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Author Topic:   Can Domestic Selection cause Macroevolution?
EZscience
Member (Idle past 5154 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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 Message 70 by kuresu, posted 04-05-2006 11:20 PM kuresu has not replied

Replies to this message:
 Message 90 by Belfry, posted 04-06-2006 6:58 PM EZscience has replied

  
EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 107 of 157 (301870)
04-07-2006 7:51 AM
Reply to: Message 90 by Belfry
04-06-2006 6:58 PM


Re: Domestication redefines 'fitness' for an organism
Well not to split hairs, but as an ecologist and biologist myself I prefer to see the term 'symbiosis' reserved for obligate mutualisms, like the bacteria inhabiting cockroach guts that enable them to digest cellulose.
I would also take issue with terming 'parasitism' any sort of mutualism or symbiosis - the benefit and flow of resources is clearly in one direction only and and there is highly negative impact in the other.

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 Message 90 by Belfry, posted 04-06-2006 6:58 PM Belfry has replied

Replies to this message:
 Message 111 by Quetzal, posted 04-07-2006 9:12 AM EZscience has replied
 Message 116 by Belfry, posted 04-07-2006 10:14 AM EZscience has replied

  
EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 114 of 157 (301912)
04-07-2006 10:08 AM
Reply to: Message 111 by Quetzal
04-07-2006 9:12 AM


Re: Domestication redefines 'fitness' for an organism
quote:
not a biologist although I play one on TV
Cool.
Q writes:
it's often very difficult to tell whether a relationship is mutualistic or comensal - or parasitic.
Yes, I agree there can be a lot of gray areas.
Also most obligate symbioses probably began as parasitic relationships
Q writes:
some Pseudomyrmex species actually "take advantage" of Acacia's pro-ant adaptations without providing any reciprocal benefit.
I know the Pseudomyrmex genus from my work in citrus and I have seen the Acacia system first hand in Mexico. Neat stuff.
My McGraw Hill Dictionary of Sci. and Tech. Terms has two very broad definitions of symbiosis. One actually says 'effects... expressed as harmful or beneficial'. So I'll have to accept parasitism as a form of symbiosis and reliquish my stand on trying to reserve it for exclusively mutually beneficial interactions, although I know it used to be taught this way a long time ago.
Q writes:
while the ants don't defend the tree at all. Just take advantage of the goodies the tree produces. Parasite, mutualist or do we need a new term?
I think this would qualify as 'cleptoparasitism' - an organism stealing resources intended for symbiont. Just like some 'nectar thieves' - insects that bore a hole in the side of the flower to extract nectar from the base, but without providing the pollination service.
This message has been edited by EZscience, 04-07-2006 09:11 AM

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 Message 111 by Quetzal, posted 04-07-2006 9:12 AM Quetzal has replied

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 Message 121 by Quetzal, posted 04-07-2006 12:24 PM EZscience has replied

  
EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 118 of 157 (301922)
04-07-2006 10:34 AM
Reply to: Message 116 by Belfry
04-07-2006 10:14 AM


Changing usage
Yes, that's my impression too.
Sort of an old-school definition I was hanging on to I guess.
(See my capitulation below)
I liked your Rhizobium example.
I work in agriculture, insect ecology and IPM so I like the insect and plant examples also.
The ant-aphid mutualisms are interesting, especially considering certain species of aphid predators and parasities have evolved special adaptations to fool the ants or defend against them, including waxy secretions and chemical camoflage. All so they can get to the aphids that the ants are essentially herding like cows.
I guess (to get this back on topic) one of the ways domestication is most likely to lead to macroevolution is via inadvertant side-effects on the ecology of unrelated organisms.
For example, I study sunflower pests. We have changed the sunflower plant so much in domestication that it has an entirely different community of insects (all native insects, incidentally) boring into it than the wild sunflowers do, even though they are still the same species of plant. We have a longhorned borer that has become a serious pest of cultivated sunflowers and now has even colonized soybeans, and it is now really hard to find this insect in any of its original wild host plants. It is coming to specialize on crop plants exclusively - they are more nutritous and more available. I don't consider it likely to speciate any time soon, but we have inadvertantly created a very different species without necessarily precipitating a speciation event.

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 Message 116 by Belfry, posted 04-07-2006 10:14 AM Belfry has replied

Replies to this message:
 Message 125 by Belfry, posted 04-07-2006 2:29 PM EZscience has replied

  
EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 126 of 157 (302057)
04-07-2006 3:00 PM
Reply to: Message 121 by Quetzal
04-07-2006 12:24 PM


Re: Domestication redefines 'fitness' for an organism
Cleptoparasitism is an accepted term within parasitology.
For example, here is an article about one wasp that follows searching females of another species to steal their hosts.
Q writes:
Most of the places I work don't even have electricity, let alone TV.
(edited to fix link)
I'm betting Guatemala, for one, based on the moniker.
This message has been edited by EZscience, 04-07-2006 02:01 PM
This message has been edited by EZscience, 04-07-2006 02:17 PM

This message is a reply to:
 Message 121 by Quetzal, posted 04-07-2006 12:24 PM Quetzal has replied

Replies to this message:
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EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 128 of 157 (302061)
04-07-2006 3:14 PM
Reply to: Message 125 by Belfry
04-07-2006 2:29 PM


Re: Changing usage
You can see a picture of the insect here and read a recent article about this pest
here
I did a post-doc at U of F for 7 years - did the Cross Florida ride twice. Best time was 7 h, 23 min.
My faculty position kind of killed my cycling 'career', but I hope to revive it. (Picture is from Terrible Two ride, Santa Rosa CA, 2001)

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 Message 125 by Belfry, posted 04-07-2006 2:29 PM Belfry has not replied

  
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