Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: chris on 22/04/2017 10:12:40
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Alan in Mexico wants to know:
Is it true puppies get the best out of both parent's genes?
What does everyone think?
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Hi Alan,
short answer: No... although it of course depends already on what someone would judge as "the best" in a parent. For example a breeder might rank some traits as favourable (e.g. coloration, a certain figure, short nose, hairstructure and so on) than someone with a medical backround would rank as bad (for example a short nose could make it more difficult for the animal to breath and should therefore not be desirable).
But even if we just consider the opinion of one person, it is not always the traits this person desires the most that will be passed on more likely.
For the longer answer, the basis for understanding what is going in the inheritance of traits are the Mendelian Laws of inheritance.
They basically say
a) In the genes each trait is coded for with two alleles, that migh look like this: Aa. When the trait gets passed on, the two alleles will separate into A and a and will recombine with the two alleles of this trait in the partner. So you will always have one allele of the mother and one of the father in the offspring to code for a trait. In this visualization the big letter is coding for a dominant allele, meaning that in a combination with a recessive allele the dominant one will be the one that gets expressed. The small letter is a recessive allele, meaning it is the one that gets supressed in a combination.
b) If the parents have a pure genetic backround for a certain trait (homogenous), for example the mother is a white dog (ww) and the father is a black dog (BB), then the emerging offspring will all be heterogenous (means, a trait is now not "purely" coded for anymore) and will all be the same. In this example alleles expressing "white" are recessive (small w) and alleles expressing black are dominant (big B). Therefore in this case all the emerging puppies would be black as all the new recombined alleles would look like this: Bw (B from the father and w from the mother). This kind of heredity is therefore called dominant-recessive. There is another possibility where the alleles from the mother have the same rank as the alleles from the father, so the offspring would for example look like this: BW .. in this case neither black nor white is dominant, so the offspring would possibly be grey. This is called intermediate heredity. So if the person ranking the traits would like to have white dogs, it would not be very happy with both scenarios.
3) However, you can get white dogs from this offspring again with a certain probability. If you now mate two individuals with heterogenous backround (Bw) you will now get offspring that might differ from each other quite a lot. All possible recombinations would now be those: BB (black dog, homogenous), Bw (black dog, heterogenous), ww (white dog, homogenous). Due to probability, the chance to get a white dog is only 1/4, as is for getting a homogenous balck dog. About half of the offspring will still be heterogenous and thus, while you would be sure that mating white dogs with each other would always produce white dogs, it is still difficult to say what offspring you would get in the next round if you use the black ones.
This is a simplified model, where one trait is coded for by just one allele. In reality traits are often coded for by several alleles and some alleles are responsible for several traits, making the whole thing a bit more complex.
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As Atrox pointed out, it all depends on what breeders consider the best traits. Often this is based on superficial things, which characterize a breed, often leading to puppies who may have future medical problems. In the USA, the German Shepherd is bred to have a low rider hind end. This may look cool to the GS enthusiast, but it often leads to hip problems later in life. If you bred to remove the hip problems, this may change the style of the dog. They may get smaller and become more square.
The healthiest dogs, which are not always the prettiest, are often the mutts. The mutts form when you allow the dogs to decide which are the best features of the parents. Dogs tend to pick things such as good health, and will often sacrifice shallow looks. The mutts tend to converge dogs breeds back to a center.
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Can agree to the pavement special being the best, generally the sortaterrier is a good indoor dog, and the sortador is a good yard dog. They are sort of like a terrior and a labrador in each case, just they are close to a generalised nondescript brown mostly dog. Best you can get.
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If the "best" genes from the dog and bitch went forward to the pups then, no matter how you define "best", the pups in a litter would all look the same because they would all have the same "best" genes.
The don't.
So the answer is no.
Also this process would need for the sperm and egg to somehow look into the future to see what combination of genes would be "best"
How would that be plausible?
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If you compare a highly-bred pug or bulldog, with bow legs, useless tail, bulging infection-prone eyes, slobbering chops and permanent breathing problems, with a wolf/husky/bitsa, the answer is obviously "not always". The healthiest family dogs I meet in the park are known locally as "Wood Green Wonders" - a haphazard mixture of working and racing breeds from the local rescue centre.
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About 10% of Huskies get cataracts.
http://www.yourpurebredpuppy.com/health/siberianhuskies.html
All the "recognised breeds" of dogs have been inbred for so long now that they essentially all have problems of one sort or another.
The premise of the OP seems to be the sort of propaganda spread by the breeders.
The best thing that the "German Shepherd breeders association" could do for their dogs is to disband and they would do so if their real intention was the best interests of the dogs . However it seems their true intent is preserving the vanity of the owners.
The same goes for the other breeds; I just chose GS because someone else already mentioned them, though they did get some remarkably bad publicity at a major dog show a couple of years ago.
http://www.telegraph.co.uk/news/uknews/12193472/Crufts-plunged-into-cruelty-row-over-deformed-German-Shepherd.html
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Yes, thats actually really bad, a lot of breeds have diseases and problems typical for that specific race.
The GS is one of the many bad examples.
