Can dog breeding truly be considered evolution?

[111111]

I want to clairfy something: Is it true that without DNA mutations it would be impossible to start with a population of x wild wolfs and breed a chihuahua, or poodle?

Lets say your only goal is to start with a very large population of wolfs who on average weigh 100 lbs, your goal is to create a dog that has an adult weight of 5 lbs, and let's say you are controling the evironment ect, so that no DNA mutations would occur. Would it be impossible to create a dog of that size unless you started out with a dog that size?

Assuming no mutations if you start with a trillion wolfs and divide the population into a billion groups of 1000 and breed the smallest male and female from each group and they had 10 puppies each and you continued this until you were down to a final group siblings of puppies with the same parents is it possible that the smallest wolf could be 5 pounds, even though the smallest from the original trillion was say 80 pounds? It seems possible if each generation got smallest size set of contributing genes from each parent. Like if generation 1 got the combination of genes from their parents which is as small as possible, so that if you compare the size contributing genes of the father and mother and pick the ones from each that will contribute most to small size (one parent may be genetically bigger overall but they may have certain genes which contribute more to small size than the other parents versions of those genes).

This would require that the genes for a 5 pound dog were somewhere in that origional population although they may be scattered amongst thousands of dogs.

Is this how dog breeding works, because I find it improbable that enough mutations could have occurred to say create a chihuahua or poodle, in the 10,000 years since dogs first became domesticated by humans.

Another question: is it possilbe for 2 siblings to get an identical set of genes from their parents, without being twins, for example two siblings born years apart which got the same exact genes? Do you know of an example where this has happened?

 

[binzing]

Its chihuahua, sorry, just buggin' me. I would think that it is basically evolution, just a selective form of it.

 

[111111]

There I changed it.

Does anyone who is an expert know the answer to the questions I asked?

 

[_Mayday_]

There I changed it.

Does anyone who is an expert know the answer to the questions I asked?

I would have though an expert on evoltion woul dbe quite hard to come across. I don't think of it as any natural form of evolution, as there is no selection between mates, and they do not evolve to better thei chances of survival.

I think the fact that they are domestic pets would suggest that the evolution you are talking about isn't the same as natural evolution. I myself am not 100% so yes, if there is anyone clued up on this please try an explain :shy:

 

[Andy Resnick]

I don't understand why you exclude mutation from a selection/evolution process. Mutations occur spontaneously all the time, and humans at least have huge numbers of single nucleotide polymorphisms (SNPs). Environmental pressure can drive what mutations are favored, but mutations are not *casued* only by the environment.

 

[_Mayday_]

I don't understand why you exclude mutation from a selection/evolution process. Mutations occur spontaneously all the time, and humans at least have huge numbers of single nucleotide polymorphisms (SNPs). Environmental pressure can drive what mutations are favored, but mutations are not *casued* only by the environment.

Dog breeding is "selective" in most cases. Selective breeding and natural selection are two different things.

 

[Andy Resnick]

Are they? It seems to me that the concept is the same. Certain traits correlate with increased survival and reproduction.

 

[111111]

I don't understand why you exclude mutation from a selection/evolution process. Mutations occur spontaneously all the time, and humans at least have huge numbers of single nucleotide polymorphisms (SNPs). Environmental pressure can drive what mutations are favored, but mutations are not *casued* only by the environment.

The reason I excluded mutations, is because my specific question is how far could an animal be changed with pure breeding. If your goal was to continue to increase a certain trait in an animal how far could that be increased without mutations, and whether their is some limit, and to increase that trait any further you would need mutations. I guess that isn't such an important question anymore, since I would assume that it would be possible, if the original population had the genes somewhere, but it would be extremely unlikely that those genes would all end up in one animal at one point.

By the way you say that mutations happen all the time, are you talking about mutations that get passed down to the child? I always assumed that they were very rare, because otherwise most people would probably have all kinds of genetic problems, since if you pick a random gene which has been chosen by billions of years of trial and error, and change it then you are almost guaranteed to have made a negative change, and only maybe 1 in 10 million DNA mutations would be positive.

And I agree, I think that breeding and natural selection are basically the same, you could see the environment of the domesticated dog as being such that it favored small size. Its still selection for a certain trait, only that trait is chosen by someone.

