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Author Topic:   Artificial Selection - Is the term simply convenient?
Taq
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Message 16 of 37 (735907)
08-27-2014 5:31 PM
Reply to: Message 15 by Tangle
08-27-2014 5:22 PM


Probably more precise to use the phrase anthropogenic selection when referring to human intervention in the 'natural' selection process.

That is probably the best suggestion so far.

What we create is an environment where the fittest individuals are those that meet human preferences. As long as we select based on phenotype, then we are following natural selection.

Where anthropogenic selection can diverge from natural selection is if we select based on genotype. Natural selection can not "see" gene sequences, so it always selects based on phenotype. This results in interesting adaptations and allows genotype to be independent of phenotype. If humans select based on gene sequence, then we are ending that independent relationship.


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AppleScratch
Junior Member (Idle past 1022 days)
Posts: 9
Joined: 08-26-2014


Message 17 of 37 (735910)
08-27-2014 5:47 PM
Reply to: Message 13 by NosyNed
08-27-2014 5:09 PM


Re: Missing the Real Issue
quote:

IMHO the real point isn't the man as part of nature part though it stems from us poking at things.
"Natural" selection and "Artificial" selection differ in that man is not (or little ) involved in the former and centrally involved in the later. But that isn't the important fundamental difference.

"Natural" selection has no end goal, no foresight, no global picture. Nothing beyond this individual member of a species and it's success or failure.

"Artificial" selection may have a very definite goal (short or long term), it incorporates the whole picture (that may be selecting individuals to increase the diversity of a rare species, e.g.). It may involve selecting for things that aren't part of the environment yet but are expected (e.g., higher heat tolerance of crops).

Yes, it requires us to do this but I don't see that as being the issue. If we were selecting individuals based on a coin flip then our effects may not be different from "artificial" selection even though we would be selecting.


This is something that I considered also, and I do agree with you that it is easy to perceive this difference. Ideas like the ones you posted were the only reason I felt compelled to even bring it up at all.

The lines just get so blurry that it seems like an unscientific concept to my own ways of thinking. You seem to agree with most of what I had read, where deliberate intent or goals for the future are factors in differentiating artificial from natural.

Would humans hunting a predator to extinction be considered Artificial Selection by your definitions? We determine with our foresight that this species poses a threat to our lives, and become a tremendous selective pressure against it.

This example seems more mundane than proactively selecting crop traits that make cultivation easier. I feel less tempted to claim it as special or artificial, but don't know why in any scientifically justifiable way.

I am honestly not trying to be dense I see why it makes discussion easier to have the distinction, I just can't get to any actual basis for it that is consistent, and it becomes interesting to ponder.


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1.61803
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Posts: 2713
From: Lone Star State USA
Joined: 02-19-2004
Member Rating: 2.5


Message 18 of 37 (735911)
08-27-2014 5:47 PM
Reply to: Message 12 by AppleScratch
08-27-2014 5:04 PM


Re: quid es natural?
All I know is someone needed to tell this guy he's doing it wrong!


"You were not there for the beginning. You will not be there for the end. Your knowledge of what is going on can only be superficial and relative" William S. Burroughs

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Minnemooseus
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(2)
Message 19 of 37 (735912)
08-27-2014 5:49 PM
Reply to: Message 10 by Taq
08-27-2014 4:18 PM


Screw up slowly vs screw up fast
I see no reason why 10,000 years of selective breeding (i.e. artificial selection) is less of a problem than 20 years of genetic recombination in a lab.

But I think that if you're doing something with the possibility of leading to an ecological disaster, it would be better to do it slow and careful.

I don't care if a genetically engineered (20 year variety) food turns out to be bad for human consumption. But if a genetically engineered plant turn out to be bad for bees, then you're heading for an ecological disaster.

Moose


Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.

"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham

"The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness." - John Kenneth Galbraith

"Yesterday on Fox News, commentator Glenn Beck said that he believes President Obama is a racist. To be fair, every time you watch Glenn Beck, it does get a little easier to hate white people." - Conan O'Brien

"I know a little about a lot of things, and a lot about a few things, but I'm highly ignorant about everything." - Moose


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Dr Adequate
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Posts: 15950
Joined: 07-20-2006
Member Rating: 4.6


Message 20 of 37 (735916)
08-27-2014 6:05 PM
Reply to: Message 17 by AppleScratch
08-27-2014 5:47 PM


Re: Missing the Real Issue
Would humans hunting a predator to extinction be considered Artificial Selection by your definitions? We determine with our foresight that this species poses a threat to our lives, and become a tremendous selective pressure against it.

This example seems more mundane than proactively selecting crop traits that make cultivation easier. I feel less tempted to claim it as special or artificial, but don't know why in any scientifically justifiable way.

Well in that case we're not selecting which ones to kill and which ones not to kill in order with the intention of producing a new type.


