Mitochondrial Dna, Line- And In-breeding

[UltimatePup]

OK, this is quite a little tricky bio-philosophical question!! I've been thinking about this for a while and wonder what other analytical folk think about it...

Sometimes when we are talking about in-breeding I remember that many modern breeds are derived from a very small number of original ancestors - in some cases entire breeds of many thousands of animals are derived from only 4, 3 or even 2 parents. Thus, mathematically, any pedigree breeding is by definition pretty severe in-breeding; there can be no such thing as a true out-cross because those dogs also have the same 4, 3 or 2 ancestors. (Nonetheless, out-crossing is generally considered to be a better breeding practice and seems to work out better in the long run...)

Then, taking it to the next level we find from mitochondrial DNA that 75% of all dogs - Poodles, St Bernards, Wolves, Chihuahas, etc - are derived from a single female ancestor anyway. The other 25% come from only 3 other ancestral females. So, the entire canis crowd is severely inbred no matter which way we cut it. Mathematically even 'cross-breeding' becomes a misnomer because genetically there's no such thing...

Now here's the tripple wammy: Human mitochondrial DNA shows that we are ALL related to a single human female human ancestor too. We, the human race, are as inbred as #$%^@# as well!!!! Everything we have is derived from one set of female DNA. (Hence the story of Genesis perhaps...but that's a whole new discussion.)

Sooooo.....my question is: How does so much apparent genetic diversity emerge from such a small initial gene pool (for both canines and humans)? This is rather like starting out with only eggs, flour and vanilla ... but ending up with chocolate cakes and strawberry muffins as well as vanilla sponges. How does this work?

It seems to me that genomes grow of their own accord over time - that they are not static as usually explained, but build on themsleves such that we end up with additional genes (and consequently the phenomenon of out-crossing turning out better than within-family breeding).

Or, are vastly more genes packaged than are actually expressed in one individual?

Or, maybe it's not really all that much about genes afterall, because we have far fewer of them than we expected to find anyway...?

What does anyone know/conject about this???

Thanks brainiacs

UP

[Pit Man]

OK, this is quite a little tricky bio-philosophical question!! I've been thinking about this for a while and wonder what other analytical folk think about it...

Sometimes when we are talking about in-breeding I remember that many modern breeds are derived from a very small number of original ancestors - in some cases entire breeds of many thousands of animals are derived from only 4, 3 or even 2 parents. Thus, mathematically, any pedigree breeding is by definition pretty severe in-breeding; there can be no such thing as a true out-cross because those dogs also have the same 4, 3 or 2 ancestors. (Nonetheless, out-crossing is generally considered to be a better breeding practice and seems to work out better in the long run...)

Then, taking it to the next level we find from mitochondrial DNA that 75% of all dogs - Poodles, St Bernards, Wolves, Chihuahas, etc - are derived from a single female ancestor anyway. The other 25% come from only 3 other ancestral females. So, the entire canis crowd is severely inbred no matter which way we cut it. Mathematically even 'cross-breeding' becomes a misnomer because genetically there's no such thing...

Now here's the tripple wammy: Human mitochondrial DNA shows that we are ALL related to a single human female human ancestor too. We, the human race, are as inbred as #$%^@# as well!!!! Everything we have is derived from one set of female DNA. (Hence the story of Genesis perhaps...but that's a whole new discussion.)

Sooooo.....my question is: How does so much apparent genetic diversity emerge from such a small initial gene pool (for both canines and humans)? This is rather like starting out with only eggs, flour and vanilla ... but ending up with chocolate cakes and strawberry muffins as well as vanilla sponges. How does this work?

It seems to me that genomes grow of their own accord over time - that they are not static as usually explained, but build on themsleves such that we end up with additional genes (and consequently the phenomenon of out-crossing turning out better than within-family breeding).

Or, are vastly more genes packaged than are actually expressed in one individual?

Or, maybe it's not really all that much about genes afterall, because we have far fewer of them than we expected to find anyway...?

What does anyone know/conject about this???

