Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
3 online now:
Newest Member: popoi
Post Volume: Total: 915,819 Year: 3,076/9,624 Month: 921/1,588 Week: 104/223 Day: 2/13 Hour: 1/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Inbreeding VS Evolution
Zealot
Inactive Member


Message 1 of 29 (50574)
08-14-2003 12:41 PM


Hi, on another forum I was on, someone tried to show me that the variety of dogs was a clear indication of evolution.
Seeing as dogs however have been believed to be domesticated from wolves around 20 000 - 30 000 years ago, I find it interesting that they would have shown such tremendous evolutionary change ? From what I gathered, pretty much all dogs in theory can impregnate other dogs, meaning they are the same specie (excuse my leyman!), but if its possibly for dogs to vary so greatly (in such a short period of time) , from great dane to sausage dog (without mutation/evolution), does that not imply that mutation is not neccesary for fossils to vary greatly ?
I mean you could compare the fossils from sausage dogs progressively up to great danes and to the naked eye, it would seem like some sort of evolution has happened ?
Any ideas ?
thanks

Replies to this message:
 Message 2 by Wounded King, posted 08-14-2003 12:48 PM Zealot has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 2 of 29 (50575)
08-14-2003 12:48 PM
Reply to: Message 1 by Zealot
08-14-2003 12:41 PM


What evidence do you have that dogs have undergone no mutation in the course of their selective breeding? It seems much more likely that a number of breeds will have a number of very specific mutations which confer their specific breed traits.
Also the artificial selection used to create new breeds is considerably more extreme than natural selection would be in many environments.
Specie is a type of money, the singular of species is species.

This message is a reply to:
 Message 1 by Zealot, posted 08-14-2003 12:41 PM Zealot has replied

Replies to this message:
 Message 3 by Percy, posted 08-14-2003 1:11 PM Wounded King has replied
 Message 7 by Zealot, posted 08-14-2003 7:59 PM Wounded King has not replied

  
Percy
Member
Posts: 22394
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 3 of 29 (50580)
08-14-2003 1:11 PM
Reply to: Message 2 by Wounded King
08-14-2003 12:48 PM


Wounded King writes:
What evidence do you have that dogs have undergone no mutation in the course of their selective breeding? It seems much more likely that a number of breeds will have a number of very specific mutations which confer their specific breed traits.
Do you really think the different dog breeds are due to mutation events to any significant extent? I've always believed that dog breeding, cat breeding, horse breeding, cattle breeding, any kind of breeding, for the most part merely draw upon existing variation, and that fortuitous mutations are probably rare. Anyone know?
--Percy

This message is a reply to:
 Message 2 by Wounded King, posted 08-14-2003 12:48 PM Wounded King has replied

Replies to this message:
 Message 4 by Dr_Tazimus_maximus, posted 08-14-2003 1:26 PM Percy has not replied
 Message 6 by Wounded King, posted 08-14-2003 7:07 PM Percy has not replied

  
Dr_Tazimus_maximus
Member (Idle past 3217 days)
Posts: 402
From: Gaithersburg, MD, USA
Joined: 03-19-2002


Message 4 of 29 (50584)
08-14-2003 1:26 PM
Reply to: Message 3 by Percy
08-14-2003 1:11 PM


Complex phenotypic blend
The truth will be a bit of a mix IMO. Namely, that breeders selected for the desired traits and that these traits are from a combination of the natural variation from the early population and of more drastic phenotypes from mutations that the breeders have selected for. We may know soon and to what degree if this project works.
------------------
"Chance favors the prepared mind." L. Pasteur
Taz

This message is a reply to:
 Message 3 by Percy, posted 08-14-2003 1:11 PM Percy has not replied

  
Loudmouth
Inactive Member


Message 5 of 29 (50605)
08-14-2003 6:26 PM


Examples of probable mutations have been seen in cats. Hairless cats and cats with extremely short legs have emerged from single sets of parents with no history of such traits. This could still be refuted and may be due to inbreeding, but its still quite a dramatic phenotypic change.
Also, like has been said before, artificial selection has been far greater a pressure than natural selection. I would bet that if all the dogs in the world were set free and allowed to interbreed for a couple of hundred years there would be a very homogenous population, only varying due to geographic isolation.
What say we start a world wide evolution experiment and look for the effects of geographic isolation and genetic drift with domesticated dogs. Seems like a fun little experiment. Go home right now and release Muffy, she is now part of a global experiment. Hehe, a mad scientist is born every minute.

