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Author Topic:   Question on how Evolution works to produce new characteristics
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 18 of 104 (563766)
06-06-2010 7:06 PM
Reply to: Message 1 by Europa
06-05-2010 10:24 PM


Hi Europa and welcome to the fray,
I am confused about all the information on evolution, creation and intelligent design. Hence I joined this forum to post this question.
An excellent approach, let's see if we can help out.
Let me add to what others have said, with attention to some details:
But there is not a single orange speckled frog so far in this island population.
Evolution does not occur on demand, mutations are not produced to fit changing ecologies, but are random events.
Message 5 ... will it not be a response to a 'felt need'?
There is no "felt need" as there is no mechanism to feel it. Selection operates on traits existing in a population, and mutation is a random event that may provide a beneficial trait, a deleterious trait, or a neutral trait in the descendents.

Lamarkism

(Lmarkism?)
Message 8 1. Why do you say this -- orange speckling -- isn't Lamarkism?
Message 11 The often quoted example of Lamarkism is the elongation of a giraffe's neck. Now, the giraffe did not 'learn' how to have a long neck. But this is Lamarkism.
Well first it isn't an acquired trait so it doesn't fit his (best known) theory\model of inheritance of acquired traits. Another of his (less well known) theories was that the environment drove changes:
Jean-Baptiste Lamarck - Wikipedia
quote:
... that the environment gives rise to changes in animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of this principle.
Both of these processes have been falsified. In the example of the giraffe, we have a growing giraffe that stretches it's neck, and much like you or can excercise and build muscles, or loosen joints to stretch, this giraffe becomes able to reach further that previously.
In order to pass on this trait to it's offspring, there needs to be a mechanism that takes this acquired trait and somehow transfers it into the DNA of its sex reproduction cells. There is no such mechanism known.
I am confused about all the information on evolution, creation and intelligent design.
Curiously, you have asked more about Lamarkism than about any of these, so perhaps we need to clarify what each is first:

Evolution

Evolution is the change in the frequency and character of hereditary traits in breeding populations from generation to generation in response to ecological opportunities. The change in the frequency of the hereditary traits occurs through natural selection, genetic drift, and some other mechanisms. The change in the character of hereditary traits occurs through random mutations, mutations that cause deleterious, neutral or beneficial alterations to the alleles. Natural selection is the differential success of individuals to survive and breed against the background of the changing ecological opportunities: what is fit (all green) in one ecology (all green) many not be fit (all green) in a different ecology (mixed green and orange).
Evolution predicts that either:
(a) the selection pressure will cause the all green frogs to go extinct, or
(b) the selection pressure will still allow all green frogs to survive, but in reduced numbers compared to the all green environment, or
(c) a mutation will arise that enable the frogs with the mutation to survive and breed better than their all green cousins, or
(d) a population of frogs from the same source as the orange vegetation would invade the ecology and become predominate due to their previous adaptation to the orange vegetation (their expansion into this area being previously prevented by the all green frogs being better adapted to the all green ecology).
Note that (c) can occur after (b) or during the time it is taking for (a) to occur, as neither would be likely to occur overnight.
The mutation could be for brown or dark skin to blend into shadows, the mutation could be for the frogs to become nocturnal and spend days in hiding, the mutation could be for the frog to become poisonous to the predator, or the mutation could be for colored spots that appear to the predator as similar to the orange/green ecology.
Note that there are frogs that exhibit each of these traits.
Evolution further predicts that, should a beneficial mutation occur, that the distribution of it within the population will be according to common ancestry from the frog with the initial mutation/s.

Creation

As far as I know, the various concepts of creation are that organisms are created as they are. If we consider that this creation is ongoing, then we have concerns about why it wasn't finished and why such changes keep happening. This seems to fall in the "Intelligent Design" concept of an ongoing process.
The major problem is that this concept makes no predictions about changes to any organisms, rather it predicts a lack of change (or the initial product was imperfect).
There is no reason for the frogs to change.

