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Evolution and ---cots

Discussion of everything related to the Theory of Evolution.

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Postby ERS » Wed Feb 09, 2005 7:41 pm

praytell, where exactly did you get your version of prehistory??
just curious at this point
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Postby mith » Wed Feb 09, 2005 8:22 pm

Animaniacs :-D.

For the non-cartoon viewers, that's a stupid dumb cartoon show. And yes, I'm obviously kidding.
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Postby RobJim » Wed Feb 09, 2005 10:17 pm

2810713 -

How did scientists conlude that they had common Ncestors ?

Originally it was by observing similarities between the two branches of plants. Remember, all life is hypothesized to have had a common ancestor (or maybe a few of them). Therefore, all plants had a common ancestor at some point. Now, how far back the common ancestor of any two plants was is determined nowadays by comparing the degree of similarity in the genome. If two organisms have the same gene, it generally means they evolved from the same ancestor fairly recently. Before the genomes could be examined directly, scientists looked at morphological similarities and similarities in the biochemistry of the organism.
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sorry

Postby 2810712 » Fri Feb 11, 2005 4:24 am

sorry for such a non-biological activity [ regarding cholesterol].

How did scientists conlude that they had common Ncestors ?

Originally it was by observing similarities between the two branches of plants. Remember, all life is hypothesized to have had a common ancestor (or maybe a few of them). Therefore, all plants had a common ancestor at some point. Now, how far back the common ancestor of any two plants was is determined nowadays by comparing the degree of similarity in the genome. If two organisms have the same gene, it generally means they evolved from the same ancestor fairly recently. Before the genomes could be examined directly, scientists looked at morphological similarities and similarities in the biochemistry of the organism.

- RobJim

OK , but isn't it possible that monocots evolved from a group of dicots which may be existant even today . How did scientists conlude that they had common Ncestors & not evolved from each other ?

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Postby RobJim » Fri Feb 11, 2005 5:14 am

Yes, that's possible. However I guess they assume that over the long period of evolutionary time in which the monocot evolved, there would also be some change in the dicots, even if it's small.

Even if a dicot living today is genetically identical to the one that the monocots evolved from, it is still a descendent of that dicot, and therefore the two plants share a common ancestor.
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Postby keldo » Tue Feb 15, 2005 2:35 am

So back to the first question your saying divergent evolution took place. Kind of like the brown bear diverging into the the polar bear, grizzly bear. But isn't biostudent right by saying that nothing is more evolved then anything else. It just evolves to fit the niches. Basically adaptive radiation. For example if a bacteria did'nt have a niche speaking hypothetically I think it would evolve more and more until it filled a niche. That is also why I think serious forms of macroevolution is not happening now. Humans are in some sorts controlling niches. Think about it. We are intellectually superior to other animals. We control them. If an animal wanders from the place its suppose to be we put it back. Thats why I think animals aren't evolving dirastically. We are making them stay in there certain habitats.
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Postby mith » Tue Feb 15, 2005 3:22 am

They are evolving.
If you subscribe to the theory of punctuated equilibrium, the mutations will accumulate now and suddenly be expressed.
Also we have only been on earth for a couple thousand years. Evolution takes eons to cccur, at least the drastic ones you'd like to see.
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evolving

Postby 2810712 » Tue Feb 15, 2005 4:22 am

They are evolving.
If you subscribe to the theory of punctuated equilibrium, the mutations will accumulate now and suddenly be expressed.
Also we have only been on earth for a couple thousand years. Evolution takes eons to cccur, at least the drastic ones you'd like to see.


I agree mithrilhack.But aren't some of them [mutations] being exposed even today ?
Such as the delta 32 mutation- its presence inhibits the entry of HIV and the in the cells.

And by saying more or less evolved we can compare either the duration of the evolution of two organisms i.e. who originated first or the number of stages of evolution they have undergone till today i.e. no. of evolutionary changes or who is better adapted [' more no. of evolutionary changes' doesn't mean 'better adapted']

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