 

[_Mayday_]

Are they? It seems to me that the concept is the same. Certain traits correlate with increased survival and reproduction.

The dogs aren't being bred to increase their chances of survival! I would agree with you if it occurred naturally but this is dog breeding, it is selective breeing, dogs whos genetics cause then to be better at survival aren't bred with other one as a result of the ones who do not have the survival trait dying.

 

[chroot]

The biological definition of evolution is "the change in alelle frequency with time." This is certainly happening in selectively-bred dogs, and thus it certainly counts as evolution. In this case, the "natural" selection pressures are being overwhelmed by human decision-making, but the biological result is evolution all the same.

- Warren

 

[_Mayday_]

The biological definition of evolution is "the change in alelle frequency with time." This is certainly happening in selectively-bred dogs, and thus it certainly counts as evolution. In this case, the "natural" selection pressures are being overwhelmed by human decision-making, but the biological result is evolution all the same.

- Warren

I am talking about natural evolution. As I am sure you are aware evolution is a pretty vague word, I am saying that in terms of natural evolution where ideas like "survival of the fittest" and "natural selection" come from, this is not what dog breeding is. The reason I say this is that it is human who are controlling it, it is not the surrounding environment that has any say in what happen in terms of how they evolve. The results of this give you two different things, one is adapted to its surrounding environment and it best adapted and the other as you say is being overwhelmed by human decision-making.

 

[chroot]

I am talking about natural evolution. As I am sure you are aware evolution is a pretty vague word, I am saying that in terms of natural evolution where ideas like "survival of the fittest" and "natural selection" come from, this is not what dog breeding is. The reason I say this is that it is human who are controlling it, it is not the surrounding environment that has any say in what happen in terms of how they evolve. The results of this give you two different things, one is adapted to its surrounding environment and it best adapted and the other as you say is being overwhelmed by human decision-making.

There's no sense in trying to isolate "natural" evolution from "artificial" evolution, in the same way that there's no sense in trying to isolate "natural" chemicals from "artificial" chemicals.

Dog breeding is performed by allowing only the best animals to breed. This is still "survival of the fittest," only the assessment of fitness is done by a human being rather than by an ecosystem.

It's still evolution, either way.

- Warren

 

[_Mayday_]

There's no sense in trying to isolate "natural" evolution from "artificial" evolution, in the same way that there's no sense in trying to isolate "natural" chemicals from "artificial" chemicals.

Dog breeding is performed by allowing only the best animals to breed. This is still "survival of the fittest," only the assessment of fitness is done by a human being rather than by an ecosystem.

It's still evolution, either way.

- Warren

This is where I dissagree, dog breeding is performed by allowing only the best animals to breed, that tick the boxes of the dog breeder. An example would be image, or bone structure. These characteristics are not necessarily key in their survival naturally, as their life does not depend on it. I think it is important to isolate both natural evolution and selective evolution, as they are not the same thing. Your example of chemicals does not really have much similarity to the one of dog breeding I don't think.

 

[chroot]

These characteristics are not necessarily key in their survival naturally, as their life does not depend on it.

These characteristics are critical to their ability to reproduce, at least in the false "ecosystem" created by the human breeders. If they escape their pens, all bets are off.

I think it is important to isolate both natural evolution and selective evolution, as they are not the same thing. Your example of chemicals does not really have much similarity to the one of dog breeding I don't think.

You're free to have whatever opinion you like, but the biological definition of evolution is clearly met in both "natural" evolution and in selective breeding. Your personal biases aren't relevant to that determination.

- Warren

 

[_Mayday_]

Dog breeding is "selective" in most cases. Selective breeding and natural selection are two different things.

You're free to have whatever opinion you like, but the biological definition of evolution is clearly met in both "natural" evolution and in selective breeding. Your personal biases aren't relevant to that determination.

- Warren

What I am trying to put forward is that there are two types of selection in evolution that we are talking about. One involves natural selection and the other involves artificial selection. I can accept that the biological definition is that, but I don't see what is wrong with dividing them into atleast these two groups. I am not dissagreeing with the definition, but saying that natural selection is the reproduction of a species with certain traits which is attributed towards its ability to survive and reproduce. Artificial selection is for the good of the human, who intentionally breeds (dogs) seeking particular traits.