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AppleScratch
Junior Member (Idle past 1022 days)
Posts: 9
Joined: 08-26-2014


Message 21 of 37 (735920)
08-27-2014 6:24 PM
Reply to: Message 20 by Dr Adequate
08-27-2014 6:05 PM


Re: Missing the Real Issue
quote:

Well in that case we're not selecting which ones to kill and which ones not to kill in order with the intention of producing a new type.

I have a herd of sheep, and kill off the wolves in order for my herd to survive. This allows more successful survival of sheep. This provides more food and utility for myself than if I did not kill the wolves.

I have a crop of corn. I kill off the new plants that have smaller kernels. This allows more successful survival of the larger kernels. This provides more food and utility for myself than if I did not kill the smaller kerneled plants.

Is one of these Artificial selection and the other not? Is attempting to produce a new type, rather than prevent an existing type from undue pressure a difference that I don't understand?


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nwr
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Posts: 5533
From: Geneva, Illinois
Joined: 08-08-2005


Message 22 of 37 (735923)
08-27-2014 6:45 PM
Reply to: Message 21 by AppleScratch
08-27-2014 6:24 PM


Re: Missing the Real Issue
I have a herd of sheep, and kill off the wolves in order for my herd to survive. This allows more successful survival of sheep. This provides more food and utility for myself than if I did not kill the wolves.

I have a crop of corn. I kill off the new plants that have smaller kernels. This allows more successful survival of the larger kernels. This provides more food and utility for myself than if I did not kill the smaller kerneled plants.


I expect that opinions will vary on this.

I would say that what you are doing to the wolves counts as natural selection, albeit anthropogenic natural selection. And what you are doing to the corn counts as artificial selection.


Fundamentalism - the anti-American, anti-Christian branch of American Christianity

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Dr Adequate
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Posts: 15950
Joined: 07-20-2006
Member Rating: 4.6


Message 23 of 37 (735927)
08-27-2014 7:14 PM
Reply to: Message 21 by AppleScratch
08-27-2014 6:24 PM


Re: Missing the Real Issue
Well the difference is that what you're doing in the first case, though it's certainly artificial, isn't selection. You're not picking and choosing among the sheep, or among the wolves.
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AppleScratch
Junior Member (Idle past 1022 days)
Posts: 9
Joined: 08-26-2014


Message 24 of 37 (735928)
08-27-2014 8:05 PM
Reply to: Message 23 by Dr Adequate
08-27-2014 7:14 PM


Re: Missing the Real Issue
Can you elaborate?

Is elimination not considered selection against?

How am I not selecting 'for' sheep and 'against' the wolves in this scenario?


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Dr Adequate
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Posts: 15950
Joined: 07-20-2006
Member Rating: 4.6


Message 25 of 37 (735929)
08-27-2014 8:30 PM
Reply to: Message 24 by AppleScratch
08-27-2014 8:05 PM


Re: Missing the Real Issue
Selection, in the biological sense, involves choosing among the members of a population, not between two whole species only distantly related.
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AppleScratch
Junior Member (Idle past 1022 days)
Posts: 9
Joined: 08-26-2014


Message 26 of 37 (735930)
08-27-2014 8:55 PM
Reply to: Message 25 by Dr Adequate
08-27-2014 8:30 PM


Re: Missing the Real Issue
Can you give a full definition of selection as it applies to biological evolution that we can use for this thread?

www.thefreedictionary.com lists it as: A natural or artificial process that favors or induces survival and perpetuation of one kind of organism over others that die or fail to produce offspring.

If there is another one that is more accurate, I'd like to use it instead . I am not formally researching this field so I may have poor word choice and definitions in my brain.


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herebedragons
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Posts: 1413
From: Michigan
Joined: 11-22-2009
Member Rating: 3.0


Message 27 of 37 (735932)
08-27-2014 10:46 PM
Reply to: Message 17 by AppleScratch
08-27-2014 5:47 PM


Re: Missing the Real Issue
Hi AppleScratch and welcome...

I see why it makes discussion easier to have the distinction, I just can't get to any actual basis for it that is consistent, and it becomes interesting to ponder.

Biological systems rarely have clear cut distinctions unless there is some quantitative value by which to distinguish them. So a group of plants with leaves between 2 cm and 5 cm long belong to this species and those with leaves 7 cm to 10 cm belong to another species. There is something we can quantify and measure to assign a distinction. As you can see by the examples you are pondering, the distinction between "natural" and "artificial" selection is not something that can be quantified and so it becomes difficult to nail it down into distinct categories.

As an example, white-tailed deer use their antlers to fight for the right to mate, so those with bigger, stronger racks have better chances to produce offspring, so we would say natural selection favors larger racks. However, hunters tend to shoot those deer with bigger racks, and since we could consider hunters to simply be apex predators, we could also say that natural selection also works against large racks. But, the way hunting seasons are typically scheduled, the mating begins before or very early in the hunting season and even though a particular male may get shot during the season, he may have already impregnated several females.