Thanks brainiacs

UP

Hi Ultima,

You pose a tricky one. My understanding is this, prolonged inbreeding is not a problem provided you rigourously cull the unsuitble dogs. As affordable vet services to the general public is relatively new, nature culled pretty heavily in the past. Most breeds are no older than 200 years and yes now they do have problems, especially if there is a small gene pool. My own breed the Amstaff has regularly opened its studbook in the US to pitbulls to increase the gene pool and try and eradicate genetic problems. I know other breeds do the same thing. Furthermore, working breeds continue to have good health due to rigorous culling. Dogs cannot be identified by breed genetically despite what some scientists claim. What they are actually identifying is closely related individuals as you explained. Dogs in different parts of the world do look different eg boxers, so we breed for different aspects of the genome. As for the genome adding new genes, I have never heard of that before. Environments will select for different genes being expressed, but if the genome were to grow on it's own, it's pretty mindboggling.

Cheers

[BeeB]

Studies have shown that humans and chimps share 96% of the same DNA, just goes to show how a tiny difference like 4% can make MASSIVE diffences between different breeds/species. If all it takes is 4% to produce 2 very very different animals a difference of less than 1% could produce some large differences like the ones we see between 2 different people/breeds of dog.

[Athena GSD]

What a can of worms you could open with this topic.

As BrissyGal says we share most of our genome with chimps (aswell as dogs, mice, cats, etc.)

Our DNA holds literally thousands of genes. Each generation receives half of their mother's and half of their father's genes. Each gene is then paired with another gene. There are dominant and recessive genes, so one gene in each pair is essentially silent (the recessive one) and the dominant one is seen. For example in humans, brown eyes are dominant over blue eyes.

Often disease genes are recessive. Breeding from the same line increases the chance of a pup getting a "bad gene" from both parents and thus getting the disease. For example the royal family in Europe are effectively inbred and haemophilia was historically a major problem in the family.

It gets a lot more complicated though because most diseases are "multifactorial" that is they are caused by a number of genes and also the environment (eg hip dysplasia).

Now as for the question on genetic diversity. Because there are thousands of genes and only a randomly selected half is given by each parent and then only the dominant ones are expressed, in a short time many different forms are seen.

According to Darwinian theory, genes can have random mutations or be expressed in a different way. If this new gene gives an animal some advantage the animal is more successful in surviving, reproducing and thus passing this new gene onto the next generation. This is the simplified basis for the origins of new species and survival of the fittest.

I saw an incredibly interesting show a few months ago that was trying to explain how we got such a diverse range of dog breeds from wolves. A russian scientist used foxes in an experiment. He selected the most tame ones and bred them together (assuming the most tame wolves would have been chosen by the first "dog owners").

To his surprise in a few generations he found a huge variety of coat colours that looked like many of the breeds today (even dalmations!). Their tales began to move up in the air and their ears began to get floppy like some modern dog breeds. These changes were thought to be due to less adrenaline (the fight or flight hormone) in the tame animals compared to their wild counterparts. Adrenaline is responsible for many pathways in the body one of which is pigmentation.

As you can see a minor change in an expression of a gene even without true genetic mutation can have drastic effects on an animal's behaviour and appearance.

I hope that makes sense.

[calliech]

Allelic homologous recombination.

[Pit Man]

What a can of worms you could open with this topic.

As BrissyGal says we share most of our genome with chimps (aswell as dogs, mice, cats, etc.)

Our DNA holds literally thousands of genes. Each generation receives half of their mother's and half of their father's genes. Each gene is then paired with another gene. There are dominant and recessive genes, so one gene in each pair is essentially silent (the recessive one) and the dominant one is seen. For example in humans, brown eyes are dominant over blue eyes.

Often disease genes are recessive. Breeding from the same line increases the chance of a pup getting a "bad gene" from both parents and thus getting the disease. For example the royal family in Europe are effectively inbred and haemophilia was historically a major problem in the family.

It gets a lot more complicated though because most diseases are "multifactorial" that is they are caused by a number of genes and also the environment (eg hip dysplasia).

Now as for the question on genetic diversity. Because there are thousands of genes and only a randomly selected half is given by each parent and then only the dominant ones are expressed, in a short time many different forms are seen.

According to Darwinian theory, genes can have random mutations or be expressed in a different way. If this new gene gives an animal some advantage the animal is more successful in surviving, reproducing and thus passing this new gene onto the next generation. This is the simplified basis for the origins of new species and survival of the fittest.

