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Author Topic:   Macro and Micro Evolution
Chiroptera
Member
Posts: 6859
From: Oklahoma
Joined: 09-28-2003
Member Rating: 5.4


Message 16 of 301 (66913)
11-16-2003 6:36 PM
Reply to: Message 14 by Apollyon
11-16-2003 5:57 PM


quote:
"... a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature." (Mayr)

This is, indeed, a common definition of species, and it is commonly used among biologists. However, this definition has several deficiencies:
The main deficiency is that it only applies to sexually reproducing species. Species that reproduce asexually, such as most single celled organisms and some parthogenetic species of lizards, can not be distinguished by this definition (each individual is reproductively isolated).
Also, reproductive isolation is not an either/or thing - there are varying degrees of reproductive isolation; there are examples of different looking "breeds" which nonetheless interbreed readily (like dogs), and examples of populations that interbreed occasionally but rarely, and examples of populations that never, ever interbreed in the wild but can sometimes interbreed in captivity to produce viable, fertile offspring.
Worse, there are examples of ring species such as the herring gull and the Black-backed gull; in Britain they do not interbreed at all, they were considered different species, but as one travels across the arctic to the west, the herring gull readily interbreeds with a population of eastern North America, which interbreeds with a population of western North America, which interbreeds with a population of Siberia, which interbreeds with...the black-backed gull. So, are these one species or two?

The point is that this definition of species, which is usually pretty useful, isn't too useful in certain situations. This is off topic of your post, but I should add that it is an integral part of evolution theory that populations should gradually differentiate and change into two or more species, and so it is a prediction that there should be examples where populations aren't quite different species, yet not quite the same species either. Creationism tries to invoke some sort of evolution like this, mostly to try to explain how so many "kinds' can fit into Noah's ark, but it is added in a rather ad hoc fashion.

quote:
but how a mutation that makes me immune to malaria (which is not heriditary) can allow the emergence of a new reproductively isolated specie.

A mutation occurs in the genome, and so by definition is inheritable. Here is some information on this mutation.

The point is that small changes will add up to big changes - unless there is something to prevent it. Creationists try to say this is impossible either by claiming that beneficial mutations are too rare or by saying that mutations cannot increase "information" (whatever that is) in the genome. The examples I provided show that this is simply false - there is nothing in principle that prevents small changes from eventually adding up to big changes.

And you are right - it would be so nice if we can do all the necessary experiments in the laboratory. But evolution is too long a process - we cannot simply get the kind of significant macro-evolutionary change that creationists insist upon in a short amount of time (like in a human lifetime). The best we can do is show that each of the little pieces of the theory can individually be shown to work, and then hope that it's clear that each of the pieces, together add up to macro-evolution over the long term - unless someone can show why this is not possible.

[This message has been edited by Chiroptera, 11-16-2003]


This message is a reply to:
 Message 14 by Apollyon, posted 11-16-2003 5:57 PM Apollyon has responded

Replies to this message:
 Message 18 by Apollyon, posted 11-16-2003 6:48 PM Chiroptera has responded

Apollyon
Inactive Member


Message 17 of 301 (66916)
11-16-2003 6:40 PM
Reply to: Message 15 by Ooook!
11-16-2003 6:18 PM


quote:
I can see why you pick these particular examples. These steps occurred millions of years ago and took a loooong time to happen, is it any wonder why we don't know how to recreate them?

I agree, it takes a leap of faith to believe in the consistency of macroevolution.

quote:
If you accept that maybe the step between us and apes is not that large and well within the processes of 'micro' evolution,

That, friend, I cannot accept. Apes and humans are relatively different; genotypically and phenotypically. That is why modern evolution was "refined" to believe that apes did not evolve into humans. We're simply too different.

I am humbly trying to understand more about macroevolution. I am no expert on the subject.


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Apollyon
Inactive Member


Message 18 of 301 (66919)
11-16-2003 6:48 PM
Reply to: Message 16 by Chiroptera
11-16-2003 6:36 PM


Thank you for the useful information, Chiroptera.

However, there are still some questions left unanswered. How does the mechanism of 'natural selection' or an accumelation of mutations account for the complementary male and female reproductive organs? I understand the concept of speciation from a same genus, but a lizard acquiring wings is something to speculate.

Any clarifications?


This message is a reply to:
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crashfrog
Inactive Member


Message 19 of 301 (66921)
11-16-2003 6:51 PM
Reply to: Message 10 by Apollyon
11-16-2003 4:39 PM


It would be much more plausible if we were able to take single-cell prokaryotic cell and 'evolve' it into a multi-celled eukaryote.

Would you settle for a single-cell algae evolving into a colonial organism? That's kind of a half-step in between what you're asking for:

quote:
Coloniality in Chlorella vulgaris 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.

I especially like that last sentence. That's a major morphological change to jump into a different family.


