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Author Topic:   Can Domestic Selection cause Macroevolution?
Wounded King
Member (Idle past 110 days)
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 76 of 157 (301441)
04-06-2006 5:10 AM
Reply to: Message 66 by kuresu
04-05-2006 10:16 PM


I don't think Crash was contradicting himself.
He was making a distinction between parasitism being the same as symbiosis and parasitism being a form of symbiosis. He didn't say it wasn't symbiotic, just that it wasn't the same as symbiosis. He further suggested that describing the symbiotic relationship between humans and maize as parasitic was incorrect and it should more correctly be described as mutualistic.
TTFN,
WK

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Wounded King
Member (Idle past 110 days)
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 77 of 157 (301442)
04-06-2006 5:18 AM
Reply to: Message 57 by Faith
04-05-2006 3:27 PM


Re: It's all word shuffling.
None of these concepts or terms originated as late as the 60's or 70's. I have already suggested when and by who two of the most common definitons of species originated. Do you have anything other than your own subjective opinion to suggest that they werent extant biological terms in the 60's and 70's?
TTFN,
WK

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Belfry
Member (Idle past 5163 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 78 of 157 (301450)
04-06-2006 6:22 AM
Reply to: Message 70 by kuresu
04-05-2006 11:20 PM


kuresu writes:
In ToE, fitness is measured by the number of offspring one has and some other factors dealing with those offspring (if I'm not mistaken). If one has more offspring, the more your genes are present, and if they are beneficial, they will eventually become the dominant phenotype. That is the fitness of NS.
The fitness we look for in crops and animals is not their ability to produce successful offspring, but their ability to provide us with a better yield. This fitness is not the same as that in NS, and therefore DS becomes a corrupted version.
If the crop or animal produce a better yield, then we will encourage their reproduction, meaning that they are more "fit." If an ambrosia beetle's fungus is more nutritious, it will increase the beetle's ability to reproduce and it will be cultivated more. It's still the same thing.

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Belfry
Member (Idle past 5163 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 79 of 157 (301451)
04-06-2006 6:41 AM
Reply to: Message 66 by kuresu
04-05-2006 10:16 PM


A crashfrog said and WK elucidated, symbiosis just means that the relationship exists; the type of relationship (and its relative effect on each organism) is further described as mutualism, commensalism, amensalism, or parasitism. In popular usage, symbiosis=mutualism, but biologists use the term more broadly, because the relationships don't always fall into neat, set categories.
In fact, a mutualistic relationship can even become parasitic, depending on other factors. For example, take the well-known mutualism between nitrogen-fixing Rhizobium bacteria in legume roots. In environments with low available soil nitrogen, the relationship is beneficial to both the host plant (which benefits from the atmospheric nitrogen fixed by the bacterium), and the bacterium (which receives carbohydrates from the plant). If the plant is grown in an environment with high available soil nitrogen, the bacterium becomes unnecessary, and the plant loses carbohydrates to the bacterium without any gain for itself. The bacterium is now a parasite. Thus legumes grown in high-N environments often have fewer (if any) root nodules.
This message has been edited by Belfry, 04-06-2006 06:48 AM
{edit: spelling errors}
This message has been edited by Belfry, 04-06-2006 11:05 PM

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U can call me Cookie
Member (Idle past 5030 days)
Posts: 228
From: jo'burg, RSA
Joined: 11-15-2005


Message 80 of 157 (301503)
04-06-2006 11:08 AM
Reply to: Message 74 by Mammuthus
04-06-2006 4:55 AM


Hi Mammathus,
Thanks for the refs. Managed to find a couple of the papers, and had a quick scan through them.
a few points tho':
So genetic gain in the selected (bottleneck populations) can lead to rapid diversification i.e. potential macroevolution...but the trait being selected is fairly broad as opposed to most DS scenarios..this makes this study a bit more realistic in terms of NS.
I went through the brassica paper and it seems they're not really saying this. The bottlenecked populations showed a short-term increase in additive genetic variance. It took me awhile before I got my head around this concept, but it doesn't really equate with diversity. Basically, it refers to the distribution of variation of quantitative (continuous) traits; pretty much the bell curve, i expect. What the article says is that this additive variance is higher, so it could mean that the bell curve is wider. Overall genetic variance and diversity was still significantly higher in the broad population though, as compared to the bottlenecked populations.
I didn't look at the butterfly paper, but from the abstract, i think it refers to the same thing. I couldn't find a reason for this increase though; maybe if i read through the paper more closely...
Admittedly though, it seems i should take back a generalization i made about DS resulting in much lower variation. In principle, this does occur, however, the amount of diversity that exists after the bottleneck is dependent on what existed in the parent population, and the dynamics of the bottleneck, as was the case with maize. Maize (Z. mays) actually, started out with a substantial amount of diversity, due to the huge amount present in its progenitor. The population size of 20, though, is the effective size, based on a bottleneck of 10 generations; so in actual terms the founder population was much larger than 20.

