Author Topic: Natural selection  (Read 436 times)

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Offline magicmiles

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Natural selection
« on: March 25, 2012, 10:46:33 PM »
Is this an example of how natural selection works?:

A bird species features some birds with longer beaks than others. In inhabits a certain type of habitat, and then one day a volcanic explosion occurs and the habitat is suddenly much more rocky. This means that the birds with longer beaks are better able to reach insects hidden in the rocks, and they survive longer, breed together and subseqiently more and more birds are born with longer beaks.

Or do I have it completely wrong?
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Offline Omen

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Re: Natural selection
« Reply #1 on: March 25, 2012, 10:52:31 PM »
Living longer is not really relevant, it can be but not necessarily in the description you describe.  The only thing that matters is that the longer beaks promote higher birth rates and there is a population differential over the birds with shorter beaks.

However, selection is not limited to such a singular example, there are actually many types of speciation.
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Offline magicmiles

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Re: Natural selection
« Reply #2 on: March 25, 2012, 11:07:11 PM »
OK thanks.

And is it typically this type of thing which leads to situations where certain traits/characteristics are more readily apparent in a species?
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Offline Omen

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Re: Natural selection
« Reply #3 on: March 25, 2012, 11:11:27 PM »
Another example is called 'ring' evolution.

Imagine a species that exists near a large obstructing geographical feature, as that species flourishes it might gradually spread around the feature ( such as a mountain range or a large body of water ).  As that species spreads around that geographical location it encounters different environment that encourage different variations in its genetic make up as it adapts.  This process continues until the species circles back around to where it first began with one of two results: A. The differences are enough that the original species cannot procreate with the descendants that they encounter. B.  They are genetically similar enough to procreate.

http://en.wikipedia.org/wiki/Ring_species

Gulls are an example as well as salamanders and warblers. ( All in the link )
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Offline Omen

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Re: Natural selection
« Reply #4 on: March 25, 2012, 11:16:02 PM »
OK thanks.

And is it typically this type of thing which leads to situations where certain traits/characteristics are more readily apparent in a species?

No, there are enough variations on selective trait scenario's to not really have a 'typical'. 

Generically we know about allopatric, peripatric, parapatric, and sympatric speciation.  Which encompass speciation for both animals and plants.  There are also other kinds of mutation and certain kinds of genetic drift related to bacteria that are different as well ( like horizontal gene transfer ).

http://en.wikipedia.org/wiki/Speciation#Natural_speciation
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Offline magicmiles

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Re: Natural selection
« Reply #5 on: March 25, 2012, 11:22:12 PM »
Thanks for the explanation.

Sadly my eyes tend to glaze over even with what I assume are very simplistic wiki discussions that you linked to.

I have no under-pinning of science knowledge at all unfortunately. And learning this stuff from scratch is proving time consuming.
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Offline albeto

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Re: Natural selection
« Reply #6 on: March 26, 2012, 12:07:31 AM »
If you haven't already been introduced to it, evolution 101 might be helpful.

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Re: Natural selection
« Reply #7 on: March 26, 2012, 02:11:09 AM »
Sadly my eyes tend to glaze over even with what I assume are very simplistic wiki discussions that you linked to.

I have no under-pinning of science knowledge at all unfortunately. And learning this stuff from scratch is proving time consuming.

If you don't know it, Wikipedia is a very good place to start.
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Offline joebbowers

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Re: Natural selection
« Reply #8 on: March 26, 2012, 03:59:48 AM »
Come on guys let's applaud him for making an effort.

While your example is simplistic, you have the gist of it. At it's essence, it is "survival of the fittest". If you have an advantage, you are more likely to survive and pass on that advantage to your children.

It's interesting to note that it is often the weaker members of a species that must adapt or die. The strong can continue on eating whatever food source they are used to, but the weak get forced out and have to find an alternative. This is likely the reason that humans walk upright. As the lush jungles of the Great Valley Rift[1] began to dry up, and the trees started growing farther and farther apart, the weaker apes[2] were forced to search farther and farther to gather food, and adapted to upright posture and running. The stronger apes didn't have to change.

But eventually as the Rift turned to desert, the upright runner apes could go find a new habitat, but the stronger apes who forced them away eventually died out. Humans are not as strong as many animals, or as fast. Our eyes, noses, and ears are not as keen. Our teeth and claws can't compare to most other species. It's because of these disadvantages that our brains have become so developed.

One could ask, well why didn't we evolve to be stronger or faster or have sharp teeth and long claws instead? We did. All living things on earth share a common ancestor. We are related to bears and snakes and eagles too. Just not as closely or recently as apes.

It amuses me that theists deny evolution yet they still look for an attractive, healthy mate to produce attractive, healthy children.
 1. where early human ancestors came from
 2. Not modern apes, but our common ape-like ancestor. Calling them apes is easier.
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Offline BaalServant

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Re: Natural selection
« Reply #9 on: March 27, 2012, 09:14:51 AM »
Nice question, magicmiles.

Albeto, that evolution 101 link is pretty stinking cool, thanks!
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Offline Tero

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Re: Natural selection
« Reply #10 on: March 27, 2012, 10:51:45 AM »
The Rough Guide to Evolution is very readable.

But there is also some biochemistry and genetics to read. I read those books 20 years till I finally got haploid and diploid. And I've been a chemist 35 years.

Offline nogodsforme

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Re: Natural selection
« Reply #11 on: March 27, 2012, 01:35:56 PM »
I am very haploid with my diploid, thank you.
And magicmiles, good on ya mate for studying up..
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