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Apollyon
Inactive Member


Message 20 of 301 (66923)
11-16-2003 6:54 PM
Reply to: Message 19 by crashfrog
11-16-2003 6:51 PM


Thank you, Frog. That is helpful.

This message is a reply to:
 Message 19 by crashfrog, posted 11-16-2003 6:51 PM crashfrog has not yet responded

crashfrog
Inactive Member


Message 21 of 301 (66925)
11-16-2003 6:56 PM
Reply to: Message 18 by Apollyon
11-16-2003 6:48 PM


How does the mechanism of 'natural selection' or an accumelation of mutations account for the complementary male and female reproductive organs?

In higher-order animals? It accounts for them because lower-order animals have them too. Sex isn't a recent development.

The idea is that gender starts at the genetic level, in single-cell or colonial organisms. For instance slime molds have some 50 different genders or so.

The difference in sexual morphology is just a natural development from a genetic gender. Also you might be interested to know that there's a species of ungendered snails that both have spiky penis-like structures. To mate two snails will "fence" until one of them is penetrated by the other's implement. At that point it's that snail that will bear the offspring (lay eggs or whatever.)


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crashfrog
Inactive Member


Message 22 of 301 (66926)
11-16-2003 6:57 PM
Reply to: Message 17 by Apollyon
11-16-2003 6:40 PM


I agree, it takes a leap of faith to believe in the consistency of macroevolution.

Nah, more like the recognition of a trend - naturalism has always come up with a better model than supernaturalism; why suppose it'll be any different here?


This message is a reply to:
 Message 17 by Apollyon, posted 11-16-2003 6:40 PM Apollyon has not yet responded

Ooook!
Member (Idle past 4232 days)
Posts: 340
From: London, UK
Joined: 09-29-2003


Message 23 of 301 (66928)
11-16-2003 7:05 PM
Reply to: Message 17 by Apollyon
11-16-2003 6:40 PM


I agree, it takes a leap of faith to believe in the consistency of macroevolution.

Don't confuse leaps of faith with gaps in our knowledge. We don't know HOW it happened, but things like the fossil record and molecular biology show it DID happen. Insert God A into gap B doesn't really work as an argument.

That, friend, I cannot accept. Apes and humans are relatively different; genotypically and phenotypically. That is why modern evolution was "refined" to believe that apes did not evolve into humans. We're simply too different.

Alright then what are these *huge* differences between us and apes? I'm fairly certain that genotypically we are not that different (98% ring any bells). How are we "simply too different" phenotypically?

And as for the idea that evolutionary theory was 'refined' I seem to have missed that piece of news! As far as I'm aware the idea is that Chimps and us shared a common ancestor and further back we both share a common ancestor with Gorillas. How has this been changed?

Don't think I'm being rude by not replying to your next post, I'm off to bed so I will reply tomorrow

edited for comedy cockney typo

[This message has been edited by Ooook!, 11-16-2003]


This message is a reply to:
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Chiroptera
Member
Posts: 6859
From: Oklahoma
Joined: 09-28-2003
Member Rating: 5.4


Message 24 of 301 (66930)
11-16-2003 7:35 PM
Reply to: Message 18 by Apollyon
11-16-2003 6:48 PM


quote:
How does the mechanism of 'natural selection' or an accumelation of mutations account for the complementary male and female reproductive organs?

Sorry, but I tried to do a quick web search, and couldn't find a "nice and pretty" web page - I hope that this is good enough. But there are species, like Chlamydomonas that do not have different sexes (they are single celled, after all), and they do not have distinguished gametes (the cells are the gametes!). For a primitive multicellular example, the same page has the same type of situation for spirogyra.

quote:
a lizard acquiring wings is something to speculate.

As far as the evolution of the wing, the flying squirrel has the "half-a-wing" that creationists insist cannot exist. I can easily imagine a squirrel that is slightly fluffier, so has just a slightly less hard bump from a fall, slowly transforming to the flying squirrel's skin flaps, which can then slowly transform into a true, flapping wing. You don't believe it? I can imagine it in my head. How did it actually occur in the past? I don't know, but I believe the process is possible - I can conjure up a possibility.

Could something similar happen to produce a bird from a dinosaur? How is this for a flying-squirrel type of intermediary?

(Note that I suspect this creature is not an actual ancestor to birds - just an example to show intermediaries are possible!)