"The good Christian should beware the mathematician and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of hell." - St. Augustine

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jar
Member
Posts: 34047
From: Texas!!
Joined: 04-20-2004
Member Rating: 5.7


Message 81 of 157 (301511)
04-06-2006 11:16 AM
Reply to: Message 80 by U can call me Cookie
04-06-2006 11:08 AM


couple points to remember
Natural selection is not one single thing. It is as variable as everything else and it includes factors like "Is something else already filling a given niche."
At times the filtering effect might be like a fine mesh net. At other times it might be like a net with a great rip or tear in it that allows large and small to escape.

Aslan is not a Tame Lion

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crashfrog
Member (Idle past 1544 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 82 of 157 (301569)
04-06-2006 1:10 PM
Reply to: Message 66 by kuresu
04-05-2006 10:16 PM


really? you contradict yourself later on
I'm sorry? Where did I contradict myself?
It's no contradiction to say "'doctor' does not mean 'dentist'" and then remind someone that dentists are doctors.
if mutualism is one type of symbiotic relationship, which the defintion you provide earlier does say, then how can you claim that mutualism is not symbiotic, or parasitism for that matter?
I didn't say that mutualism wasn't symbiotic. In fact I said the exact opposite, if you'll read. Mutualistic symbiosis is not the same, however, as parasitic symbiosis. If you had bothered to read my post more carefully you would have seen that I was exactly right in what I said, there's no contradiction at all, because mutualism and parasitism are two different forms of symbiosis. Just because a relationship is symbiotic does not mean it is parasitic; it could be commensurate or mutualist.
I don't know how I could be any clearer than that in two posts. Is English not your first language, or what?

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Faith 
Suspended Member (Idle past 1522 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 83 of 157 (301570)
04-06-2006 1:15 PM
Reply to: Message 77 by Wounded King
04-06-2006 5:18 AM


Re: It's all word shuffling.
None of these concepts or terms originated as late as the 60's or 70's. I have already suggested when and by who two of the most common definitons of species originated. Do you have anything other than your own subjective opinion to suggest that they werent extant biological terms in the 60's and 70's
I'm talking about what I personally encountered that was presented as current thinking. When the new terms originated is an academic point anyway.

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EZscience
Member (Idle past 5231 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 84 of 157 (301579)
04-06-2006 1:35 PM
Reply to: Message 70 by kuresu
04-05-2006 11:20 PM


Domestication redefines 'fitness' for an organism
kuresu writes:
The fitness we look for in crops and animals is not their ability to produce successful offspring, but their ability to provide us with a better yield.
This much is true. Sometimes we actually end up reducing their fitness under NS - meaning we have to supply them with special extra inputs and protection in order to ensure their survival.
Not many crop varieties could surivive in the wild without human support.
In my opinion, domestication is best viewed as a mutualistic relationship (I opt for this instead of 'symbiotic' because the latter strictly implies the relationship is obligatory in both directions - neither can survive without the other).
The selective breeding process simply redefines 'fitness' for the plant or animal, the end result benefiting both humans and the domesticated crop, which thereafter is cared for and its genetic perpetuation virtually assured.
Could selective breeding lead to speciation?
I guess potentially it could, but this has never been a directed goal of breeding animals or plants, nor has it yet been an unintended outcome to my knowledge.

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Admin
Director
Posts: 13081
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.4


Message 85 of 157 (301580)
04-06-2006 1:38 PM
Reply to: Message 82 by crashfrog
04-06-2006 1:10 PM


Forum Guidelines Warning
crashfrog writes:
I don't know how I could be any clearer than that in two posts. Is English not your first language, or what?
Last time I checked the Forum Guidelines were still written in English. I'll withhold any comment about whether you're right or wrong, but I hope you'll agree that the terminology of the topic you're discussing contains the potential for significant confusion. But even if for the sake of argument I agree that you're right and that Kuresu was wrong, that still doesn't entitle you to a "one free jab" card.

--Percy
EvC Forum Director

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Admin
Director
Posts: 13081
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.4


Message 86 of 157 (301582)
04-06-2006 1:41 PM
Reply to: Message 83 by Faith
04-06-2006 1:15 PM


Topic Drift Alert
Wounded King and Faith,
My suggestion is to take the discussion about whether evolutionists are playing a definition shell game to another thread.