I think you have shown that I was initially incorrect in thinking that evolution fitted into more than one category, but I still think that it is important to note that specifically in selection that natural and artificial both result in something different, an adaptation to either their environment or to what their owners seeks to achieve,

 

[chroot]

Again, you're welcome to your opinion -- just don't expect anyone else to have the same opinion.

- Warren

 

[_Mayday_]

Again, you're welcome to your opinion -- just don't expect anyone else to have the same opinion.

- Warren

I don't think you could everyone to have the same opinion on anything, so I wouldn't expect the near on impossible. Thanks for the insight I think I will look at this all in a different light, and maybe I should actually read a bit more into the topic. Thanks.

So I guess getting back to the thread starters question. Yes it is evolution. :tongue:

 

[BoomBoom]

By the way you say that mutations happen all the time, are you talking about mutations that get passed down to the child? I always assumed that they were very rare, because otherwise most people would probably have all kinds of genetic problems,

Yes, mutations happen all the time. If you were to compare any 2 chromosomes, about 1 in every 1,000 bases would be a SNP (Single Nucleotide Polymorphism) on average. Keep in mind though, that the frequency of SNPs are less within genes than they are in between genes due to gene conservation.

Oh and BTW, people DO have all sorts of genetic problems. Many may be obvious, and much more probably not so obvious.

On the subject of dog breeding though, I think dogs have a somewhat unique genome that allows then to vary in size fairly drastically. I would say that the variation we see in dog breeding is more a result of epigenetics, than it is what many of you would think of as "evolution". But then again, IMHO epigenetics is a form of evolution as well...

 

[_Mayday_]

There is nothing sacred about definitions, we can define a word how we like for our own purposes, provided we do so clearly and unambiguously.

 

[skipthecereal]

My 2 cents if you will:
The original question regarding a hypothetical scenario in which you wished to obtain a distinct breed of dog that has a significantly lower average mass than its intial ancestors, without new mutations occurring, is an interesting question.

Firstly though, you simply could not prevent mutations from occurring. Most mutations are the result of infidelities of the DNA copying process. These could not be prevented in large and only enviromental mutation inducing factors could be eliminated, which as we have established play a small part in mutation occurence. Nevertheless it is a hypothetical situation.

Obtaining this distinct breed of lower mass dog without mutations probably wouldn't be possible. Such a drastic difference in average mass would most likely be the result of a number of mutations. But a less drastic result could be attained. Unique combinations of alleles that already exist in the population you see can have massively varying effects depending on what other alleles they find themselves with. Genes do not act singularily and in isolation. The effect of an allele in the phenotype is as much a property of its genetic environment (and for that matter the 'traditional' enviroment) as the protein it codes for (look into additive gene effect). So it is possible that alleles already existing in the population could be combined so a much lighter dog is produced over many generations scrutinised by the human breeder. For as I have alluded to: traits of the phenotype, mass in this instance, are polygenic (determined by a number of genes). Hence there are a suprising number of combinations of genes for a given trait, each producing suprisingly drastic effects.

Hopefully that did not come across as an uninformed rant. As for this debate over what evolution is and whether we can distinguish between natural and artificial selection... I understand evolution as the increasing adaptedness of a population over generations. This may appear to defy the idea that the artificially selected dogs are evolving, but as just stated there is a degree of plasticity in biological 'definitions' which may not be familiar to physical scientists. It could be said the dogs are becoming more adapted, as they are becoming more like what the human breeder wants, and that is their main selection pressure. So I would show little caution in calling both types of selection causing evolution.

The OP asked a second question, regarding the likelyhood of genetically idnetical individuals arising. Possible - yes. Likelyhood - ridiculously unlikely. Let's just consider in short what would have to happen and the approximate probabilities associated with these events. Two identical gametes would have to be produced by two different people: one male one female conventionally. Without going into details this is close to impossible (but technically not). Given this highly unlikely event occurs, the gametes would have to fuse on two occasions. The chance of a particular pair of gametes fusing is another stupidly improbably event. The offspring would also have to be viable (another probability assigned here). These events may as well be assumed independent, so the probability of two identicals being born on different occasions is calculated by mutlipying all these very, very small numbers together; obviously we obtain an even smaller number. Given sufficient time though, even the most improabable event, if it occurs continuously, should occur. But the time required for something like this to happen probably couldn't be counted on two hands. Considerations also have to be given to the different genotypes of individuals and the limited number of copulations in an organisms lifetime. All in all this ain't ever going to happen.

