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Author Topic:   A beginning
ogon
Member (Idle past 6129 days)
Posts: 70
Joined: 05-13-2007


Message 1 of 22 (400970)
05-17-2007 4:08 PM


My understanding of evolution through a limited amount of reading is,
Species have evolved over time to adapt to their particular environment. And the fittest of the species, suited to that environment are more likely to survive and pass on their genes thus shaping that particular species ensuring a maximum chance of survival. Is this correct?

Replies to this message:
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AdminQuetzal
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Message 2 of 22 (400998)
05-17-2007 6:50 PM


Thread moved here from the Proposed New Topics forum.

  
AZPaul3
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Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 3 of 22 (401001)
05-17-2007 7:04 PM
Reply to: Message 1 by ogon
05-17-2007 4:08 PM


A Subtle Opening?
As a general, uncluttered by minute detail, overview, ogon, so far so good. Is there more?

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mark24
Member (Idle past 5195 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 4 of 22 (401006)
05-17-2007 7:43 PM
Reply to: Message 1 by ogon
05-17-2007 4:08 PM


Ogon,
Spot on, if you mean evolution by means of natural selection.
Gene frequency can be affected by random chance as well, especially if selection pressures are low to non-existant.
Mark

There are 10 kinds of people in this world; those that understand binary, & those that don't

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subbie
Member (Idle past 1254 days)
Posts: 3509
Joined: 02-26-2006


Message 5 of 22 (401015)
05-17-2007 8:26 PM
Reply to: Message 1 by ogon
05-17-2007 4:08 PM


You seem to have a good grasp of the opening basics.
The only suggestion I would have, and I'll admit it might be a bit nitpicky, is to stay away from the term "fittest."

Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin
We see monsters where science shows us windmills. -- Phat

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Doddy
Member (Idle past 5909 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 6 of 22 (401029)
05-17-2007 10:20 PM
Reply to: Message 5 by subbie
05-17-2007 8:26 PM


Only around creationists. If you're talking to population geneticists, then use 'fitness' as much as you want.

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subbie
Member (Idle past 1254 days)
Posts: 3509
Joined: 02-26-2006


Message 7 of 22 (401030)
05-17-2007 10:41 PM
Reply to: Message 6 by Doddy
05-17-2007 10:20 PM


I guess part of what I was thinking of was to avoid slipping into the idea that there's some kind of absolute fitness, without taking into account that it must be viewed in terms of fitness for a particular environment. ogon clearly indicated in his summary that he understands that concept, which is why I acknowledged that it's a little nitpicky.

Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin
We see monsters where science shows us windmills. -- Phat

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ogon
Member (Idle past 6129 days)
Posts: 70
Joined: 05-13-2007


Message 8 of 22 (401055)
05-18-2007 2:54 AM
Reply to: Message 7 by subbie
05-17-2007 10:41 PM


I think I understand the fitness bit.
If a bunch of people were dropped on an island it wouldn't have to be the fittest that survived but rather the survivors would be the ones that could adapt and exploit that particular environment. Correct?

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Doddy
Member (Idle past 5909 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 9 of 22 (401057)
05-18-2007 3:12 AM
Reply to: Message 8 by ogon
05-18-2007 2:54 AM


Yes, if you drop them onto an island in Antarctica, different people would survive longer than if the island was located in Indonesia. Thus, fitness is a reflection of the environment.

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ogon
Member (Idle past 6129 days)
Posts: 70
Joined: 05-13-2007


Message 10 of 22 (401059)
05-18-2007 4:02 AM
Reply to: Message 9 by Doddy
05-18-2007 3:12 AM


okay, I'm trying to keep as specifically biological as I can! It's kinda like trying to ride a bike for the first time, the main task being to stay on the thing!
I mentioned genes in my post. These are the little things that determine what species and appearance we are?
When a pair of one species reproduce the offspring adopt genes from both parents? Like mixing 2 colours, red and yellow for instance makes orange. Though orange is a different colour altogether from red and yellow, in appearance one can tell straight away this colour wasn't made from mixing red and blue!
But let's say red and blue do come along and they have purple offspring. Now let's put the orange and purple offspring into an environment that is predominantly black.
Along comes the great colour eater looking (it has eyes) for it's next meal. Which offspring is the most likely to be eaten and which offspring is most likely to survive?
The surving offspring would be the one that paves the way for future generations.
Now, do genes deliberately reproduce traits suitable for an environment because of the environment OR is it just that on occassions it just gets it right? So really the development of a species is by chance?
sorry guys, did I fall of the bike??????
ogon