Intelligent Design

If such changes as the (all green) ecology to the (mixed green & orange) ecology were done as part of some intelligent grand scheme, and the changes to the frogs to be orange speckled were also part of that same grand scheme, then we would expect that the changes would occur randomly across the populations of both plant and frog with no hereditary relationship.
If the frogs were "redesigned" for the altered ecology, then the changes should be across the board in the whole frog population, and should result in the best possible fitness to the ecology.
There is no reason for the changes to the frog population to lag behind the changes to the ecology.
Message 8 2. If orange speckling, by chance, occurs due to a single mutation on a single frog, will it be capable of making this the dominant trait of the colony over time? Is this how evolution works? I mean by the chance mutation of a favourable trait on a single organism?
Yes ... IF (a) the selection pressure does not cause extinction first and (b) if the selection pressure is sever enough to depress the reproduction and survival of the all green frogs relative to ones with any orange speckling.
If half the offspring of the initial frog have orange speckling and half of the remaining offspring are subject to predation, then after one generation of frogs there would be twice the number of orange speckled frogs than all green frogs from that one individual.
Also look at the Peppered Moth changes in response to altered ecology.
Peppered Moths and Natural Selection
Enjoy.
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we are limited in our ability to understand
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Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
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This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 32 of 104 (564013)
06-07-2010 7:03 PM
Reply to: Message 30 by Europa
06-07-2010 5:55 PM


Re: Drift And Selection
Hi Europa,
Why would there be any exceptions to blind selection?
Natural selection is blind with no direction or purpose. So the exceptions have direction and purpose?
Selection is not blind, it is a filter.
Organisms that survive better and reproduce better than their peers will produce more offspring which ends up selecting the features that enable them to survive better and reproduce better.
When the ecology is stable this will result in selection for stability, and the only changes will be due to genetic drift.
The modern coelacanthe is larger and lives in a different ecology than the fossil ones, so there has been evolution from the fossils to the modern fish.
Same for alligators and other examples of species that appear in general to be similar to fossil species.
My question is coelacanth is not the only species that live in deep water. If the other species have changed, why has it not changed?
The modern coelacanths do not appear to be a deep water fish, so much as a bottom feeding fish that happens to inhabit the deep water around sea mounts. There are different species found at different sea mounts, rather than one species found in general deep water locations.
Excellent website on the coelacanth
http://www.dinofish.com/
DINOFISH.COM - Weird Bodies Frozen in Time
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.


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This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 43 of 104 (564088)
06-08-2010 7:16 AM
Reply to: Message 41 by Europa
06-08-2010 7:02 AM


Hi Europa,
They both mutate. Its not that the LFs have a low incidence of mutations.
I would think they should both show similar degrees of evolution.
They do, it's just that your expectations of what you should see are incorrect.
But we know they don't. So ...
Random mutations and natural selection after all do not adequately explain evolution?
The reason that "living fossil" appear not very changed is that natural selection kept them in a fit ecology.
If they were not fit they would be extinct eh?
Mutations arise randomly and offer opportunities for change.
If an organism is not fit to the ecology and some of the mutations offer better fitness then natural selection will increase their proportion in the population.
If an organism IS fit and the mutations do not add fitness, then they will all be selected against.
Enjoy
Enjoy.

we are limited in our ability to understand
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Rebel American Zen Deist
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This message is a reply to:
 Message 41 by Europa, posted 06-08-2010 7:02 AM Europa has replied

Replies to this message:
 Message 48 by Europa, posted 06-08-2010 7:22 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 52 of 104 (564191)
06-08-2010 9:37 PM
Reply to: Message 48 by Europa
06-08-2010 7:22 PM