--Percy
EvC Forum Director

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kuresu
Member (Idle past 2590 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 87 of 157 (301665)
04-06-2006 3:35 PM
Reply to: Message 82 by crashfrog
04-06-2006 1:10 PM


A
Symbiosis is defined as a relationship between two dissimilar species that is both intimate and potentially obligatory
B
Largely, the contiuum of symbiotic relationships can be described as:
1) Mutualism, where the two organisms each benefit from the relationship;
2) Commensuralism, where one organism benefits and another is not affected;
3) Parasitism, where one organism benefits to the detriment of another
C
Symbiosis is not the same as parasitism
D
could certainly be described as mutualism, and therefore does qualify as a symbiotic relationship
E
I didn't say that mutualism wasn't symbiotic
I hope I don't have to point out the contradiction again. You give a good definition of symbiosis in quote A. You further explain it in quote B, and it is still right. Here comes the contradiction. Look at quote C. How can parasitism not be symbiotic? You include parasitism in your defintion. Look at quote D. You have the same problem. Again, how can mutualism not be symbiotic?
You want to know what's funny. You contradict your contradiction. Quote E is from the post I'm directly replying to. You say that you didn't say what you actually did say. In other words, you said you never said quote D, but you did.
I do agree that parasitism and mutualism are forms of a symbiotic relationship. That is correct.
My correction: You only have one contradiction, not two in yuor original post. So the thrid one doesn't count either. The only contradiction you made is the parasite one. Never mind.
This message has been edited by kuresu, 04-06-2006 03:36 PM

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Modulous
Member
Posts: 7801
From: Manchester, UK
Joined: 05-01-2005


Message 88 of 157 (301720)
04-06-2006 6:01 PM
Reply to: Message 87 by kuresu
04-06-2006 3:35 PM


All fast cars are red, but not all red cars are fast
can parasitism not be symbiotic?
Looks like you got it a bit backwards there. Crashfrog has explicitly said that parasitism is not symbiotic, his quote C says the inverse: Symbiosis is not the same as parasitism.
A simple example shows the error:
We have three types of Car:
1) Nissan
2) Subaru
3) Ford
Ford is a type of car. No doubt about it. However, what crashfrog is saying is that the term 'Car' is not the same as 'Ford'. You are then turning around and saying 'How can you sugges that Fords are not cars?'.
Parasitism is symbiotic.
Symbiotic is not the same as parasitism.
Subsets and supersets and all that jazz.
D and E are not contradictory. Example from above, D is the equivalent of saying 'The Mondeo can be described as being a Ford, therefore it qualifies as being a car'. Quote E is saying "I never said that Fords are not cars". They are not contradictory.

Can we move the discussion forward now?

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pink sasquatch
Member (Idle past 6100 days)
Posts: 1567
Joined: 06-10-2004


Message 89 of 157 (301738)
04-06-2006 6:40 PM
Reply to: Message 1 by U can call me Cookie
04-04-2006 4:03 AM


Yes, methinks.
Hey Cookie.
I've argued before, so I might as well argue now, that dog breeds are a ring species. That is, certain breeds are reproductively isolated from one another (in a pre-mating sense), except for the fact that genetic flow could occur between them using other breeds.
If all domestic dogs except for dachsunds and saint-bernards were wiped off the face of the planet, the remaining dachsunds and saint-bernards would represent two species because of pre-mating reproductive isolation. In absence of human intervention, I don't see the two breeds as being reproductively compatible.
So... this doesn't mean "dog breed speciation" has happened as a result of artificial selection, but I think it shows artificial selection could produce such distinct creatures from a common ancestor as to be morphologically/behaviorally incompatible for reproduction.
Another example that comes to mind is mice that are selected for karyotype abnormalities by genetics laboratories. Mice bred to homozygosity for the novel, "abnormal" karyotype, even though happy, healthy, and fertile, are no longer interfertile with mice with the original "normal" karyotype. It is important to note that these karyotype-level mutational changes do occur naturally, (though they have also been induced). This is an example of artificial selection producing two populations of mice that are post-mating reproductively isolated (speciated) from one ancestor population.

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Belfry
Member (Idle past 5163 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 90 of 157 (301744)
04-06-2006 6:58 PM
Reply to: Message 84 by EZscience
04-06-2006 1:35 PM


Re: Domestication redefines 'fitness' for an organism
EZscience writes:
(I opt for this instead of 'symbiotic' because the latter strictly implies the relationship is obligatory in both directions - neither can survive without the other)
No, not as biologists use the term. As I said before, what you're describing would be called an "obligate mutualism." This is a type of symbiosis, as are parasitism, amensalism, and commensalism.

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