What prevents evolution?

[Matt R.]

Magic_Man,
I just thought of something. Look up the organism Wolbachia. It is vastly more complex then a single mutation (it's an entire species of bacteria), but it drastically effects the reproductive capabalities of the host. Much in the same way your example was describing. You may find it interesting.

Edit -- you may need to dig into it a bit more than just the wikipedia article (just checked wiki). The way it effects the reproduction and evolution of the insects it inhabits is pretty intricate. Googling should turn up some nice stuff. Edit #2! -- There are some more detailed links FROM the wiki site. So there you go [img]/images/graemlins/smile.gif[/img].

[Magic_Man]

Thanks, I'll check it out. I realize that my example was pretty complicated, required many specific, complex mutations. I'm no biologist, so I'm really just trying to get a feel for whether something like this is possible for "speciation."

~MagicMan

[Skidoo]

Matt R. (Matter? Feel the science) and Magic_Man (by all means, keep on the magic):

The definition of "species" as an exclusive set whose individuals are fertile amongst themselves is a functional definition for the purposes of this discussion. It is justified insofar as the development of a mutually fertile group A into a mutually fertile group B that is infertile with A is a necessary condition of all proposed processes of natural evolution.

[Magic_Man]

[ QUOTE ]
Matt R. (Matter? Feel the science) and Magic_Man (by all means, keep on the magic):

The definition of "species" as an exclusive set whose individuals are fertile amongst themselves is a functional definition for the purposes of this discussion. It is justified insofar as the development of a mutually fertile group A into a mutually fertile group B that is infertile with A is a necessary condition of all proposed processes of natural evolution.

[/ QUOTE ]

How is it a necessary condition? The OP clearly stated what the "process of natural evolution" is. Allow me to rephrase briefly:

1) Physical characteristics/behaviors are caused by genes.
2) Genes can mutate, causing differing characteristics.
3) Some mutations will increase the ability to pass along more genes.
4) Some mutations will decrease the ability to pass along more genes.

5) Mutations that increase ability to pass along more genes will get passed along more frequently, causing more and more of the same mutation to exist.
6) Likewise, mutations that decrease the ability to pass along more genes won't last long.

7) As time progresses, we see organisms that are more fit at passing along their genes than their ancestors.


Did you see the word "species" in there anywhere?

~MagicMan

[Matt R.]

That sounds right. Just note that ALL members of a single species are not fertile amongst themselves. One member of a species cannot mate with every single other member (heck, just look at the two sexes for proof), and two reproductively viable members of the same species cannot necessarily produce viable offspring with each other. Exactly in the same fundamental way that members of separate species generally cannot produce viable offspring with each other. The only difference is in the degree of genetic difference (and thus the likelihood) of this incompatibility being present.

[arahant]

I think it's cute that you guys are trying to have a debate with Skidoo.

[Matt R.]

Oh yeah. As Magic pointed out, the conditions you stated aren't really necessary for evolution. Evolution occurs within species too... we don't necessarily have to talk about speciation to talk about evolution.

This appears to be a semantic problem though. I think when you say the "presupposed processes of natural evolution" you are talking about evolution giving rise to the diversity of species. Which your conditions are required for.

[Magic_Man]

[ QUOTE ]
Oh yeah. As Magic pointed out, the conditions you stated aren't really necessary for evolution. Evolution occurs within species too... we don't necessarily have to talk about speciation to talk about evolution.

This appears to be a semantic problem though. I think when you say the "presupposed processes of natural evolution" you are talking about evolution giving rise to the diversity of species. Which your conditions are required for.

[/ QUOTE ]

This is an important point. Evolution can explain the rise of diversity of species; however, evolution does not predict it. Evolution would be just as happy with a world-wide orgy. Speciation mostly happens because of isolation, where two groups undergo non-interactive evolution.

~MagicMan

[Skidoo]

[ QUOTE ]
[ QUOTE ]
Matt R. (Matter? Feel the science) and Magic_Man (by all means, keep on the magic):

The definition of "species" as an exclusive set whose individuals are fertile amongst themselves is a functional definition for the purposes of this discussion. It is justified insofar as the development of a mutually fertile group A into a mutually fertile group B that is infertile with A is a necessary condition of all proposed processes of natural evolution.

[/ QUOTE ]

How is it a necessary condition? The OP clearly stated what the "process of natural evolution" is. Allow me to rephrase briefly:

1) Physical characteristics/behaviors are caused by genes.
2) Genes can mutate, causing differing characteristics.
3) Some mutations will increase the ability to pass along more genes.
4) Some mutations will decrease the ability to pass along more genes.

5) Mutations that increase ability to pass along more genes will get passed along more frequently, causing more and more of the same mutation to exist.
6) Likewise, mutations that decrease the ability to pass along more genes won't last long.

7) As time progresses, we see organisms that are more fit at passing along their genes than their ancestors.


Did you see the word "species" in there anywhere?

~MagicMan

[/ QUOTE ]


No, but, if anything, so much the worse for any there there.

Think of it this way: How can "evolution" proceed without an internally fertile group A developing into an internally fertile group B whose members are not fertile with those of group A?

[Magic_Man]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
Matt R. (Matter? Feel the science) and Magic_Man (by all means, keep on the magic):

The definition of "species" as an exclusive set whose individuals are fertile amongst themselves is a functional definition for the purposes of this discussion. It is justified insofar as the development of a mutually fertile group A into a mutually fertile group B that is infertile with A is a necessary condition of all proposed processes of natural evolution.

[/ QUOTE ]

How is it a necessary condition? The OP clearly stated what the "process of natural evolution" is. Allow me to rephrase briefly:

1) Physical characteristics/behaviors are caused by genes.
2) Genes can mutate, causing differing characteristics.
3) Some mutations will increase the ability to pass along more genes.
4) Some mutations will decrease the ability to pass along more genes.

5) Mutations that increase ability to pass along more genes will get passed along more frequently, causing more and more of the same mutation to exist.
6) Likewise, mutations that decrease the ability to pass along more genes won't last long.

7) As time progresses, we see organisms that are more fit at passing along their genes than their ancestors.


Did you see the word "species" in there anywhere?

~MagicMan

[/ QUOTE ]


No, but, if anything, so much the worse for any there there.

Think of it this way: How can "evolution" proceed without an internally fertile group A developing into an internally fertile group B whose members are not fertile with those of group A?

[/ QUOTE ]

[ QUOTE ]
Allow me to rephrase briefly:

1) Physical characteristics/behaviors are caused by genes.
2) Genes can mutate, causing differing characteristics.
3) Some mutations will increase the ability to pass along more genes.
4) Some mutations will decrease the ability to pass along more genes.

5) Mutations that increase ability to pass along more genes will get passed along more frequently, causing more and more of the same mutation to exist.
6) Likewise, mutations that decrease the ability to pass along more genes won't last long.

7) As time progresses, we see organisms that are more fit at passing along their genes than their ancestors.

[/ QUOTE ]

~MagicMan