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Author Topic:   Evolution - recent examples?
crashfrog
Member (Idle past 780 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 16 of 39 (118929)
06-26-2004 1:45 AM
Reply to: Message 15 by tubi417
06-26-2004 12:31 AM


well how would a new species some how be the result of that?

New species ("speciation") result when natural selection operates in a situation of reproductive isolation, where a sub-group is split off from the main population. In this situation, because of the lack of gene flow between groups, the sub-group "drifts" genetically from the original population until cross-breeding ceases to be possible. At that point we have a new species.


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 Message 17 by Wounded King, posted 06-26-2004 3:38 AM crashfrog has replied

  
Wounded King
Member (Idle past 3408 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 17 of 39 (118947)
06-26-2004 3:38 AM
Reply to: Message 16 by crashfrog
06-26-2004 1:45 AM


If its due to drift is it therefore natural selection? Or are you using 'drift' in a different context?

This message is a reply to:
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crashfrog
Member (Idle past 780 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 18 of 39 (118953)
06-26-2004 3:50 AM
Reply to: Message 17 by Wounded King
06-26-2004 3:38 AM


If its due to drift is it therefore natural selection?

As far as I know, genetic drift is not selective. As far as I know, genetic drift is a change in allele frequencies as a result of the randomizing effect of sexual reproduction. The effect on the gene pool is generally less than selection, but in the absence of a selection pressure, sometimes genetic drift alone is enough to cause speciation between two isolated populations.

Oh, wait. I see what you're asking. Yeah, I wasn't referring to genetic drift per se, but rather, the accumulation of genetic differences between gene pools, whatever the cause.

This message has been edited by crashfrog, 06-26-2004 02:51 AM


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Wounded King
Member (Idle past 3408 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 19 of 39 (119395)
06-28-2004 3:26 AM
Reply to: Message 18 by crashfrog
06-26-2004 3:50 AM


But when you use the phrase "'drifts' genetically", you can see where the confusion can arise.

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contracycle
Inactive Member


Message 20 of 39 (119492)
06-28-2004 10:41 AM
Reply to: Message 9 by NosyNed
06-25-2004 12:00 AM


Re: definitly weird
quote:
It sure is a weird way of looking at it.

I don't think its that weird; it is indeed possible for an organism to evolve in a way that makes it overly dependant on a prevailing environmental feature. Arguably, the panda being only sexually receptive 3 days in the year and being dependant on one foodstuff of an example. Fitness in the short term is not always fitness in the long term.

This message has been edited by contracycle, 06-28-2004 09:41 AM


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Brad McFall
Member (Idle past 4346 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 21 of 39 (119495)
06-28-2004 10:55 AM
Reply to: Message 15 by tubi417
06-26-2004 12:31 AM


AAE-no longer dejected
In Princteon Univ Press 2oo#;Niche Construction The Neglected Process in Evolution, Odling-Snee, Laland, and Feldman under the rubric of a concept named, "phenogenotype" write symbols for a general environment/organism interactivity in chapter SIX (not five), "There genotypes and two cultural states can be found in six possible combinations, or phenogenotypes(A more detailed discussion of the phenogenotype concept can be found in chapter 9), namely AAE, AAe, AaE, Aae, aaE, aae, which have fitnesses w_ij (given in table 6.2). We shall use p to denote the frequency of allele A, and x for that of state E."""

I found however, contra the simple attempt in the book to relate this notion to "ecosystem engineering" that bridging the math and the kinematics (involved) remands a JUDGEMENT of Kant's caliber. They did not do this bur relied on psychology and anthropology where I still ONLY find physics and chemistry!!

What IS wierd is that I was told to FIX this psychiatrically where it is clear that no individual human could compelte the populations' task even if it was not artifical but failure to trace the human invetion led to failure to find that other creatures can be deceptive in the same sense that Kant better Hume's journey of cause and effect PAST a river!! So handgernaids and horseshows on are grounded for Bra's behavior@@.


This message is a reply to:
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Steen
Inactive Member


Message 22 of 39 (120207)
06-30-2004 12:45 AM
Reply to: Message 1 by tubi417
06-24-2004 8:52 PM


More example of macro-evolution, of speciation (very detailed, showing exactly what the mutation is):
http://www.nmsr.org/nylon.htm

And a bunch others:
http://www.gate.net/~rwms/EvoMutations.html

Also look at the tread on ring species elsewhere here:
www.evcforum.net/cgi-bin/dm.cgi?action=page&f=5&t=488&p=5 -->www.evcforum.net/cgi-bin/dm.cgi?action=page&f=5&t=488&p=5">http://www.evcforum.net/cgi-bin/dm.cgi?action=page&f=5&t=488&p=5


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RRoman
Inactive Member


Message 23 of 39 (120322)
06-30-2004 9:31 AM


Hi folks, I haven't posted here in a while because I got a bit sick of the evolution/creation debate, but I've just installed the BBCode extension to my firefox browser, and decided to try it out. I also have a blog, Vapid Rants, where I might talk about evolution/creation once in while, I haven't decided yet.