The confusion comes in because the predator in question is humans, which makes one think that the selection is "artificial." But if you consider that humans are just a predator in a predator / prey relationship, it is pretty much a natural selection system. However (there's that word again that indicates how difficult it is to define distinct categories), selecting an individual based on antler size is hardly a "natural" choice. Deer with large antlers are typically older, wiser, stronger and warier than their younger, smaller racked comrades. Thus selection for rack size is not a choice based on what makes the animal suitable or preferable prey, but on some arbitrary human preference.

So I would suggest that artificial selection is selection that favors or enhances a particular trait regardless of it's potential effect on fitness. These traits are selected for because of their benefit to humans, not because of their benefit to the organism undergoing selection (even though they may, in fact, improve the organisms ability to survive).

I hope this helps some.

HBD


Whoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca

"Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem.

Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.


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AppleScratch
Junior Member (Idle past 1022 days)
Posts: 9
Joined: 08-26-2014


Message 28 of 37 (735933)
08-27-2014 11:12 PM
Reply to: Message 27 by herebedragons
08-27-2014 10:46 PM


Re: Missing the Real Issue
Very helpful, thank you.

I don't really think there is much else to discuss about this one from my end, I thought there might have been more to it that I was just missing.

Thanks for all of the responses!


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Minnemooseus
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From: Duluth, Minnesota, U.S. (West end of Lake Superior)
Joined: 11-11-2001
Member Rating: 5.6


Message 29 of 37 (735934)
08-28-2014 12:00 AM
Reply to: Message 27 by herebedragons
08-27-2014 10:46 PM


Fish "artificial" selection
No references, but a number of years back I heard (public radio, I believe) about an lab experiment designed to mimic the results of commercial fishing (via nets).

In the wild, the larger fish are preferentially caught because the smaller fish get through the nets. So, to mimic this in the lab population, the larger fish were preferentially removed. This resulted in a population evolution resulting in smaller full grown fish.

Moose

Added by edit - What seems to be a related reference:
Evolutionary response to size-selective mortality in an exploited fish population

Abstract:

quote:
Many collapsed fish populations have failed to recover after a decade or more with little fishing. This may reflect evolutionary change in response to the highly selective mortality imposed by fisheries. Recent experimental work has demonstrated a rapid genetic change in growth rate in response to size-selective harvesting of laboratory fish populations. Here, we use a 30-year time-series of back-calculated lengths-at-age to test for a genetic response to size-selective mortality in the wild in a heavily exploited population of Atlantic cod (Gadus morhua). Controlling for the effects of density- and temperature-dependent growth, the change in mean length of 4-year-old cod between offspring and their parental cohorts was positively correlated with the estimated selection differential experienced by the parental cohorts between this age and spawning. This result supports the hypothesis that there have been genetic changes in growth in this population in response to size-selective fishing. Such changes may account for the continued small size-at-age in this population despite good conditions for growth and little fishing for over a decade. This study highlights the need for management regimes that take into account the evolutionary consequences of fishing.

Full article at cite.

Edited by Minnemooseus, : Added by edit.


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Stile
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Posts: 2958
From: Ontario, Canada
Joined: 12-02-2004
Member Rating: 4.5


Message 30 of 37 (735937)
08-28-2014 9:11 AM
Reply to: Message 21 by AppleScratch
08-27-2014 6:24 PM


Re: Missing the Real Issue
AppleScratch writes:

I have a herd of sheep, and kill off the wolves in order for my herd to survive. This allows more successful survival of sheep. This provides more food and utility for myself than if I did not kill the wolves.

My thoughts would be that you are not doing any selection on the sheep. Therefore the sheep are still undergoing natural selection.
Hmmmm... thought about that. Maybe you are doing artificial selection on the sheep too. That is, without any intervention can we safely assume that the wolves would indeed hunt some of the sheep? If so, then you are artificially removing this selective pressure and therefore causing some amount of artificial selection onto the sheep.

You are, however, definitely doing some selection on the wolves... therefore, the wolves are undergoing artificial selection. You are artificially adding a selective pressure on the wolves for them to not eat sheep. Whether that actually has an effect on the wolves' population is another question... but that's irrelevant. You are still causing some artificial selection on the wolves.

I have a crop of corn. I kill off the new plants that have smaller kernels. This allows more successful survival of the larger kernels. This provides more food and utility for myself than if I did not kill the smaller kerneled plants.

I don't see any trick to this one. Seems like simple artificial selection to me. Your interference is adding a selective pressure onto the corn growth.

Is one of these Artificial selection and the other not? Is attempting to produce a new type, rather than prevent an existing type from undue pressure a difference that I don't understand?

Maybe
I'm certainly no biologist and would drop my line of argument if anyone with such authority says otherwise.


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