Cyanobacteria -- the ultimate "living fossil"?
Hi Europa,
You're trying to think of evolution as a force of nature. It isn't, it is a result of various processes and opportunities.
When we look at Peppered Moths and Galapagos Finches we see evolution -- the change in the frequency of hereditary traits in breeding populations from generation to generation -- and we see that the population swings one way in response to an ecological change and then swing back when the ecology changes back. Why? Because the first population was better fit for the first ecology.
Well, fine.
My question is why the LFs only? And not everything else?
Because every species lives in a different ecology. Different subpopulation of species can live in different ecoclines. This means that different species have different opportunities and thus are affected differently by selection processes.
Let's start with the ultimate "Living Fossil" -- cyanobacteria:
Fossil Record of the Cyanobacteria
quote:
The cyanobacteria have an extensive fossil record. The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated 3.5 billion years old. This may be somewhat surprising, since the oldest rocks are only a little older: 3.8 billion years old!
Cyanobacteria are among the easiest microfossils to recognize. Morphologies in the group have remained much the same for billions of years, and they may leave chemical fossils behind as well, in the form of breakdown products from pigments.
Cyanobacteria - Wikipedia
quote:
Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria (Greek: κυανός (kyans) = blue). They are a significant component of the marine nitrogen cycle and an important primary producer in many areas of the ocean, but are also found in habitats other than the marine environment; in particular cyanobacteria are known to occur in both freshwater,[2] hypersaline inland lakes[3] and in arid areas where they are a major component of biological soil crusts.
Now here we have a bit of a conundrum: we have a fossil organism\species\type that has apparently evolved tremendously - they have apparently evolved into all other forms of life (or certainly a large number of them), AND
we have a fossil organism\species\type that has apparently barely evolved any changes at all from the original ancestral population, AND
they are the same species.
Logically this means that the result is not, cannot be, dependent on the ability of the population of organisms to evolve, but rather on the external factors that affect the opportunities and selection of the populations of organisms for fitness to different ecologies.
Population {A} in ecology {1} has different opportunities for evolving than population {B} in ecology {2} and there will be different selection of the opportunities for fitness provided by the different sets of random mutations in the different populations --- even if they had the same parents.
Going back to the green frogs:
Message 49: Suppose we have 2 identical islands with green frogs.
What I do not understand is if alien plants can invade one island with green frogs and force them to change and ultimately speciate, why would I think the other island with green froggies can be out of reach for such changes?
Both population has the same possibility of evolving traits that would adapt (or preadapt) them to the green\orange ecology BUT:
The population on the green\orange island will have those opportunities for increased fitness to the green\orange ecology selected FOR, while there will be selection AGAINST staying green, resulting in orange speckles or some other adaptation to the different ecology, and ...
... the population on the green\only island will have those opportunities for increased fitness to the green\orange ecology selected AGAINST, while there will be selection FOR staying green ... resulting in no significant change in the green appearance.
You can even have this happen on one island:
Say your invasive orange speckled plant only survives in the upper elevations on the island. The frog population once covered the whole island, and now you have two different ecologies: one similar to the previous ecology for the whole island and one with the new orange speckled plants.
A sub-population of the green frogs can remain the the green\only ecology, while a second sub-population that happens to evolve orange speckles can now take advantage of the orange\green ecology -- an opportunity that is not open to the green only sub-population.
Thus once again you have the apparent conundrum: we have one sub-population that has apparently evolved tremendously - they have apparently evolved into orange speckled frogs, AND
we have a sub-population that has apparently barely evolved any changes at all from the original all green frogs, AND
they are the same species.
Message 47: If it is not a creative force, how do you explain the existence of human beings form something that started as unicellular organisms?
The same way all other species are explained. There is nothing particularly special about human evolution compared to the evolution of any other species, it is the result of the same basic processes.
Evolution is the change in frequency and character of hereditary traits in breeding populations from generation to generation in response to ecological opportunities.
Humans (and many other species) are very badly fit for occupying the ecological niche filled by cyanobacteria, in fact the species best fit for occupying the cyanobacterial niche is cyanobacteria: hence we still have cyanobacteria occupying that niche.
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 ...
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This message is a reply to:
 Message 48 by Europa, posted 06-08-2010 7:22 PM Europa has replied

Replies to this message:
 Message 54 by Dr Jack, posted 06-09-2010 5:22 AM RAZD has replied
 Message 57 by Europa, posted 06-10-2010 6:04 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 55 of 104 (564378)
06-10-2010 7:39 AM
Reply to: Message 54 by Dr Jack
06-09-2010 5:22 AM