But back to the thread:
A very good example of evolution in the laboratory (at least I think so) is the story of Chlorella vulgaris:

quote:
Predation was a powerful selective force promoting increased morphological complexity in a unicellular prey held in constant environmental conditions. The green alga, Chlorella vulgaris, is a well-studied eukaryote, which has retained its normal unicellular form in cultures in our laboratories for thousands of generations. For the experiments reported here, steady-state unicellular C. vulgaris continuous cultures were inoculated with the predator Ochromonas vallescia, a phagotrophic flagellated protist (’flagellate‘). Within less than 100 generations of the prey, a multicellular Chlorella growth form became dominant in the culture (subsequently repeated in other cultures). The prey Chlorella first formed globose clusters of tens to hundreds of cells. After about 10–20 generations in the presence of the phagotroph, eight-celled colonies predominated. These colonies retained the eight-celled form indefinitely in continuous culture and when plated onto agar. These self-replicating, stable colonies were virtually immune to predation by the flagellate, but small enough that each Chlorella cell was exposed directly to the nutrient medium.

http://www.kluweronline.com/oasis.htm/171545


quote:

Chlorella vulgaris is a common unicellular green alga that is used as a "lab rat" in labs throughout the world. We've grown the same strain of it for thousands of generations on agar and in liquid culture without it losing its unicellular morphology. Dozens to hundreds of labs have done this. Steady-state unicellular C. vulgaris cultures were innoculated with the predator Ochromonas vellesiaca, a phagotrophic flagellate. Within less then 100 generations a multicellular form of the Chlorella became dominanat in the culture. (Boraas 1983b, Boraas et al. 1998). The alga first formed globose clusters of tens to hundreds of cells. After 10-20 generations in the presence of the flagellate, eight-celled colonies predominated. These colonies retained the eight-celled morphology indefinitely in continuous culture and when plated onto agar. The basis of the change appears to be a change in the cell wall. Cell division in normal Chlorella occurs within the cell wall of the maternal cell. The cell undergoes 1-4 divisions to form 2-16 daughter cell. This is followed by a split in the mother cell wall and dispersal of the neonatal cells. In a cuture, empty mother cell walls are interspersed with whole cells at a ratio of about 1:4. Empty mother cell walls are not found in cultures of the multicellular form. The colonies are enclosed in a "membrane" which appears to be modified cell wall material.
As was seen in the bacterial cases, this mutation provided Chlorella with resistance to predation at the cost of growth rate. Neonatal colonies are barely small enough for Ochromonas to engulf. After they have grown slightly they are to big to be eaten. In the presence of the predator, the colonial form of Chlorella displaces the unicellular form and persists. When the predator is not present, the unicellular form displaces the colonial form. This makes sense as the colonial form has less surface area exposed to the environment available for nutrient uptake than the unicellular form has.

http://www.talkorigins.org/faqs/mutations.html


quote:
Boraas (1983) reported the induction of multicellularity in a strain of Chlorella pyrenoidosa (since reclassified as C. vulgaris) by predation. He was growing the unicellular green alga in the first stage of a two stage continuous culture system as for food for a flagellate predator, Ochromonas sp., that was growing in the second stage. Due to the failure of a pump, flagellates washed back into the first stage. Within five days a colonial form of the Chlorella appeared. It rapidly came to dominate the culture. The colony size ranged from 4 cells to 32 cells. Eventually it stabilized at 8 cells. This colonial form has persisted in culture for about a decade. The new form has been keyed out using a number of algal taxonomic keys. They key out now as being in the genus Coelosphaerium, which is in a different family from Chlorella.

http://www.talkorigins.org/faqs/faq-speciation.html



"Knowledge is Power" - Francis Bacon

Replies to this message:
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crashfrog
Member (Idle past 780 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 24 of 39 (120324)
06-30-2004 9:50 AM
Reply to: Message 23 by RRoman
06-30-2004 9:31 AM


Great post, RR. That's one of my favorite examples.