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NosyNed
Member
Posts: 8895
From: Canada
Joined: 04-04-2003
Member Rating: 4.3


Message 25 of 301 (66959)
11-16-2003 10:34 PM
Reply to: Message 24 by Chiroptera
11-16-2003 7:35 PM


You know what I was just astonished to find out this last year!! There is a gliding snake!

http://www.flyingsnake.org/

(but it's not all that good at it )

[This message has been edited by NosyNed, 11-16-2003]


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Replies to this message:
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Brad McFall
Member (Idle past 3449 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 26 of 301 (66962)
11-16-2003 11:09 PM
Reply to: Message 25 by NosyNed
11-16-2003 10:34 PM


Figure 8
The interesting thing is that it does a figure 8 as can be seen in the video clips you linked. I had a red racer from the SW USA as a "pet" when I was a teenager (I gave it away when I came to Cornell) and I was going to write a paper on a method of holding this species that is nearly as fast as they come. Unlike some kinds that species does not like to remain motionless and will twist violently if one attempts to restrain it's "forward" motion. But I figureed out that one could "confuse" the snakes 'sense' of equilibrium REALATIVE TO EARTH (or gravity) if one simply moved the snakes body that was not moving in the form of a figure 8. This species with a black head is perfectly "content" to be in ones hands if its body is continually be shaped by the human in to the figure of eight. The flying snake does this on its own. I had pubilsehd a paper on prey handling in the water snake also relevant to isssues having to do with body shaping by snakes as it is generally not thought that snakes will indeed loop their body around prey even if they only do so in order to restrain the motion of something elese it might eat. Instead people think snakes have emotions. I have never felt this to be a possiblity. Gliding is really NOT all that remarkable among the lower vertebrates as many kinds do it. Frogs, Lizards, Snakes it IS somewhat of note that most of the gliding however is DONE in Malysia and tropics. Flying fish are "good at it" either. It is all in how you "expect" the motion to look. There is clearly a misperception here that St.Hillare rasied with respect to monotreme and other lower verts THAT IS NOT GENERALLY TAUGHT and there is a tendency to think that herpetology has not legit focus but this would be wrong.

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 Message 25 by NosyNed, posted 11-16-2003 10:34 PM NosyNed has responded

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NosyNed
Member
Posts: 8895
From: Canada
Joined: 04-04-2003
Member Rating: 4.3


Message 27 of 301 (66967)
11-16-2003 11:43 PM
Reply to: Message 26 by Brad McFall
11-16-2003 11:09 PM


Re: Figure 8
I would strongly disagree if you are saying flying fish are not good at it. But you use a sentance without not and with either on the end so I can't tell.

They are very good at it, at least compared to the snakes and to flying squirrels.


This message is a reply to:
 Message 26 by Brad McFall, posted 11-16-2003 11:09 PM Brad McFall has responded

Replies to this message:
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Brad McFall
Member (Idle past 3449 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 28 of 301 (66969)
11-16-2003 11:50 PM
Reply to: Message 27 by NosyNed
11-16-2003 11:43 PM


Re: Figure 8
good at it with respect to what? learning to move from water to land from land to air??

perhaps I mis understood you instead. Please tell me what you meant by

quote:
(but it's not all that good at it)simley)""
in the post you linked the flying snake link to. Yes I did meam the fish were "not good at it" IN THE SENSE I WAS TRRING TO COMMUNICATE IN THE POST ( the snake's"" perspective" in terms of the factual issue that St. Hilliare rasied that did not go unnoticed by SJ GOULD.

really I thought you said the "snake was not good at it" and now you seem to say an opposite? WHICH IS IT PLEASE??


This message is a reply to:
 Message 27 by NosyNed, posted 11-16-2003 11:43 PM NosyNed has responded

Replies to this message:
 Message 29 by NosyNed, posted 11-16-2003 11:55 PM Brad McFall has responded

NosyNed
Member
Posts: 8895
From: Canada
Joined: 04-04-2003
Member Rating: 4.3


Message 29 of 301 (66970)
11-16-2003 11:55 PM
Reply to: Message 28 by Brad McFall
11-16-2003 11:50 PM


Re: Figure 8
I think(based on videos) the snake is not all that good. The flying fish is.

This message is a reply to:
 Message 28 by Brad McFall, posted 11-16-2003 11:50 PM Brad McFall has responded

Replies to this message:
 Message 30 by Brad McFall, posted 11-17-2003 12:07 AM NosyNed has responded

Brad McFall
Member (Idle past 3449 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 30 of 301 (66973)
11-17-2003 12:07 AM
Reply to: Message 29 by NosyNed
11-16-2003 11:55 PM


Re: Figure 8
That's fine. Then you may indeed be supporting against my explanation or simply you resorted to you own...that herpetology has not a true lineage basis which I assert is mistaken by not following out the perspective that I mentioned in that post which has nothing to do with me or humanity. Gould simply acknowledged an older contraryness but the motion of a flying fish would be like the lizard keratin (which is NOT in the forms such in snakes) having some motion and nothing about the coiling of the vertebrae which you judged. You also mentioned "squirrels" and it is that which threw up the "red flag" for me. You might know this if you thought about the ribs extending through the skin of salamanders and looking at how lizards glide. Meristic variation is rather hard to view in the sense of the biometry of squamate scalation as it seems to me comparison to fish requires. In the fish the same changes"" appear in D'ARcy Thompson transforms of fish body types not the points of tangent reference form subjectivity which insert fins indeed. I hope this clears up my not editing that post with the missing negative.

This message is a reply to:
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