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Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 11 of 22 (401064)
05-18-2007 6:49 AM
Reply to: Message 10 by ogon
05-18-2007 4:02 AM


ogon writes:
Now, do genes deliberately reproduce traits suitable for an environment because of the environment OR is it just that on occassions it just gets it right?
The latter.
So really the development of a species is by chance?
Each generation produces many more offspring than will survive to reproduce and contribute to the next generation. By chance, some offspring are more suited to the environment than others. These better suited offspring will make the larger contributions to the next generation.
--Percy

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Doddy
Member (Idle past 5909 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 12 of 22 (401067)
05-18-2007 8:06 AM
Reply to: Message 10 by ogon
05-18-2007 4:02 AM


ogon writes:
So really the development of a species is by chance?
It has a chance component, but selection acts such that the product (next generation) is not just a random mess of genes. Be careful with the chance words, because so often people misunderstand evolution by assuming it's "just random".

Help inform the masses - contribute to the EvoWiki today!
Contributors needed for the following articles: Pleiotropy, Metabolism, Promoter, Invertebrate, Meiosis, DNA, Transcription, Chromosome, Tetrapod, Fossil, Phenotype, Messenger RNA, Mammals, Appendix , Variation, Selection, Gene, Gametogenesis, Homo erectus and others.
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subbie
Member (Idle past 1254 days)
Posts: 3509
Joined: 02-26-2006


Message 13 of 22 (401074)
05-18-2007 9:47 AM
Reply to: Message 10 by ogon
05-18-2007 4:02 AM


Now, do genes deliberately reproduce traits suitable for an environment because of the environment OR is it just that on occasions it just gets it right? So really the development of a species is by chance?
Imagine a population of small animals with relatively little fur. In that population, there will naturally be some variation in the exact amount of fur that each animal has. If the climate begins to cool, you would expect to find that the average amount of fur on the animals will increase. This is not because the genes in those animals decide that the animals need more fur, it's because, across the population, those animals that have more fur will tend to survive to reproduce better than those with less fur. After many generations, there might be so much more fur that you might not even recognize it as the same animal.
As we understand it, genes don't make any effort to produce the traits that organisms need in order to survive. Instead, the organisms that survive are those whose genes happen to produce the traits that tend to make the organisms more likely to successfully compete.
You seem to be still quite comfortably astride your bike and learning the terrain.

Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin
We see monsters where science shows us windmills. -- Phat

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 14 of 22 (401090)
05-18-2007 11:07 AM
Reply to: Message 10 by ogon
05-18-2007 4:02 AM


Very Close Indeed
You have a good handle on the basics, ogon. Be careful of this gene mixing thing. Genes do not blend. They are discrete "packets" with specific functions. It is the "suite" of genes acting in concert that exhibit specific traits.
Eye color is always an excellent example.
There is an Eye Color Gene. Actually, you have two of them. Let's say one is the Brown Eye Allele.
(By the way, an allele is a gene for a specific trait. You have eye color genes. The one gene specific to color brown is the “brown eye allele” version of the eye color gene. You will often hear people speak of genetics and evolution in terms of allele frequency, i.e., the spread of a specific gene (allele/trait) within the larger population.)
Anyway, you may also have a Blue Allele Eye Color Gene. Because of dominant/recessive mechanisms (usually) the brown eye allele will be expressed. The two do not blend together to give you muddy-blue eyes. The blue eye allele will just sorta sit there waiting to see if it gets to be passed on to the next generation where it may be paired up with another blue allele and thus get to be expressed in that individual. That’s kind of what most genes do is hang around to see if anyone will play with them.
Now, in some instances the dominant/recessive mechanisms are not as strict and both alleles will be expressed. The result may appear to be a blending on the larger scale but is in fact the separate expression of each.
ABE: And after a quick cup of coffee and thinking this thing over I want to emphasize what Subbie said in his response to you because his message is the very crux of the operation of evolution. Genes do not change to fit the environment. The frequency of those alleles that convey an advantage in a given environment tend to increase in a population. If the environment changes, the frequency of the various alleles will change over time. Through mutation, new alleles come into existence to be tested in a population. Over many hundreds of generations the alleles and their frequency will change so much that we may say speciation has occurred. This is evolution.
Edited by AZPaul3, : Blame subie. It's his fault.
Edited by AZPaul3, : Cant spel

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Replies to this message:
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ogon
Member (Idle past 6129 days)
Posts: 70
Joined: 05-13-2007


Message 15 of 22 (401145)
05-18-2007 2:29 PM
Reply to: Message 14 by AZPaul3
05-18-2007 11:07 AM


Re: Very Close Indeed
If some genes lay around long enough do they become useless? do they cease to exist?
ogon

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