This message is a reply to:
 Message 23 by RRoman, posted 06-30-2004 9:31 AM RRoman has replied

Replies to this message:
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RRoman
Inactive Member


Message 25 of 39 (120854)
07-01-2004 2:43 PM
Reply to: Message 24 by crashfrog
06-30-2004 9:50 AM


Thanks
Thank you for the compliment, Crashfrog. It is also my favorite example, as it shows an entire new family being created, and is thus harder to discount as being an example of macroevolution.


"Knowledge is Power" - Francis Bacon

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Replies to this message:
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Loudmouth
Inactive Member


Message 26 of 39 (120885)
07-01-2004 4:18 PM
Reply to: Message 25 by RRoman
07-01-2004 2:43 PM


Re: Thanks
quote:
It is also my favorite example, as it shows an entire new family being created, and is thus harder to discount as being an example of macroevolution.

It fits within the scientific definition of macroevolution, no doubt there. However, as I am sure you already figured out, it will never be deemed macroevolution among creationists. This is the beauty, if you will, of creationists never defining what constitutes macroevolution. Instead, they apply it in an ad hoc nature which allows them to deny macroevolution no matter what. You would think that a unicellular organism becoming multicellular would be classified as macroevolution, but I would bet that none of the creationist would agree.


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Replies to this message:
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 Message 28 by coffee_addict, posted 07-01-2004 5:39 PM Loudmouth has replied

  
RRoman
Inactive Member


Message 27 of 39 (120917)
07-01-2004 5:16 PM
Reply to: Message 26 by Loudmouth
07-01-2004 4:18 PM


Yeah, I know, they'll either redefine it or simply ignore it, as it always happens in these discussions. That's why I don't participate in evo/cre discussions that much anymore, it's always just a rehash of old fallacies by people who don't even understand evolution (I cringe whenever I hear someone define evolution a la Hovind). The ignorance and stupidy in these arguments just makes me depressed and disgusted, which is why I lost faith in humanity. Well, that and meeting a genuine geocentrist. Never underestimate human stupidity.

This message has been edited by RRoman, 07-01-2004 04:24 PM


"Knowledge is Power" - Francis Bacon

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coffee_addict
Member
Posts: 3645
From: Indianapolis, IN
Joined: 03-29-2004


Message 28 of 39 (120920)
07-01-2004 5:39 PM
Reply to: Message 26 by Loudmouth
07-01-2004 4:18 PM


Re: Thanks
Loudmouth writes:

You would think that a unicellular organism becoming multicellular would be classified as macroevolution, but I would bet that none of the creationist would agree.


You can't really blame them though. Most of them lack the education background to even know the significance and differences between unicellular and multicellular life forms. To the creationists, those little creatures are the same thing as all other microscopic organisms. This is the reason why I have been depressed for the last 3 weeks or so, knowing that there are people that chose to go down the path of ignorance rather than the path of enlightenment.


The Laminator


This message is a reply to:
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Replies to this message:
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Loudmouth
Inactive Member


Message 29 of 39 (120923)
07-01-2004 5:51 PM
Reply to: Message 28 by coffee_addict
07-01-2004 5:39 PM


Re: Thanks
quote:
You can't really blame them though. Most of them lack the education background to even know the significance and differences between unicellular and multicellular life forms.

I can blame them, though. They (creos on debate boards) claim that they have enough scientific knowledge to overturn one of the longest standing and most well supported theories in biology. If they claim to have such an understanding, then they have opened the door for critiques of their understanding and an in-depth criticism of their evidence. They bring this onto themselves by trumpeting their supposed superior reasoning over what they claim are misguided materialistic athiests. Too often they bite off more than they can chew, but that doesn't seem to stop them. Given the average creationists understanding of both scienctific evidence and scientific methodology, I am relieved that creationists make up such a small minority of practicing scientists. Creationists are to science what kindergarten finger painters are to Art.


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 Message 28 by coffee_addict, posted 07-01-2004 5:39 PM coffee_addict has replied

Replies to this message:
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RRoman
Inactive Member


Message 30 of 39 (120947)
07-01-2004 7:15 PM
Reply to: Message 29 by Loudmouth
07-01-2004 5:51 PM


Creationists
quote:
Creationists are to science what kindergarten finger painters are to Art.

Perhaps a more accurate analogy would be that creationists are people who fake money by making color-xeroxes of it (Hovind at al) and the people who gullibly accept that money and are indignant when the money printers tell them that it's not real money.


"Knowledge is Power" - Francis Bacon

This message is a reply to:
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