject to the same "change in environment" to cause "it to be turned on like a switch" would they not, -- if this were the case? A single organism succeeds in surviving on the second substrate, but the millions of others somehow can't find that very same previous pathway locked in their DNA? Remember that in science the best explanation is the one that explains all the evidence -- the failures as well as the successes.

I would be interested to know if the E. coli that had developed the new pathway could go back to using the original pathway. Would it have to re-evolve by random mutations? Or does it still exist in the coding?

It is possible for point mutations to reverse (undo), but in general evolution does not work in reverse. Similar paths may evolve, but are not likely to repeat previous systems. As an example, there are also experiments done where an existing path is deactivated, and a new path is evolved, with a different efficiency than previous, but still able to derive a net benefit. See Irreducible Complexity, Information Loss and Barry Hall's experiments for an example, one that also involves an "irreducibly complex" mechanism, and where the new system is less efficient than the original.

The variation in dog breeds and the B. oleracea species would be another indication of this. There are large amounts of morphological differences and yet very little genetic distance. This would indicate that the information was already contained in the DNA and selection merely changed what genes were expressed.

Or that small differences during development can have significant effects on the fully developed organisms. What was selected was different levels of adrenaline in the parents, a hormone that directly affects development in the womb.

Again, this took several generations to realize the result, it did not happen in the second generation, because natural levels of adrenaline was higher in all original foxes.

First of all, the trait for tameness did exist in the silver fox population (they selected for the tamest individuals - although in this case tameness is a relative term).

The trait for "tameness" did not exist. None of the wild foxes behaved in a tame manner. There were different levels of aggressive behavior, and they selected for the least aggressive.

Secondly, after they managed to tame the population (domesticate) they exhibited many of the same complementary traits that dogs exhibit. Is this a coincidence? What are the chances that this was random? It seems highly, highly improbable to me. Ancestry could explain it, but enough genetic variation should have accumulated to make it somewhat less likely that they would exhibit similar complementary traits.

Interestingly, this same pattern of coloration, floppy ears, and behavioral changes are also seen in other domesticated mammals - cats, pigs, horses, cows, sheep, etc. In all these cases the measured level of adrenaline is lower in the domestic stock than in the wild stock, and thus the explanation, that the different levels of adrenaline during development of the fetus, is a more likely explanation for all these instances, rather than some archaic ancestral preserved segment of DNA, that somehow miraculously survives in all these species from their remote common ancestor. In other words, you will need to already accept the macroevolution of mammals from a common ancestor in the distant past to propose that this mechanism explains the changes observed via preserved DNA. You would also, it seems to me, need some mutation mechanism to activate it, or it would remain hidden.

Again, if we want to continue to discuss the macro aspects of this, we should be moving to another thread (perhaps the Dogs will be Dogs wil be ??? thread before moving on to the further macroevolution mentioned above).

Let us conclude with mutations first eh?

So we have mutations, randomly occuring in populations providing some organisms with occasional beneficial opportunities, but the vast majority being neutral or not beneficial, ...

... or we have some unknown mechanism that preserves some unknown unused archaic ancestral DNA for millions of generations until it is needed by one out of thousands of equally deserving descendant organisms?

... the information ... was already contained in the genome and the change in environment caused it to be turned on like a switch.
This would indicate that the information was already contained in the DNA and selection merely changed what genes were expressed.

The DNA can be (and has been) compared between the original single E. coli. organism and the descendent ones that make use of the second substrate, and the result is that there are sections in the descendents that did not exist in the original: by what magic do these new segments appear out of their ancestral hiding place? How does this "switch" work?

You claim that this "hidden DNA" explanation is "more likely" and I have trouble seeing how it is even possible.

I am convinced that organisms change over time. It's obvious they do. What I am not convinced of is the extent of change.

For the purpose of this thread, we will need to show the degree of change necessary to result in speciation, the division of a parent population into reproductively isolated daughter populations, by the process of evolution. This occurs through mutation and natural selection operating on the sub-populations in different ways, and to understand this we need to understand how mutation operates in populations to provide opportunities.

We have seen an example of one mutation occurring in 1/400 generations in 1/1,000,000's of individuals being beneficial to the organism and its descendants. We have also seen selection of different levels of hormones in a population having an effect on the morphological development of following generations in a fairly rapid (relatively speaking) pace.

The first involves mutation, the second involves selection, and together they accomplish more than either can alone.

Enjoy.

Edited by RAZD, : clrty

Edited by RAZD, : first throw.

Edited by RAZD, : 3-6's


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

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 Message 76 by Coyote, posted 01-22-2010 8:20 PM RAZD has responded
 Message 78 by herebedragons, posted 02-08-2010 11:08 AM RAZD has responded
 Message 79 by herebedragons, posted 02-09-2010 2:33 PM RAZD has acknowledged this reply

  
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