Can Domestic Selection cause Macroevolution?

*Words emboldened by me.This thread occurred to me, while reading the Microevolution Vs Macroevolution thread, in which Faith equivocates the mechanisms of Domestic Selection (DS) and Natural Selection (NS) (See above quotes). She further goes on to say that it would seem that if Macroevolution did occur, then one would more likely observe it in DS than in NS; implying that this is proof against Macroevolution.Now, it could be argued that DS is a form of NS (albeit corrupted), in that humans act as the “natural” selecting agent. However, could one say that NS is just DS in nature?
I don’t think so. This goes back to me calling DS corrupted. I say this because that, which is selected for in DS, is what humans regard as desirable; this is not the same as naturally advantageous. For this reason, one would not often find a heavily domesticated animal, surviving, uncared for, in the wild. Maybe I’m out of touch but I still haven’t heard of packs of wild Chihuahuas roaming the Mexican desert . This is not to say that it doesn’t occur, but that it is a rare feat.It is clear, that the outcomes of DS and NS are often at odds with each other. Why is it then that one would expect to observe Macroevolution emerging from DS?
I would actually think it less likely.

I would agree with you here, however, to tie in with the OP, would you say that the oucomes expected of DS are the same as those expected of NS? Is it more likely for DS to show macroevolution than NS?

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"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

I take it that you're saying that in these cases, even though, the great dane and chihuahua are the same species, taxonomically, that there is a "physical" reproductive barrier that could imply biological speciation. Am i right?The thing is, i actually have seen a case where a really small male dog, sired pups of a really big female dog. Don't ask me for refs, since it was a human interest story on the news many years ago. He basically "did his thing" while she was laying down
But that just goes to show that it is possible for these breeds to mate, however rare it might be, reinforcing the taxonomy.I'm not saying that macroevolution could never result from DS (i never say never, anymore), but it is not something one would expect to occur, unlike NS, where one might.It simply sets up a straw man to say that it would be more likely in DS than in NS.
Modulous gave a great account of the main reasons above.

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"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

I would say that speciation is an initialization of Macroevolution.The question would then arise as to whether or not ring species constitute separate species, leading to "what is a species?".
If individuals are theoretically capable of breeding but don't, do they constitute separate species? An argument could be made that they represent variation within a species.If you see my reply to Ramoss, I have seen it happen that a really small dog and a really big dog (don't recall the breeds) were able to sire pups together.I would be willing to say that the possibility of later speciation does exist though, especially when taking WK's post into account.The crux of my question, however (though it may have been badly stated), was whether or not DS represents NS, to the extent that a lack of rapid macroevolution in DS could be used to support the position that macroevolution does not occur via NS?

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"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

Hmmm...I'm sensing a bit of rhetoric here...

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"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

I wrote quite a bit more, but i managed to lose the 1st reply It could be said that variation also includes the genetic diversity already present in a population. As such, DS has been shown to affect it quite drastically. Just look at what monoculture has done to cereals and fruits; their genetic diversity has basically been decimated. This, however, could possibly result in less opportunity for macroevolution. It seems any discussion of Macroevolution, invariably leads down a path of definition; Is it phenotypic change? Is it speciation? Is it more?
Tell me, are all sheep, cattle, goats and pigs each of a single species? Agreed, unfortunately.
Haven't heard of this "new information" concept though.

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"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

I'm pretty happy with that definition, however it is quite worrisome when even university sites are loath to say just that, without other qualifications to it.I agree with you that NS is not the be all and end all of speciation. I'm not about to say, however, that it does not play a possibly significant role.Bringing in things like geographical isolation, etc. just opens a whole other can of worms, that would detract from the crux of the topic.

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"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

Whoa! Didn't expect this topic to blow up overnight.Welcome Faith Glad you could join us. Nothing like a bit of YEC interjection to get the pulses racing on this forum... That's just it tho, Faith. DS is a lot more intense than NS. It is this increase in intensity that would possibly limit its macroevolutionary potential. For macroevolution to occur (and i am using a speciational definition*, will get to this just now), variation (old and new) is required. DS often results in a much faster decrease in variation than NS; so much so that it could restrict the function of variation in speciation.Apart from the above, DS is strongly directed. Humans breed for the characteristics they want. This, added to the weakened effect of variation and drift, could also, intuitively, restrict macroevolution; since humans aren't breeding FOR macroevolution.Then,to bring in a point that Ned raised, macroevolution is not only about Selection. There are other factors involved. Some that, maybe, would lend to DS causing speciation, and some that would take away from this possibility.it should be noted, I'm not saying that speciation is impossible under DS; just that it is, intuitively, less likely.*Speciation in the sense that two different species are genetically incompatible. I do this since there is no reason to set macroevolution at a higher taxonomic level, which are usually just arbitrary anyway.
Fact is, i've noticed that it is often the case that anti-evolutionists get to "set the limits", and evolutionists usually just accomodate them. I don't see why this should be the case, and i tire of it. (Any reply to this particular statement should be taken to the
Microevolution vs Macroevolution thread.