 

[BoomBoom]

I just saw an interesting National Geographic Explorer show on this subject over the weekend. Apparently they have linked the variation in dog size to 1 gene called IGF-1.

I found this NIH press release on this study here: http://www.nih.gov/news/pr/apr2007/nhgri-05.htm"

It seems that just 1 SNP in this gene is enough to account for all the sizes of dogs we see now.

 

[W3pcq]

I am talking about natural evolution.

Evolution is one thing, and survival of the fittest, or natural selection is a cause. Just like human intervention is a cause.

Also why is it always thought that humans are not natural. What we are too smart to be considered natural.

 

[Promethean]

Either way, the work started by Belyaev with foxes and now continued by Trut, showed that domestications brings along an number of phenotypic changes. By using a simple test for tameness, they found that after a number of generations many traits normally associated with domesticated animals spontaneously arose.

Some of these included
f

• loppy ears
• white / black coloration
• pedomorphic traits
• barking
• curly / wavy fur
• long coats / short coats
• reduced tails
• achondrolplasia
• under/over bites

So, the experiment that you are looking for has already been done and the results indicate that is is relatively easy with just a single criteria to produce almost all the traits we see in our modern dog breeds

 

[_Mayday_]

Evolution is one thing, and survival of the fittest, or natural selection is a cause. Just like human intervention is a cause.

Also why is it always thought that humans are not natural. What we are too smart to be considered natural.

Survival of the fittest
Is it that only the fittest digs survive? Or that only the ones best adapted to the Humans taste are bred, this does not lead to the other dogs no surviving? Dogs who fail to comply with the owners needs are not killed, and the breeding is forced on the dog it has no decision in the matter...

I never said humans where not natural, however the process in which the dogs are bred is determined by the owner and not the dogs.

 

[DaveC426913]

Survival of the fittest
Is it that only the fittest digs survive? Or that only the ones best adapted to the Humans taste are bred, this does not lead to the other dogs no surviving? Dogs who fail to comply with the owners needs are not killed, and the breeding is forced on the dog it has no decision in the matter...

I never said humans where not natural, however the process in which the dogs are bred is determined by the owner and not the dogs.

It's not about surviving; it's about breeding.

A dog might breed more because it has better night vision, enabling it to hunt at night.

But a dog might also breed more because it finds itself without a chicken wire fence between it and a potential mate.

In neither case is it the dog's choice or decision.

 

[W3pcq]

Survival of the fittest
Is it that only the fittest digs survive? Or that only the ones best adapted to the Humans taste are bred, this does not lead to the other dogs no surviving? Dogs who fail to comply with the owners needs are not killed, and the breeding is forced on the dog it has no decision in the matter...

I never said humans where not natural, however the process in which the dogs are bred is determined by the owner and not the dogs.

We better get used to considering human intervention as a method of evolution because someday their may be no natural habitat for them to be naturally selected from.

 

[_Mayday_]

It's not about surviving; it's about breeding.

A dog might breed more because it has better night vision, enabling it to hunt at night.

But a dog might also breed more because it finds itself without a chicken wire fence between it and a potential mate.

In neither case is it the dog's choice or decision.

Yeah, Dave I see your point there. I was meaning that two different backgrounds result in two different end products, but that is nothing special, and I am sure that would be obvious to most people, it seemed to slip my mind :shy: I think the real problem here is that I do not have a sound knowledge of evolotion, and probably have a lot of missunderstandings. I think it might be a good idea for me to do a bit more reading. Thanks for putting that into perspective.

 

[Phobos]

Survival of the fittest
Is it that only the fittest digs survive?

In the case of pet dogs, their "ecosystem" testing their fitness is their relationship & cohabitation with humans. (as chroot was saying)
So, the more pleasing a particular variation is to humans, the more that variation will be selected for. (shifting frequency of alleles = evolution)
Note that dogs are a very successful species because they get so much help from humans.