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 6 of 29 (50606)
08-14-2003 7:07 PM
Reply to: Message 3 by Percy
08-14-2003 1:11 PM


Re: yeah.
I think I phrased that badly, I don't think that the original breeding population from which all dogs have been bred were genetically homogeneous to start off with. I am sure there was already a pool of variant alleles, but those alleles themselves would be the product of mutation, and I don't believe that there has been no mutation in canine breeding stock since then.

This message is a reply to:
 Message 3 by Percy, posted 08-14-2003 1:11 PM Percy has not replied

  
Zealot
Inactive Member


Message 7 of 29 (50609)
08-14-2003 7:59 PM
Reply to: Message 2 by Wounded King
08-14-2003 12:48 PM


Inbreeding and fruitfly example
What evidence do you have that dogs have undergone no mutation in the course of their selective breeding? It seems much more likely that a number of breeds will have a number of very specific mutations which confer their specific breed traits.
Also the artificial selection used to create new breeds is considerably more extreme than natural selection would be in many environments.
I have no evidence, merely that I would have assumed it would not be too difficult to detect mutation. I know forinstance that it doesn't take too many generations of cats to produce a cat with certain features (eg: persian cats with flat faces) and I dont think this has anything to do with mutation. For instance, when breeding persians, quite often you find a cat with a longer face, which is often given away for free instead of being sold.
The only reason I asked was that if there really has been no mutations to seperate a St Bernhard from a Pit bull from a Corgie, then it seems to be the same could have happened in other animals forinstace, explaining the differences in fossils. I know this is increased due to inbreeding, however surely with other animals this could have happened, say during a period of famine, a small population of a particular species had to resort to inbreeding, eventually resulting in a different looking species ?
I'm going to take the fruitfly example in comparison here. From what I understand mutations and especially beneficial mutations are excessively rare . Somewhere on this site I read that there have not been any fruitflies that have shown any beneficial mutations. Am I correct is saying it usually renders the organism sterile ? I would have assumed that for so many different types of dogs to be around there would have had to be quite a few mutations ? Yes I realise that an owner would see an unusual looking puppy and might have decided to keep it for asthetic reasons, however usually dogs were bred for a purpose and any dog that didn't fit the mould would have been drowned/killed, or atleast have been prevented from breeding ?
Can anyone tell me, I mean theoretically speaking how many mutations would have occured since dogs were domesticated from wolves ?
thanks for your time.

This message is a reply to:
 Message 2 by Wounded King, posted 08-14-2003 12:48 PM Wounded King has not replied

Replies to this message:
 Message 8 by MrHambre, posted 08-14-2003 8:24 PM Zealot has replied

  
MrHambre
Member (Idle past 1393 days)
Posts: 1495
From: Framingham, MA, USA
Joined: 06-23-2003


Message 8 of 29 (50610)
08-14-2003 8:24 PM
Reply to: Message 7 by Zealot
08-14-2003 7:59 PM


quote:
The only reason I asked was that if there really has been no mutations to seperate a St Bernhard from a Pit bull from a Corgie, then it seems to be the same could have happened in other animals forinstace, explaining the differences in fossils.
Wounded King answered that mutations do in fact account for the differences in traits. Is your point that breeding (or inbreeding) somehow has nothing to do with evolution?
------------------
En la tierra de ciegos, el tuerto es el Rey.