I saw an incredibly interesting show a few months ago that was trying to explain how we got such a diverse range of dog breeds from wolves. A russian scientist used foxes in an experiment. He selected the most tame ones and bred them together (assuming the most tame wolves would have been chosen by the first "dog owners").

To his surprise in a few generations he found a huge variety of coat colours that looked like many of the breeds today (even dalmations!). Their tales began to move up in the air and their ears began to get floppy like some modern dog breeds. These changes were thought to be due to less adrenaline (the fight or flight hormone) in the tame animals compared to their wild counterparts. Adrenaline is responsible for many pathways in the body one of which is pigmentation.

As you can see a minor change in an expression of a gene even without true genetic mutation can have drastic effects on an animal's behaviour and appearance.

I hope that makes sense.

Wow Athena, I think you killed the thread dead with that one. Damn good explanation on the trot!

[Nekhbet]

mitochondrial and cellular DNA are two separate things. Mitochondria are like the little power factories in the cell. The DNA in there is what is left over from the mother.

When a sperm or egg is created, only half of the DNA in the cell goes in there. So either of the two different chromosomes go into that cell. Then one of those combinations is fertalised. Mitochondrial DNA does not come into any of this process hence can not be changed (discounting spontaneous mutations) so of course for thousands of years be the same. This does not mean we are in bred, as the genetic variation and number of different versions of genes is huge!

If they used a foundation female, then put a male over her all the pups would have the same mitochondrial DNA. The bitches from that litter would then go on to pass on the same mitochondrial DNA to the pups. Since the females are the ones that matter (produce the pups) you will always see that same mitochondrial DNA turn up.

inbreeding and line breeding is decreasing the variation in the cellular DNA. the closer the individuals the more similar their genetics. Keep breeding them together and the offspring's DNA becomes closer and closer to the other dogs. This is undesirable because variation allows recessive conditions to not be expressed (dominant gene masks it) which is the sticking point with DD. Yes the first generation may not SHOW the foundation stock diseases but keep breeding the mutts and it will pop up.

If two different breeds are created over say 2000 years the genetic diversity would be great. Remember we are still breeding dogs so the diversity cant be that huge or it wouldnt be a dog anymore! All dogs have the same chromosomes and genes, but the 'version' of that gene if you like, is what makes the difference. Differences between small, tall, long hair, squished face etc etc

Chimps share 96% of the same genes. The others we dont have in our chromosomes hence we dont look like chimps. All dogs have the same number of genes and chromosomes. If they are missing through a genetic accident usually the pups dont survive past the womb.

[UltimatePup]

Ooh, this is fun!!

...how we got such a diverse range of dog breeds from wolves. A russian scientist used foxes in an experiment. He selected the most tame ones and bred them together (assuming the most tame wolves would have been chosen by the first "dog owners").

To his surprise in a few generations he found a huge variety of coat colours that looked like many of the breeds today (even dalmations!). Their tales began to move up in the air and their ears began to get floppy like some modern dog breeds. These changes were thought to be due to less adrenaline (the fight or flight hormone) in the tame animals compared to their wild counterparts. Adrenaline is responsible for many pathways in the body one of which is pigmentation.

As you can see a minor change in an expression of a gene even without true genetic mutation can have drastic effects on an animal's behaviour and appearance.

Cool! Adrenaline affects/is tied to pigmentation? Interesting... I know that there are pigment chemicals in the brain as well as the skin, but didn't know about Adrenaline... Any more that you can recall on that? I wonder how that would impact humans?

The concept of gene expression versus actual mutation is very interesting. I suspect there may be a wealth of useful information waiting to be discovered in that field of study.

Allelic homologous recombination. :p

OK so you can spell it...but can you say it three times quickly? (I can't - and I did try.) But that sounds like fun. In fact I may try doing some of it this weekend instead of going out drinking. Either way I will feel like a different species by Monday. Seeeeriously...is that one of those 'the sum of the parts is not necessarily equal to the whole' concepts? i.e. Combining the same parts in different patterns produces entirely different structures?

Thanks to everyone who is exercising their neurons with me on this :rolleyes:.