Re: Cyanobacteria -- the ultimate "living fossil"?
Hi Mr Jack,
Perhaps. Or perhaps you are confusing the status of modern cyanobacteria with what the status of ancient cyanobacteria would be.
(If you look at the tree here, all the cyanobacteria are grouped between 4 and 5 O'Clock from Gloebacter and Synechococcus. Note how the root for this group nests with others.)
Curiously, you can also make a straight line from original hypothetical ancestor population (at the center) to these modern cyanobacteria, with all else branching off that line.
So it's generally believed that the Archaea/Bacteria split predates the separation of cyanobacteria from other bacteria.
Which would then need to be before 3.5 billion years ago, yet the only evidence is that cyanobacteria existed at that time ... or that the bacteria lineage split off from the cyanobacteria lineage later ...
Enjoy.
Edited by RAZD, : modern

we are limited in our ability to understand
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Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
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This message is a reply to:
 Message 54 by Dr Jack, posted 06-09-2010 5:22 AM Dr Jack has replied

Replies to this message:
 Message 56 by Dr Jack, posted 06-10-2010 7:52 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 81 of 104 (564520)
06-10-2010 7:54 PM
Reply to: Message 56 by Dr Jack
06-10-2010 7:52 AM


Re: Cyanobacteria -- the ultimate "living fossil"?
Hi Mr Jack,
Also the root is not arbitrary. You can't just root a phylogeny anywhere you like.
So logically you start with the oldest known life form. Cyanobacteria.
The fun thing about cladistics is that you can make any one of the ends lie on a straight line from the beginning:
                \
/\
/\ \
/ / \
/ / /\
/ /\ / \
The critical points are the common ancestors for the branches. The oldest common ancestors are highest on the diagram. The oldest known common ancestor for all the cyanobacteria that exist today must logically be the 3.5 billion year old cyanobacteria, rather than suddenly branch off of other lineages at a later date.
Unless you are arguing that modern cyanobacteria are unrelated to the fossil cyanobacteria.
Thus there is a direct lineage from 3.5 billion year old cyanobacteria to modern cyanobacteria.
Logically this means (many) other forms of life have branched off from this lineage rather than the other way around.
(from Tree of life (biology) - Wikipedia)
If you can point to a node as say that THIS divergence occurred at ____ billion years ago, and before that there were no cyanobacteria, then please do so.
The question is how close to the center the ancient cyanobacteria was. As I said:
... they have apparently evolved into all other forms of life (or certainly a large number of them)
How much depends on how close to the center the ancient cyanobacteria was.
Actually there is chemical evidence for Archaea back to 3.8 billion years ago.
There is possible evidence of some kind of life, yes. IIRC you objected to use of this evidence for life on another thread ...
And amusingly, none of your issues affect the argument that cyanobacteria is the oldest living fossil.
Enjoy.
ps - another good source on the tree of life is
Tree of Life Web Project
Life on Earth
quote:
The rooting of the Tree of Life, and the relationships of the major lineages, are controversial. The monophyly of Archaea is uncertain, and recent evidence for ancient lateral transfers of genes indicates that a highly complex model is needed to adequately represent the phylogenetic relationships among the major lineages of Life. We hope to provide a comprehensive discussion of these issues on this page soon. For the time being, please refer to the papers listed in the References section.
And there is also the issue of horizontal gene transfer mucking up the roots ...

we are limited in our ability to understand
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Rebel American Zen Deist
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This message is a reply to:
 Message 56 by Dr Jack, posted 06-10-2010 7:52 AM Dr Jack has replied

Replies to this message:
 Message 91 by Dr Jack, posted 06-11-2010 5:21 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 83 of 104 (564526)
06-10-2010 8:23 PM
Reply to: Message 57 by Europa
06-10-2010 6:04 PM