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"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

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': 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.

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"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

Hi Sasquatch, So i take it you're saying that while speciation has not yet occurred, the breeds are morphologically distinct enough to be regarded as on the pathway to speciation, due to physical incompatibility. I've mentioned before that i do accept this as a possibility, however, that incompatibility is not absolute. While it is rare, it is possible for a really small dog to mate with a really big dog; I've seen a case of it.What i'm saying though, is that certain factors of DS make it less conducive to speciation than NS. This however, i've realised, is dependent on the dynamics of specific DS situations. This i hadn't heard of. Is this a by-product of the process, or are they specifically meant to be non-interfertile?

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"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

I think though, that the fact that you still have a bell curve is related to the trait examined (i think you mentioned something about this in your first post). Specifically, it was a quantitative trait that showed the bell curve. I don't expect that this is particularly surprising though, even after a bottleneck.
As an example, my immediate family works pretty well. My father is dark skinned, while my mother is fair skinned. My sisters and i all differ in complexion to both my parents, with one sister sort of olive-skinned, the other, kind of intermediate between my parents, and me being darker than my father. There's a bell curve right there - from the additive combinations of alleles of two individuals.The looked at the variance of non-additive traits as well, and found the reverse of the above, with the broad population showing drastically higher variance.This is not to say that diversity will not recover, but it will not do so quickly, unless re-introduced into the bottlenecked population.The maize example was interesting in that even though there was a strong bottleneck, the extremely high levels of diversity in the ancestral population, allowed enough variation to be carried over into Z. mays. It was not so much that it recovered quickly, but that there was substantial variation to begin with.I'm now more of the mindset that it is more likely isolation that does more to bring about macroevolution, than the actual selective process. Although, high diversity in the ancestral population would not hurt either.You're out of your specialty!? I explicitly opted out of most plant-based courses in undergrad...but i think that had a lot to do with my bias against gardening

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"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

That's interesting. So, i'm guessing this is due to some sort of epistatic or maybe epigenetic effect? This is pretty much what i'm trying to get at. Its not that DS can't cause macroevolution, but that one should not use a lack of clear macroevolution in DS as support against macroevolution occurring in NS.

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"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

Ok...I just got the mental image of a dachsund trying the "splitting of the bamboo" technique I see your point. Although, and i'm going heavily anecdotal here and could be wrong, i'm sure i heard somewhere of female wolves who, when in heat, used to lure dogs into ambush. Herein lies the possibility of hybridisation. I'm basically asking whether the scientists are aiming at non-interfertility, or is it a by-product of the karyotype that they are aiming for?
I expect most of them are induced though. While chromosomal mutations are more common than single base mutations, you'd have to look at the karyotypes of a few thousand mice before you found a natural rearrangement.It can be the case that DS could bring about speciation, however, as you've alluded to, it might often require that the DS is directed toward speciation. Only then, do i feel, it would be more powerful than NS.

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"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

While i did say in an earlier post to Ned, that i didn't see selection as insignificant, i'm not sure that i would go so far as to call it a key to speciation. Although, when it comes to sympatric speciation, i can see how that could be the case. Consider this possibility:
Two founder populations break off from a highly diverse ancestral population; with each accrueing a distinct subset of alleles that differs from the alleles of the other due basically to drift.
Already these populations are genetically distinct. Over enough time, with total isolation, and the accruement of new variation, it should theoretically be possible for speciation to occur. I do agree with you here. Although, the argument over which contributes more to speciation, drift or selection, has not yet been resolved in the scientific community.I would say that it is dependent on whether or not a population is subjected to strong selective pressures. If it is, then selection would be a greater driving force toward speciation. If it isn't, then possibly drift would play a greater role.

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"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

So they're pretty much looking for the karyotype, and then breeding a strain which has that karyotype. This karyotype predisposes to incompatibility; so essentially they are breeding for incompatibility. It might not be their expressed aim, but it is a trait caused specifically by the karyotype they are breeding for.And it goes to what i said at the end of my last post... artificial selection is causing speciation, by being directed to do so.I didn't mean to imply that DS can not cause speciation.

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"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