This message is a reply to:
 Message 7 by Zealot, posted 08-14-2003 7:59 PM Zealot has replied

Replies to this message:
 Message 9 by Zealot, posted 08-14-2003 8:34 PM MrHambre has not replied

  
Zealot
Inactive Member


Message 9 of 29 (50613)
08-14-2003 8:34 PM
Reply to: Message 8 by MrHambre
08-14-2003 8:24 PM


Wounded King answered that mutations do in fact account for the differences in traits. Is your point that breeding (or inbreeding) somehow has nothing to do with evolution?
Well yeah. I mean assuming that essentially all dogs would have been domesticated from wolves, inbreeding would explain why there were so many variations in dogs, but not in wolves. Unless ofcourse the differences in dogs were as a result of mutations in the last 30 000 years ? Thats why I want to know how frequently mutations occur in nature and how frequently they are successfull.

This message is a reply to:
 Message 8 by MrHambre, posted 08-14-2003 8:24 PM MrHambre has not replied

Replies to this message:
 Message 10 by crashfrog, posted 08-14-2003 8:46 PM Zealot has replied
 Message 11 by wj, posted 08-14-2003 11:03 PM Zealot has replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 10 of 29 (50616)
08-14-2003 8:46 PM
Reply to: Message 9 by Zealot
08-14-2003 8:34 PM


Thats why I want to know how frequently mutations occur in nature and how frequently they are successfull.
Well, you have somewhere between 4 and 50 mutations, yourself. Do they do anything? Not usually. (Most mutations cause no change because of error correction in the protein synthesis process.)
Do you mean to ask, how often do mutations happen that cause some perceptible change in the phenotype?

This message is a reply to:
 Message 9 by Zealot, posted 08-14-2003 8:34 PM Zealot has replied

Replies to this message:
 Message 12 by Zealot, posted 08-15-2003 6:33 AM crashfrog has replied

  
wj
Inactive Member


Message 11 of 29 (50620)
08-14-2003 11:03 PM
Reply to: Message 9 by Zealot
08-14-2003 8:34 PM


Zealot
You seem to be imbuing "inbreeding" with some sort of mystical, creative powers to generate diversity in a population such as domestic dogs.
Inbreeding (artificial selection) is simply a process which results in the greater likelihood of expression of recessive alleles in offspring. Alleles are different forms of a particular gene which have almost certainly formed from mutation of an ancestral form of the gene.
The population of wolves from which domestic dogs were drawn undoubtedly had variation in it as a result of different alleles for various genes. Inbreeding could be used to fix a particular allele in a breeding population after it first appeared. Often the allele is recessive and inbreeding results in complete removal of the dominant form of the gene from the breeding population.
And there is nothing to stop new mutations arising in a breeding population. These could also be preserved through inbreeding.
The raw material which inbreeding works on are previous mutations of genes in the breeding population and new mutations which arise during the process.

This message is a reply to:
 Message 9 by Zealot, posted 08-14-2003 8:34 PM Zealot has replied

Replies to this message:
 Message 13 by Zealot, posted 08-15-2003 6:43 AM wj has not replied

  
Zealot
Inactive Member


Message 12 of 29 (50635)
08-15-2003 6:33 AM
Reply to: Message 10 by crashfrog
08-14-2003 8:46 PM


Hi, I actually replied to this last night, alas something must have gone wrong.
Do you mean to ask, how often do mutations happen that cause some perceptible change in the phenotype?
Hehe , in simpler terms yes. More specifically how often does a mutation occur that provides a specific advantage to the 'phenotype'.

This message is a reply to:
 Message 10 by crashfrog, posted 08-14-2003 8:46 PM crashfrog has replied

Replies to this message:
 Message 26 by crashfrog, posted 08-15-2003 5:44 PM Zealot has not replied

  
Zealot
Inactive Member


Message 13 of 29 (50636)
08-15-2003 6:43 AM
Reply to: Message 11 by wj
08-14-2003 11:03 PM