Re: Cyanobacteria -- the ultimate "living fossil"?
Hi Europa,
Now Huntard will say this is an argument from incredulity. lol
Many people will tell that this is the logical fallacy of the argument from incredulity, because it is, although it is more formally referred to as the No webpage found at provided URL: Argument from Ignorance (argumentum ad ignorantiam)
See
http://onegoodmove.org/fallacy/toc.htm
http://theautonomist.com/aaphp/permanent/fallacies.php
List of fallacies - Wikipedia
for information on logical fallacies.
Curiously, opinions are absolutely impotent at affecting reality in any way.
This is why, when you rely on opinions you end up with logical fallacies and contradictory conclusions.
Such as one population evolving and another one not, and they are from the same species. The opinion that says this cannot happen is obviously false and needs to be discarded.
Logically, it is also difficult o believe that for one population the environment is more or less the same for millions of years.
Part of your problem is that you are focused on environment, while the important factor for selection is the ecology.
Ecology - Wikipedia
quote:
Ecology (from Greek: οἶκος, "house" or "living relations"; -λογία, "study of") is the scientific study of the distributions, abundance, share affects, and relations of organisms and their interactions with each other in a common environment.[1] ... An ecosystem is the unique network of animal and plant species who depends on the other to sustain life. The interactions between and among organisms at every stage of life and death can impact the system. An ecosystem can be a small area or big as the ocean. ....
Environment may or may not be a critical element of the ecology for an organism, it may depend more on it's relationship to other organisms.
A crocodile lies in wait for prey, partially submerged in water, motionless ... in much the manner of ancestors back in the age of dinosaurs. They do this in a number of different environments around the world, but the basic ecological niche is the predator lying in wait for prey, partially submerged in water, motionless ... and they will surivive in any environment where they can do this.
The coelacanth lives around sea mounts in deep water.
Cyanobacteria still live today, much as they did 3.8 billion years ago when the first known evidence of such organisms occurred.
The shark is an apex predator in the oceans around the world, very much like they were 420 million years ago ... before dinosaurs.
The ecological niche remains the same, regardless of changes to the environment.
Message 1: An alien species of plants invades their environment and the environment starts to change. Now, the frogs are no longer camouflaged in this environment. A bit of orange speckling on their green skin will, however, do the job of camouflaging wonderfully.
Here it is the ecology that changes, making the frogs more liable to predation, changing the predator\prey dynamic, while the environment (bushes, ponds, trees, daily climate, etc) essentially stays the same. Because the ecology changed the frogs will either adapt or perish.
Enjoy.
Edited by RAZD, : ecology change at end

we are limited in our ability to understand
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This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 92 of 104 (564883)
06-13-2010 2:01 PM
Reply to: Message 91 by Dr Jack
06-11-2010 5:21 AM


Re: Cyanobacteria -- the ultimate "living fossil"?
Hi Mr. Jack,
Amusing. I notice that you did not provide an answer to this simple request:
quote:
If you can point to a node as say that THIS divergence occurred at ____ billion years ago, and before that there were no cyanobacteria, then please do so.
Do you have any supporting evidence other than some of the earliest fossils being cyanobacteria?
Can you show that it is absolutely impossible for all life to have evolved from cyanobacteria? If you cannot falsify the possibility, then it exists.
No, you apply cladistic principles to produce the most parsimonious tree. Using incredibly scant fossil evidence to imply positioning is unwise.
So you discard the evidence and replace it with hypothetical inventions? Fascinating approach to science.
Curiously, I find that genetic assumptions on when certain divergences occurred are no good if they do not correlate with fossil evidence. In other words, if the divergence occurred after 3.5 billion years ago, then cyanobacteria are the most parsimonious ancestors.
Until you have fossil evidence of other life forms, and can date when they first lived, then you have no means to gauge which came first. It could be A, it could be B ... (or it could be a group of different species), at this point we don't know.
... And the genetic evidence counters your position. ...
Ah yes, the gods of genetic evidence cannot be disobeyed.
Curiously, genetic evidence cannot tell you when species diverged nor what the actual species they diverged from was, only that it was a shared common ancestor at some point in the past.
   \A
\
/\
B'/ \A'
Species A evolved into Species A' and Species B'
     B/
/
/\
B'/ \A'
Or Species B evolved into Species A' and Species B'
The genetic results are the same, based on the information available ... from living species. In neither case can you tell what the common ancestor was (or was not), only that it was a common ancestor and had traits, some of which are common to both daughter populations and some of which are only common with one or the other. The descendants of the daughter populations will also add new traits that are not common with the other daughter population (unless horizontal gene transfer is involved).
(Plus, as noted, we have the problems of the entertwined roots of life: mitochondria and chloroplasts are distinctive elements to most multicellular eukaryotic life, and the genetic evidence is that cyanobacteria contributed to these lineages as well.)
If cyanobacteria were the root, we'd expect to see cyanobacteria interspersed with the other groups. We don't. We see them all group together.
You see the remaining traits of modern cyanobacteria all grouped together. We classify these traits as being ones belonging to cyanobacteria because they the traits that are common to the modern species of cyanobacteria and not to other life forms.
You also see cyanobacteria grouped with other bacteria (etc) based on their shared genes, which come from the common ancestor. How do you know that those traits are not also ancient cyanobacteria traits?
Thus the common ancestor could be a cyanobacteria ... unless you can show some reason why not.
If you can point to a node as say that THIS divergence occurred at ____ billion years ago, and before that there were no cyanobacteria, then please do so.
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.