We have a GS as a family dog, but actually an old breed that tends to have longer hair. As they are not acknowledged by the FCI as a breed and also the GS breeding association only since recently (2010) allow them to officially breed, this race has not (yet) been destroyed so much by breeding and they are in general much more healthy then GS and especially they did not follow this trend in the falling backline. A picture from our dog shows this quite good I think:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Ffoto.arcor-online.net%2Fpalb%2Falben%2F33%2F5987833%2F400_3436333336646232.jpg&hash=41794e8d8d55f8b7f03992978cd3953c)
However, I myself will surely prefer to go for a mix-breed (from a shelter) when I will have the time to have my own dog at some point, as I generally have mixed feelings about this professional dog breeding. I do not like that system very much. I sometimes have the feeling that responsible breeders are a minority in this whole business and for many breeders to breed a healthy dog is not the highest priority (which it should be).
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We bought a "sausage dog" from a breeder.
We bought the runt of the litter, as we weren't interested in showing it, and it was cheaper. This one obviously didn't get the best genes from its parents,
I expect it will suffer back problems as it gets older, as this problem is common in this breed.
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We bought a "sausage dog" from a breeder.
We bought the runt of the litter, as we weren't interested in showing it, and it was cheaper. This one obviously didn't get the best genes from its parents,
I expect it will suffer back problems as it gets older, as this problem is common in this breed.
It's a known problem- and you paid the breeder for making it worse.
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Evidently, no ... https://www.theguardian.com/lifeandstyle/gallery/2016/jun/25/worlds-ugliest-dog-competition-2016-in-pictures
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Breeders of "designer breed" dogs tend to advertise their puppies as all having the most desirable traits of each breed. A common example is when the breeder of Labrador X poodle (commonly referred to as the "labradoodle") will claim that the dog is highly intelligent (implying a poodle trait), non-shedding (poodle trait), easy to train (Labrador trait), friendly (presumably a Labrador trait), and hypoallergenic (made-up trait).
Strangely enough, they never seem to entertain the idea that the puppies could be a boisterous (Labrador), allergic to everything (poodle), hypochondriac (poodle), indiscriminate eater of garbage (Labrador) with horribly hairy ears (poodles) and chronic ear infections (both breeds). Genetic wishful thinking...
The actual puppies could be some random combination of the genes of each parent, and may even be different from the other litter mates. Just like puppies in the same litter can be different-coloured and different-sexed, they can also be of different disease status. If it's lucky, the pup might not get a certain defect that its parents had. If it's unlucky, it may end up with two deleterious genes and be clinically diseased compared to its parents (if each parent only carries one deleterious gene for a particular trait).
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Breeders of "designer breed" dogs tend to advertise their puppies as all having the most desirable traits of each breed. A common example is when the breeder of Labrador X poodle (commonly referred to as the "labradoodle") will claim that the dog is highly intelligent (implying a poodle trait), non-shedding (poodle trait), easy to train (Labrador trait), friendly (presumably a Labrador trait), and hypoallergenic (made-up trait).
Strangely enough, they never seem to entertain the idea that the puppies could be a boisterous (Labrador), allergic to everything (poodle), hypochondriac (poodle), indiscriminate eater of garbage (Labrador) with horribly hairy ears (poodles) and chronic ear infections (both breeds). Genetic wishful thinking...
The actual puppies could be some random combination of the genes of each parent, and may even be different from the other litter mates. Just like puppies in the same litter can be different-coloured and different-sexed, they can also be of different disease status. If it's lucky, the pup might not get a certain defect that its parents had. If it's unlucky, it may end up with two deleterious genes and be clinically diseased compared to its parents (if each parent only carries one deleterious gene for a particular trait).
Loved the "made up trait" line. Made me laugh out loud.
This sort of selective advertising is not unique to pets; "High in calcium" often features on packets of cheese, but "high in saturated fat" is often left off for some reason...
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This sort of selective advertising is not unique to pets; "High in calcium" often features on packets of cheese, but "high in saturated fat" is often left off for some reason...
Haha. That is true! High sugar, high fat foods are a "great source of energy". High fat foods are "low GI". And there is "gluten-free ham"...
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The "hypoallergenic" trait isn't entirely made up. There's quite an interesting story behind the original labradoodle cross. The man in charge of breeding guide dogs (seeing eye dogs) tried to create a suitable guide dog for a blind woman who happened to have a husband who was allergic to dogs. After some attempts at breeding a labrador with a poodle, he was able to get a pup that both a) showed a suitable temperament and obedience to succeed as a fully-trained guide dog, and b) was less of an allergic trigger to the husband compared to other dogs. The other pups in each litter had variable qualities for each of those two requirements, but still needed to go to homes. At the time, nobody wanted to give a home to a cross-bred dog, so they marketed them as a fancy "new breed", the labradoodle, to make them seem more desirable. Since then, every backyard breeder with one of each dog has been able to flaunt labradoodle pups for $$$$s, claiming all the best traits from each parent including being "hypoallergenic". Whether or not these dogs shed or trigger allergies...who knows. It's not like any of them are tested in shedding or allergy trials.
http://www.telegraph.co.uk/lifestyle/pets/10626590/Breeders-regret-over-creating-labradoodle.html