UP

[calliech]

Allelic homologous recombination. :rolleyes:

OK so you can spell it...but can you say it three times quickly? (I can't - and I did try.) But that sounds like fun. In fact I may try doing some of it this weekend instead of going out drinking. Either way I will feel like a different species by Monday. Seeeeriously...is that one of those 'the sum of the parts is not necessarily equal to the whole' concepts? i.e. Combining the same parts in different patterns produces entirely different structures?

UP

Yup. Combining the same genes in different combinations results in diversity. Some traits are polygenic ie they have many genes that contribute to that trait. Recombination of polygenic alleles results in permutions. Here's some fodder:

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?...cb.section.3267

http://www.pubmedcentral.nih.gov/articlere...gi?artid=545587

http://www.pubmedcentral.nih.gov/articlere...cgi?artid=54839

[Jejuna]

I have avery basic knowlege of science and most of what you are all saying is over my head :rolleyes:

However, I was interested in the topic title mainly because my aunt had mytochondrial psytopathy. I'm pretty sure it's spelt this way. For all you science boffins/nurses etc just wondering if either of these issues are related? Maybe the family has been inbred too much :p

[Athena GSD]

Well it is so good to see people putting their thinking caps on (including me). :rolleyes:

[calliech]

I have avery basic knowlege of science and most of what you are all saying is over my head :p

However, I was interested in the topic title mainly because my aunt had mytochondrial psytopathy. I'm pretty sure it's spelt this way. For all you science boffins/nurses etc just wondering if either of these issues are related? Maybe the family has been inbred too much ;)

Mitochondrial psychopathy? Sorry, don't know anything about it. I think it might be more in the forensic criminology realm. There might be a forum on it somewhere. :rolleyes:

[UltimatePup]

I have avery basic knowlege of science and most of what you are all saying is over my head :p

However, I was interested in the topic title mainly because my aunt had mytochondrial psytopathy. I'm pretty sure it's spelt this way. For all you science boffins/nurses etc just wondering if either of these issues are related? Maybe the family has been inbred too much ;)

Mitochondrial psychopathy? Sorry, don't know anything about it. I think it might be more in the forensic criminology realm. There might be a forum on it somewhere. :rolleyes:

Ah, never underestimate the value of correct smelling...er, spelling... You could end up in the wrong hospital with tubes in the wrong bits ;). Jejuna, I think you mean Mitochondrial Cytopathy:

http://www.clevelandclinic.org/health/heal...s/2600/2603.asp?

http://www.bbc.co.uk/health/conditions/mit...ytopathy2.shtml

UP.

[Akitaowner]

I know of a few different physical traits that are said to indicate temperament

eg an akitas tail curl/set the tighter the more difficult to train/stubborn!

i would expect traits that are inherited together are probably found to be in the same region of the genome. This means when the meiosis (fertilisation) takes place and the exchange of genetic information occurs by allelic recombination as mentioned by Calleich :p. As the strands of DNA cross over break and recombine in different places if genes are located together they will more likely be inherited together.

This is often why white colour in some breeds is also associated with deafness....

very interesting topic :rolleyes: (im a molecular biologist and work in genetics!!)

[EddyAnne]

I know of a few different physical traits that are said to indicate temperament

eg an akitas tail curl/set the tighter the more difficult to train/stubborn!

i would expect traits that are inherited together are probably found to be in the same region of the genome. This means when the meiosis (fertilisation) takes place and the exchange of genetic information occurs by allelic recombination as mentioned by Calleich . As the strands of DNA cross over break and recombine in different places if genes are located together they will more likely be inherited together.

This is often why white colour in some breeds is also associated with deafness....

:rolleyes: very interesting topic :rolleyes: (im a molecular biologist and work in genetics!!)

G'day, Eddy here.