Or that only the ones best adapted to the Humans taste are bred, this does not lead to the other dogs no surviving? Dogs who fail to comply with the owners needs are not killed,

Of course many dogs that are not adopted are put down.
That aside...as someone else said, one of the keys to evolution is leaving more offspring. So the more popular type of dog is selected by humans to produce more offspring.

and the breeding is forced on the dog it has no decision in the matter...I never said humans where not natural, however the process in which the dogs are bred is determined by the owner and not the dogs.

No creature breeds with evolution specifically in mind. They simply breed and gene frequencies shift over time depending on the selective pressures. In the wild, the selective pressures are "natural" and in human control, they're called "artificial". But it's semantics...artificial selection is a subset of natural selection. It can be a useful distinction at times, but people here are just saying that it's all still the same evolution concept.

 

[emr1587]

hi, i just wanted to set a few things right,
"survival of the fittest" has nothing to do with how fit something is, only how many offspring it leaves behind. for example, if an olympic athlet has no children, they have a fitness of 0, they my as well have not been born as evolution see it, but someone who can not run 10 metres but has 20 children is very fit. its all about the number of offspring.

the term is artificial SELECTION or natural SELECTION not artificail evolution, this does not exsist. and it is correct that they do the same thing, they change the FITNESS of individuals. it does not matter if it is the environment of a human taht decides if the dog can breed, it is all selection, the only difference is humans think they are more special than they are, so they get a special term.

ok so the answer to the first question (dog breeding) is yes it is probably possible. there was a study with selective breeding on corn kernal oil which managed to get one strain down to almost no oil in the kernal and another strain to over 100 times the amount of starting oil. this shows the possibilities with selective breeding.
also most of the production animals eg. cows, have been breed in this way, the cow evolved from the auroc (i think that is spelt correctly) which was around twice the size of what we have today. it was transformed to the modern day cow because of selective breeding.

and i do have some idea of what i am talking about, i study genetics at university. and i know i am a bad speller.
(just for nick, you would not say dog breeding is evolution, dog breeding is artificial selection which is a process that causes evolution)

 

[W3pcq]

hi, i just wanted to set a few things right,
"survival of the fittest" has nothing to do with how fit something is, only how many offspring it leaves behind. for example, if an olympic athlet has no children, they have a fitness of 0, they my as well have not been born as evolution see it, but someone who can not run 10 metres but has 20 children is very fit. its all about the number of offspring.

)

True, except that some species have less offspring so that more time can be spent protecting and teaching them, which may actually end up leading to more breading offspring in the end.

I also think that sexual attraction plays a very big often ignored role in evolution. I believe that our brains, particularly females of the human race, have a subconcous domain which makes them attracted to mates for certain reasons depending on the environment that they are living in. A social group develops a system of pride. Things people may take pride in are strength, agility, intelligence, bravery, etc. Maybe one lizard is big and strong, but slow. The female lizard may laugh at the slow lizard, then again maybe she laughs at the fast but less strong lizard. Maybe in an environment that
is requires bulk and brute strength will make the big lizard look attractive to the female? Maybe an environment that requires speed and agility will make a female choose a fast but smaller mate.

If you die, you can't mate. This leads to evolution. However I think that evolution in certain species is driven more by mate selection than by death, and both work together as a team to steer a species in the right direction.

 

[clouded.perception]

As far as the OP goes, the important thing is how closely breeder selection mimicks a pattern of natural selection -- that is, whether creatures are being selected for their genotypes or phenotypes.

For instance, in the early days of cattle breeding (and in most cows today, in fact), breeding was natural selection in all but name -- cows which produced more milk or meat were allowed to breed, gradually resulting in a population that produces more milk or meat. This is a direct, immediate selection due to phenotype, and fits evolution.

But most dogs nowadays are bred with foresight. A dogs will be bred from if there's a good chance that they carry a desired mutation, WHETHER OR NOT THEY EXHIBIT THE MUTATION PHYSICALLY. their partner will be chosen to have the same mutation. this does not mimick natural selection and does not fit the evolution model -- it's similar, but not the same.