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This message is a reply to:
 Message 91 by Dr Jack, posted 06-11-2010 5:21 AM Dr Jack has replied

Replies to this message:
 Message 93 by Dr Jack, posted 06-13-2010 3:39 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 94 of 104 (564927)
06-13-2010 6:02 PM
Reply to: Message 93 by Dr Jack
06-13-2010 3:39 PM


Re: Cyanobacteria -- the ultimate "living fossil"?
Hi Mr. Jack,
... And, despite your frothing, ...
ooo ad hominems now?
... you're the one making a positive assertion that everything evolved from cyanobacteria.
Curiously, you are missing something. Fascinatingly I've repeated it to see if you would see it the second time.
quote:
Message 52: Now here we have a bit of a conundrum: we have a fossil organism\species\type that has apparently evolved tremendously - they have apparently evolved into all other forms of life (or certainly a large number of them), ...
I wonder how much you enjoy making mountains out of molehills.
... you're the one making a positive assertion that everything evolved from cyanobacteria.
Actually you have agreed with what I said:
It is possible that all life evolved from cyanobacteria, ...
... OR that the evolution cyanobacteria has resulted in a large part of life as we know it.
There's these things called molecular clocks.
That are absolutely useless in determining dates for when things occurred. The molecular "clocks" are only as good as their calibration to dates provided by fossil evidence.
Not that that's particularly relevant, since what we're talking it is the order of branching, and the status of various clades.
Oh, but it is very relevant to your claim of having genetic evidence that contradicts the possibility of cyanobacteria being a common ancestor.
Genetic "clocks" are relative dating mechanisms that can tell you that A happened before B which happened before C, but not when they actually happened. No better than geological formations can give you relative dates for fossils in different strata.
We also know that the rates of evolution change in different circumstances, and thus we know that any assumption of a steady rate of change is false. All one needs do is compare the different "clocks" in different species to see that they do not produce - cannot produce - a uniform rate of change.
Yeah, your simple branching pictures are cute but have bugger all to do with we're talking about.
Which shows that you missed the point.
quote:
The genetic results are the same, based on the information available ... from living species. In neither case can you tell what the common ancestor was (or was not), only that it was a common ancestor and had traits, some of which are common to both daughter populations and some of which are only common with one or the other. The descendants of the daughter populations will also add new traits that are not common with the other daughter population (unless horizontal gene transfer is involved).
The tree I showed you is based on ribosomal DNA, it is not based on morphological traits.
Curiously, I did not say morphological. It seems you have made another mistake in reading. Nor does this (corrected) statement contradict what I said, quoted again above.
... and the fact that it is more parsimonious with the known evidence to think that the divergence of Archaea and Bacteria predates the emergence of cyanobacteria and, indeed, that the major Bacterial lineages diverged before cyanobacteria emerged.
And you still have not pointed out evidence that shows when this occurred, rather it is all conjectural and hypothetical.
It is also generally considered that there was considerable mixing going on in early unicellular life, with lots of traits being traded back and forth, and there is some disagreement whether archaea are a separate clade (see below).
And this still does not mean that cyanobacteria are not responsible for major portions of life as we know it.
1. Cyanobacteria are not certain to have lived at 3.5 billion years ago, we think they do, because we've found stromatolites and stromatolites are thought to be formed by cyanobacteria but there are no direct trace fossils of cyanobacteria from this time. The earliest definite traces of cyanobacteria are later.
Okaay, then lets say we are talking about "stromatolitia" - ancient organisms that created the stromatolites (mats of organisms periodically buried by sediment, building up layers that fossilized) 3.5 billion years ago - and that we have descendants today that still produce stromatolites in much the same way that these 3.5 billion year old ancestors did.
