" Hybrid Vigour"

[~Anne~]

But the results hybrid vigour are not something that occur within one generation. Doesn't it take repeated breeding to accurately claim hybrid vigour regardless of the species?

[mita]

While heterosis isn't well understood, it is assumed that the effects come about through increased genetic diversity resulting in fewer homozygote traits. It's a fair bit more complicated than a single disease-causing gene defect introduced into an already inbred population. That's just pot luck, really.

It's not very hard to type "heterosis" into Google Scholar, slap on a publication year filter, and see where the peer-reviewed science is at on this at the moment. It does not at all seem to be limited to crosses between species. Nor is it confined to natural selection.

Personally, if people want to justify their positions re: dog breeding with reference to hybrid vigour, that just makes me think they don't know what they are talking about and leave it at that. I'm not about to give them a lesson in inbreeding coefficients or population genetics. It's a waste of time. Smile, nod and walk away is my advice. There is that much misinformation being spread around from all sides it seems like a little more won't make a shred of difference.

Fair points, corvus.

But I'd add that it's often brought up to justify a dog breeding position... or choice for selecting a crossbreed. From a pretty simplistic line. With the suggestion that 'better' health will follow.

So I'm disagreeing about always remaining silent & walking away. Silence can be taken for assent. I'd at least provide the simple, health-related comments from the US vet.... in only such a context.

http://www.facebook.com/note.php?note_id=443915662016&id=1584362759

[Aidan3]

If they want to claim hybrid vigour, they have to be able to say which traits were improved and by how much (measured objectively).

[mita]

Agree, Aidan, there has to be objective measurement to support any claims.

The 'simple' way the term, hybrid vigor, is used in many of the basic dog contexts, is actually a value judgment. And nothing to do with science.

[Aidan3]

Agree, Aidan, there has to be objective measurement to support any claims.

The 'simple' way the term, hybrid vigor, is used in many of the basic dog contexts, is actually a value judgment. And nothing to do with science.

I'm not even convinced that its a value judgment, more like wishful thinking!

[mita]

Agree, Aidan, there has to be objective measurement to support any claims.

The 'simple' way the term, hybrid vigor, is used in many of the basic dog contexts, is actually a value judgment. And nothing to do with science.

I'm not even convinced that its a value judgment, more like wishful thinking!

I may be charitable! By thinking they might be claiming 'genetic superiority'. :)

It consists of belief statements like... 'It's good to cross breeds.' 'Cross breeding makes healthy dogs.' Like a mix of wishful & magical thinking!

It's amazing, tho', how it's embedded into the world of buying & selling pet dogs. In a simple slogan or two.

[Leema]

Thank-you for all the comments so far. :)

[inez]

Hybrid vigour refers to the mating of different species ... such as lions/tigers; zebras/horses. There are no proper scientific references to "hybrid vigour" occurring when crosses are made within the same species, although there is a lot of non scientific claims on the internet.

From my behavioural genetics textbook "Hybrid Vigour or Heterosis is the increase in viability and performance when different inbred strains are crossed."

When was the book published, and how much credence does the author have?

:)

Cattle breeders use it to get up to 50 kg more weaned weight in the F1 calves, you have to use an entirely different breed againif you want to do a second outcross. But it isnt usually worth keeping the heifers from the second cross as the advandage is downhill from there.

Most breeders who do this either keep seperate their purebred herd and buy in the outcross bull or have two pure herds and only cross a percentage to keep the rootstock for the future.

Do you really want to do that with dogs?

[sandgrubber]

1365553827[/url]' post='6170660']

1365370492[/url]' post='6168609']

1365345590[/url]' post='6168564']

1365306899[/url]' post='6167889']

1365260436[/url]' post='6167509']

Hybrid vigour refers to the mating of different species ... such as lions/tigers; zebras/horses. There are no proper scientific references to "hybrid vigour" occurring when crosses are made within the same species, although there is a lot of non scientific claims on the internet.

From my behavioural genetics textbook "Hybrid Vigour or Heterosis is the increase in viability and performance when different inbred strains are crossed."

When was the book published, and how much credence does the author have?

:)

Cattle breeders use it to get up to 50 kg more weaned weight in the F1 calves, you have to use an entirely different breed againif you want to do a second outcross. But it isnt usually worth keeping the heifers from the second cross as the advandage is downhill from there.

Most breeders who do this either keep seperate their purebred herd and buy in the outcross bull or have two pure herds and only cross a percentage to keep the rootstock for the future.

Do you really want to do that with dogs?

Best answer! Everything I learned in biology says hybrid vigor is real. But that doesn't make it something you want to do with dogs. Vigor doesn't necessarily translate to health, and sacrificing breed characteristics isn't something we want to do.

[alpha bet]

There is also a big question mark over referencing to hybrid vigor in cattle, sheep etc......

These breeding programs are not taking into account the life span of the animal..... most cows are slaughtered at 18 months or so..... sheep even less.... breeding stock are only used for a limited time before they end up at the factory for processing.

We wish our pets to live for 15 years or even more..... and healthy in that time... As stated earlier there is much more than breeding to achieve this, the diet and environment plays a strong role and also the diet and environment of the parents and grandparents etc can also be a factor.

Edited April 10, 2013 by alpha bet

[moosmum]

1365553827[/url]' post='6170660']

1365370492[/url]' post='6168609']

1365345590[/url]' post='6168564']

1365306899[/url]' post='6167889']

1365260436[/url]' post='6167509']

Hybrid vigour refers to the mating of different species ... such as lions/tigers; zebras/horses. There are no proper scientific references to "hybrid vigour" occurring when crosses are made within the same species, although there is a lot of non scientific claims on the internet.

From my behavioural genetics textbook "Hybrid Vigour or Heterosis is the increase in viability and performance when different inbred strains are crossed."

When was the book published, and how much credence does the author have?

:)

Cattle breeders use it to get up to 50 kg more weaned weight in the F1 calves, you have to use an entirely different breed againif you want to do a second outcross. But it isnt usually worth keeping the heifers from the second cross as the advandage is downhill from there.

Most breeders who do this either keep seperate their purebred herd and buy in the outcross bull or have two pure herds and only cross a percentage to keep the rootstock for the future.

Do you really want to do that with dogs?

Best answer! Everything I learned in biology says hybrid vigor is real. But that doesn't make it something you want to do with dogs. Vigor doesn't necessarily translate to health, and sacrificing breed characteristics isn't something we want to do.

Depends on reason. I think placing that restriction on pedigree breeders can be counter productive.Any restrictions in rules shapes attitudes and closes avenues of knowledge and growth.

I grew up in a very different culture,where all dogs were expected to earn their keep,even if just keeping vermin away or as a companion to help gran and keep an eye on the kids.Otherwise it was a just a liability.A pedigree was prized as the specialist. There were times when an all rounder made more sense and the fixed traits of pedigrees were not above being utilised by their breeders.It was not seen as sacrificing anything.

The pedigrees were appreciated most for their reliability in purpose and a second cross was rare.Every one learned from the results...what traits carried most reliably from both parents,planning for purpose,temperament etc....and a serious dog breeder would gravitate to his chosen pedigree with a good understanding of breeding for results through his experiences,knowing just what he wanted from his dogs through using them and living with them every day.

I think it showed a wonderful balance in attitudes and learning was shared for every ones benefit,with the pedigrees showing off their skills every day,working with their neighbours dogs who sometimes filled the gaps.