Zealot
You seem to be imbuing "inbreeding" with some sort of mystical, creative powers to generate diversity in a population such as domestic dogs.
No, I was trying to find out why there is such diversity amongst dogs, when they are only 30 000 years old as compared to wolves that are well significantly older ? I would still have assumed there would be a great deal of inbreeding in wolves too, but perhaps not as significantly as dogs.
The population of wolves from which domestic dogs were drawn undoubtedly had variation in it as a result of different alleles for various genes. Inbreeding could be used to fix a particular allele in a breeding population after it first appeared. Often the allele is recessive and inbreeding results in complete removal of the dominant form of the gene from the breeding population.
Why such diversity in dogs though ? I remember reading that man apparently almost came to extinction some 60 000 years ago, thus there had to be a substantial amount of inbreeding. Would man just have had less genetic variation in its ancestors ?
And there is nothing to stop new mutations arising in a breeding population. These could also be preserved through inbreeding.
Well this is why I asked how likely it would be that the dog population (as opposed to the wolf) has such diversity. Would it not more likely have been due to significant mutations in the last 30 000 years ?
The raw material which inbreeding works on are previous mutations of genes in the breeding population and new mutations which arise during the process.
So most likely inbreeding would be the most probable cause of species actually getting significant mutations, well enough to cause a significant change to improve its chances of survival ?
[This message has been edited by Zealot, 08-15-2003]
[This message has been edited by Zealot, 08-15-2003]
[This message has been edited by Zealot, 08-15-2003]

This message is a reply to:
 Message 11 by wj, posted 08-14-2003 11:03 PM wj has not replied

Replies to this message:
 Message 14 by Wounded King, posted 08-15-2003 7:05 AM Zealot has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 14 of 29 (50637)
08-15-2003 7:05 AM
Reply to: Message 13 by Zealot
08-15-2003 6:43 AM


Inbreeding isn't a mechanism to generate new variation. Inbreeding can exaggerate already existing variation by producing populations with homozygosity for particular alleles, inbreeding is especially important in maintaining a phenotype for which the allele is reccessive. The point is not that dogs in general have been inbred which has lead to an increase in variation, it is that inbreeding of specific populations has lead to a marked decrease in variation in those populations.
Dogs are particularly diverse because artificial selection can be directed, in the way natural selection is not, and can bring to bear selective pressures much higher than natural selection might normally on very modest changes in phenotype.
Inbreeding isn't the cause of the mutations it simply increases the frequency of the mutation in the population, in the wild this effect would be due to more individuals posessing a beneficial mutation surving and reproducing and a subsequently higher representation of that particular allele in the following generations. Obviously the smaller and more inbred a population the quicker these beneficial alleles are likely to fixate, but also in a small inbred population there are problems with deleterious recessives and genetic drift leading to random fixation of alleles.

This message is a reply to:
 Message 13 by Zealot, posted 08-15-2003 6:43 AM Zealot has replied

Replies to this message:
 Message 15 by Zealot, posted 08-15-2003 10:05 AM Wounded King has replied

  
Zealot
Inactive Member


Message 15 of 29 (50642)
08-15-2003 10:05 AM
Reply to: Message 14 by Wounded King
08-15-2003 7:05 AM


Hi, firstly I know inbreeding doesn't LEAD to mutations, sorry I phrased myself badly. I wanted to know if inbreeding would increase the 'visible' diversication of a species.
Try just to see it from a leyman point of view (PS: that is someone that doesn't know what 'homozygosity' mean )
Inbreeding isn't a mechanism to generate new variation.
I realise that (from the ToE viewpoint), which I stated in my previous response , my question was not whether inbreeding would increase the genetic variation of animals, but the actuall diversification of animals. eg: labrador vs jack russel.
I would like to know the opinion here of why a species (canine) shows such diversity, considering it has only been around for 30 000 years (when compared to wolves)
If your answer is 'artificial breeding' by man, then I would be curious if this is possible using any other animal or species ? Simply put, would we be able to selectively breed elephants to the extent that they have virtually no trunk for example ? For example we could say that a great dane is litterally 7 times the size of a sausage dog, so in theory could we produce the same result with elephants , given the timespan ? IE: Elephants the size of a great dane ?
[This message has been edited by Zealot, 08-15-2003]

This message is a reply to:
 Message 14 by Wounded King, posted 08-15-2003 7:05 AM Wounded King has replied

Replies to this message:
 Message 16 by Wounded King, posted 08-15-2003 10:18 AM Zealot has not replied
 Message 17 by MrHambre, posted 08-15-2003 10:21 AM Zealot has replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024