These modern descendants happen now to be classified as cyanobacteria, because they happen to be ONE descendant branch from the early "stromatolitia" ... but they are still "stromatolitia" (because dogs are still dogs eh?).
Now here we have a bit of a conundrum: we have a fossil organism\species\type that has apparently evolved tremendously - they have apparently evolved into all other forms of life (or certainly a large number of them), AND
we have a fossil organism\species\type that has apparently barely evolved any changes at all from the original ancestral population, AND
they evolved from the same population of organisms.
3. The earliest traces of life we have aren't cyanobacteria, they're Archaea. Now, these aren't solid enough to say for certain that Archaea predate other life, but at least this - unlike your assertion about cyanobacteria - is consistent with information from other sources.
Is it? Or are there some questions involved
quote:
Message 81: ps - another good source on the tree of life is
Tree of Life Web Project
Life on Earth
quote:
The rooting of the Tree of Life, and the relationships of the major lineages, are controversial. The monophyly of Archaea is uncertain, and recent evidence for ancient lateral transfers of genes indicates that a highly complex model is needed to adequately represent the phylogenetic relationships among the major lineages of Life. We hope to provide a comprehensive discussion of these issues on this page soon. For the time being, please refer to the papers listed in the References section.
And there is also the issue of horizontal gene transfer mucking up the roots ...
This means that there is likely NOT a strict lineal line of descent from early organisms to the life we see today, but rather that the lineages likely crossed and crossed again, sharing traits before settling down.
The evidence is that this was going on after 3.5 billion years ago. This also means that any type of organism from that period could be a "father" (donor of genetic material) rather than a "mother" (provides the cellular structure for the offspring of the combined genetic material).
Certainly we do not classify all the plants with chloroplasts as cyanobacteria, even though genetically they nest together.
The question is whether there are other traits that come from cyanobacteria that are not classified as cyanobacterial traits even though the "stromatolitia" may well be the original source.
If A' and B' evolved from B, and C' evolved from C, A' (not cyanobacteria) should be closer to B' (cyanobacteria) than B' is to C' (cyanobacteria). This isn't the case!
Unless A'' etc. descendants diverged more from the ancestral population than the B'' and C'' descendants -- losing cyanobacterial classing traits in the process -- in order to take advantage of a different ecological opportunity.
3. The earliest traces of life we have aren't cyanobacteria, they're Archaea. Now, these aren't solid enough to say for certain that Archaea predate other life, but at least this - unlike your assertion about cyanobacteria - is consistent with information from other sources.
And you call my position speculative.
What you have are chemicals that may (or may not) be from early life forms. It could be evidence of evolving life, agreed, however to classify it as belonging to one form of life over any other, with nothing else to go on than hypothetical constructions, is pure speculation.
http://www.astrobio.net/.../evidence-of-earths-earliest-life
quote:
"We already knew from our earlier work that we had an assemblage of stromatolites that was most plausibly interpreted as a microbial reef built by Early Archean microorganisms," adds Allwood, "but direct evidence of actual microorganisms was lacking in these ancient, altered rocks. There were no microfossils, no organic material, not even any of the microtextural hallmarks typically associated with microbially mediated sedimentary rocks."
So Allwood set about trying to find other types of evidence to test the biological hypothesis. ...
What she saw were "discrete, matlike layers of organic material that contoured the stromatolites from edge to edge, ...
Allwood says she, Grotzinger, and their team have collected enough evidence that it's no longer any "great leap" to accept these stromatolites as biological in origin. "I think the more we dig at these stromatolites, the more evidence we'll find of Early Archean life and the nature of Earth's early ecosystems," she says.
That's pretty strong evidence that the first known life were responsible for the formation of stromatolites.
Enjoy.
Edited by RAZD, : clrty, end added