A month ago there was a forum topic regarding DNA testing which you might like to read through and maybe add a post or two. As the topic progresses it's revealed that Genetic Technologies and MetaMorphix seem to be in a pre-commercial phase in regards to genetic testing to allow verification of breeds but also to a non-pedigree dog, also know as a bitsa, verifying the mixture of that breed to better assess the suitability of the dog, plus they also mentioned through this research it may soon be possible to offer a genetic test which identifies a dog’s temperament, and also was mentioned "Identifying the "mixture" allows people to assess the temperament of the dog and understand the potential behavioural characteristics," said George Sofronidis, Manager of Animal Diagnostics at GTG. Anyway the start of that topic is via this link address:-

http://forums.dogzonline.com.au/index.php?showtopic=81748

[Jejuna]

I have avery basic knowlege of science and most of what you are all saying is over my head ;) :D

However, I was interested in the topic title mainly because my aunt had mytochondrial psytopathy. I'm pretty sure it's spelt this way. For all you science boffins/nurses etc just wondering if either of these issues are related? Maybe the family has been inbred too much

Mitochondrial psychopathy? Sorry, don't know anything about it. I think it might be more in the forensic criminology realm. There might be a forum on it somewhere. ;)

Ah, never underestimate the value of correct smelling...er, spelling... You could end up in the wrong hospital with tubes in the wrong bits . Jejuna, I think you mean Mitochondrial Cytopathy:

http://www.clevelandclinic.org/health/heal...s/2600/2603.asp?

http://www.bbc.co.uk/health/conditions/mit...ytopathy2.shtml

UP.

Thank You Ultimate Pup. That is exactly what she had. She was first treated as if she had Parkinsons, after a couple of years and her medication not helping, further tests were done and this was discovered. She passed away 2 weeks ago after living in hospital in the elderly section. She was only 58 yrs.

[Pit Man]

I know of a few different physical traits that are said to indicate temperament

eg an akitas tail curl/set the tighter the more difficult to train/stubborn!

i would expect traits that are inherited together are probably found to be in the same region of the genome. This means when the meiosis (fertilisation) takes place and the exchange of genetic information occurs by allelic recombination as mentioned by Calleich :D. As the strands of DNA cross over break and recombine in different places if genes are located together they will more likely be inherited together.

This is often why white colour in some breeds is also associated with deafness....

;) very interesting topic ;) (im a molecular biologist and work in genetics!!)

G'day, Eddy here.

A month ago there was a forum topic regarding DNA testing which you might like to read through and maybe add a post or two. As the topic progresses it's revealed that Genetic Technologies and MetaMorphix seem to be in a pre-commercial phase in regards to genetic testing to allow verification of breeds but also to a non-pedigree dog, also know as a bitsa, verifying the mixture of that breed to better assess the suitability of the dog, plus they also mentioned through this research it may soon be possible to offer a genetic test which identifies a dog’s temperament, and also was mentioned "Identifying the "mixture" allows people to assess the temperament of the dog and understand the potential behavioural characteristics," said George Sofronidis, Manager of Animal Diagnostics at GTG. Anyway the start of that topic is via this link address:-

http://forums.dogzonline.com.au/index.php?showtopic=81748

Hi Eddy,

What they are actually identifying is closely related dogs which happen to be from the same breed. If they test the same breed from different countries then they would get different results unless they came from imports of the original stock. If they they can identify 250 breeds games over, there aren't that many in the ANKC. It wasn't that long ago scientists claimed they'd found the aggressive gene in APBTs. All BS of course.

Edited December 24, 2006 by Pit Man

[EddyAnne]

G'day, Eddy here.

I have an idea of what they are doing, using technology that is SNP based and uses over 130 SNPs to detect the breeds and mixtures of these breeds, and if they are on schedule then currently now they can detect 95 breeds and mixtures of these breeds. That appears to be happening here in Australia with Genetic Technologies, and then this company started working with the US DNA company MetaMorphix in relation to such testings where I thought they maybe also looking for SNP variances within the same breeds, sort of like testing APBTs here and APBTs over there where variances could provide information.

There were previous studies such as by Koskinen MT - 2003 and PARKER et al.- 2004, but DNA wise things have rapidly progressed this even within the past few years where I'm interested in what is happening now as it appears they are beta testing and in the pre-commercialisation stage.

[Erny]

Great reading .......... although I wouldn't have a hope in hadies of intellectually conversing with you guys on this micro-biology level. But I'm finding it interesting and in a language (for the most part ... sometimes I don't understand the 'initials' used for certain things) I can follow. Thanks. ;)

Edited December 24, 2006 by Erny