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.


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This message is a reply to:
 Message 93 by Dr Jack, posted 06-13-2010 3:39 PM Dr Jack has replied

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 98 of 104 (565306)
06-15-2010 11:39 PM
Reply to: Message 97 by Dr Jack
06-15-2010 8:24 AM


Re: Cyanobacteria -- the ultimate "living fossil"?
+----A1
               |
          +----|
          |    |
          |    +----A2
          |
o----c----|
          |
          |
          |    +----C1
          |    |
          +----|
               |
               +----C2
Enjoy
Edited by RAZD, : to match Mr Jack

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.


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This message is a reply to:
 Message 97 by Dr Jack, posted 06-15-2010 8:24 AM Dr Jack has replied

Replies to this message:
 Message 99 by Dr Jack, posted 06-16-2010 4:39 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 101 of 104 (565438)
06-16-2010 7:13 PM
Reply to: Message 99 by Dr Jack
06-16-2010 4:39 AM


Re: Cyanobacteria -- the ultimate "living fossil"?
Hi Mr. Jack, you're still not seeing the whole concept quite right yet.
What we use to differentiate the A lineage from the C lineage are the differences we see now in the descendants.
... it could be that the entire branch of cyanobacteria that diverged into other life completely died out, ...
Or it simple became the branch of life that we define as non-cyanobacteria, based on the differences in traits from the branch that we define as cyanobacteria.
Let's see if I can make it clearer:
+----A'1
               |
          +----|
          |    |
          A    +----A'2
          |
?----B----|
          |
          C    +----C'1
          |    |
          +----|
               |
               +----C'2
Where B is the basal species, responsible for the stromatolite formations, the earliest evidence we have of simple cell type life...
... which you validly point out does not necessarily have to be from what we would classify today as cyanobacteria ...
... and it diverges into two species A and C.
C has some traits in common with B that are not shared with A, and some new traits that are not shared with A or B. C'1 and C'2 are descendant species, with the traits that C does not share with A.
A has some traits in common with B that are not shared with C, and some new traits that are not shared with B or C. A'1 and A'2 are descendant species, with the traits that A does not share with C.
When you do your "most parsimonious" tree constructed from the genetic data you will end up with (surprise) the very same results you keep nattering on about, because what is used to differentiate between the A lineage and the C lineage are the traits that they do not have in common.
To sensibly reject that interpretation you'd need strong evidence, which you don't have.
Or just realize that genetic analysis does not make a complete picture, especially at this 3.5 billion year remove from early life ... life for which we have absolutely no genetic data ... and as a result it is incapable of saying whether the divergence into A and C happened before or after the date of the fossil evidence we have for B.
To sensibly reject that interpretation you'd need strong evidence, which you don't have.
As opposed to no existing evidence for some made up ancestor, and ignoring evidence that B lived 3.5 billion years ago?
This issue is not about the formation of a genetic nested hereditary tree from the data that shows that the A lineage diverged from the C lineage very early in the diversification of life on earth.
The issue is whether this occurred before or after B, and all I'm saying is that we don't know. Genetic information doesn't tell you dates, so it cannot produce the answer, the answer will come from fossil evidence, if evidence becomes available at all.
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 99 by Dr Jack, posted 06-16-2010 4:39 AM Dr Jack has replied

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