Genetic Purity vs. Hybrid Vigor

[NeilV]

The discussion about Russian bees and their breeding got me to wondering.

On the one hand, I understand the idea that hybrid vigor results from mixing diverse genes when breeding. I have read that people worry that the gene pool for bees has narrowed too much, since all the bees breed by breeders from breeder queens are limited to a couple hundred sources and varroa etc. has hammered so many bee populations.

Then, I read in Bee Culture a couple months back that people who are using Russian bees stress the importance of have pure bred Russians not Russian crossed with any old drone. The breeders in the Russian Bee Breeders Assoc. stress that they are striving to only produce pure Russian bees. That also assumes that genetic purity is the goal.

Why is it important in the case of Russian bees that they be pure bred? What happens when they are not? Why does hybrid vigor not work in that context? Are the people running the Russian breeding program already doing all the right crosses between bees to get the diversity they want/need?

Not trying to start an argument, just wondering.

Ndvan

[Beaches' Bee-Haven Apiary]

I'm no expert... so I'll let MB tackle most of those!

I think the main reason Russian purity is stressed is so that the naturally resistant genetics are not diluted. I think the best breed would be one prduced in the area these bees are taken from, thus providing natural genetic variety, but with similar resistant traits. When they're brought into a foriegn opperation the genetics should be kept diverse among the Russian stain. In other words... If you take 5 Russian colionies, stick them in a mating area with no other bees and produce queens, you will get pure Russian stock. But if you keep using those colonies and thier offspring without importing more native Russian stock, you will run down and harm the genetic pool of your bees... they start diluting their own genes. Genetic variety is important in any animal, with the Russian stain of bees it is still vital. These bees have naturally, over time, developed a resistance to vorroa destructor but in the wild these bees are still genetcly diverse, yet they share very similar characteristics. In order to capture this resistance scientist must maintain genetic "purity" withing the Russian strain, however, they also must mainain a threshold of genetic variety to maintain strong, healthy, productive bees.

-Nathanael

[Michael Bush]

>On the one hand, I understand the idea that hybrid vigor results from mixing diverse genes when breeding. I have read that people worry that the gene pool for bees has narrowed too much, since all the bees breed by breeders from breeder queens are limited to a couple hundred sources and varroa etc. has hammered so many bee populations.

Diversity is good for a species' gene pool.

>Then, I read in Bee Culture a couple months back that people who are using Russian bees stress the importance of have pure bred Russians not Russian crossed with any old drone. The breeders in the Russian Bee Breeders Assoc. stress that they are striving to only produce pure Russian bees. That also assumes that genetic purity is the goal.

Predictability is the goal of any breeding program and that is always the opposite of diversity. If you breed any animal for specific characteristics, what you are really doing is breeding out the diversity that would give you different characteristics.

>Why is it important in the case of Russian bees that they be pure bred? What happens when they are not?

Then the characteristics you bred for get mixed with genes that don't have those characteristics. If it's a recessive trait you lose those the first generation where a dominant gene blocks that characteristic. In the second you might even lose a dominant characteristic when it gets lost altogether in that particular line.

>Why does hybrid vigor not work in that context?

Hybrid vigor is an entirely different issue. It only happens when lines that have been separate come together. It works best if those lines are carefully chosen to enhance the characteristics you want and not the ones you don't want. For instance an F1 hybrid in bees is often very agressive. It takes a careful cross to get one that isn't.

> Are the people running the Russian breeding program already doing all the right crosses between bees to get the diversity they want/need?

No breeding program (except maybe Dann Pruvis') is built around diversity. They are built around selective (read "less diverse") breeding. All selective breeding does is remove the characteristics you don't want so that you consistently get what you want.

For instance, if I can get a heterozygous (all sets of color genes are for black) black horse and breed it to a heterozygous black horse I will get a heterozygous black offspring. There is no possibility of diversity in the realm of color if I do this. If I breed cows to have large udders and give much milk, I am not breeding something in, I am breeding something out. I'm breeding out the possibility that I will get a cow with a small udder that gives a small amount of milk. When you do selective breeding you breed out the genes for the characteristics you DON'T want so that you consistently get the characteristics that you do want. After all that work, you don't want to allow those genes you bred out back into the gene pool.

In other words, diversity is bad for a breeding program.

Now the evolutionists will try to argue this, and you can expect me to not respond, but no real breeder nor any geneticist will. This is and always has been the goal of selective breeding.

[BjornBee]

I think there may be some confusion of what diversity is.

There is diversity within the lines, such as MB pointed out in regards to such items as color, etc. A breeder is selecting for a consistent criteria to benefit from, in choosing such items as gentleness, color or anything else. You don't want a vast variance (diversity) of output that is from wide spectrum. You want all good honey producers, you want all hives to be gentle, you want all hives to handle mites, etc.

Then there is diversity from a breeding aspect. This is why the Russian program has each breeder responsible for 2 lines of Russians. Each breeder is selecting for the same traits, but with separate lines. And its these lines that then can be selected from, for breeder lines, drone lines, etc. You can not maintain a line of bees without having a long term plan of using hybrid vigor and crossing of the different lines. That's why the Russian breeder association is setup the way it is, and when you order breeders from such places as Glenn's, that getting the different "colored" lines is important from one year to the next.

So there is diversity within the traits that individual lines carry, those are what one selects for to maximize the traits that are desirable. Then there is diversity between the individual lines that produce hybrid vigor, ward off inbreeding, and can be used for other goals.

I think the term "diversity" is used loosely, but it has different applications that should be defined.

It should be noted that its not one or the other. (Purity or hybrid vigor) You can achieve both by a program such as the Russian association. And you can have hybrid vigor without a closed system of using exclusively pure similar lines (all russian), such as what Brother Adam did when he produced the buckfast by taking many lines(italian, carni, etc.) and selecting for the best traits within the lines.

And it should also be noted that the whole use of the term "purity" or "pure", is certain to be incorrect.

[NeilV]

Thanks, I think you straightened me out. Just to be sure I follow, this is, taken together, my understanding of what everybody had to say:

1. The goal of a breeding program is to eliminate diversity as to specific genes/traits to eliminate undesirable genes/traits.

2. Eliminating diversity in general is bad.

3. Breeders of anything face an inherent conflict between 1 and 2.

4. A really good breeding program tries to manage that conflict by having multiple lines of breeding stock where breeding is done to select for traits (eliminate diversity) but maintain other diversity to the extent possible. In other words, everybody ends up with blonde hair, but nobody marries his cousin.

5. The Russian program has tried to do just that, which is why they cringe at the idea that somebody would open mate their bees and ruin all the work they did to attaining the goal in paragraph 1.

Does that about sum it up?

Also, Michael, I don't want to start an argument over the meaning of life, but what did you mean by the "evolutionists will argue" comment. (Just so you'll know, my personal view is that God is the creator -- after all, why does anything exist at all -- but am interested in the idea of just how he did it. I also have a best friend who both has a biology degree and is a hard-core Creationist, and we have had many talks about that subject).

Also, Bjorn, what did you mean by the use of the term "pure" is certain to be incorrect?

[Kieck]

For instance, if I can get a heterozygous (all sets of color genes are for black) black horse and breed it to a heterozygous black horse I will get a heterozygous black offspring. -Michael Bush

I believe you mean "homozygous" in all instances where "heterozygous" was used above.

So there is diversity within the traits that individual lines carry, those are what one selects for to maximize the traits that are desirable. Then there is diversity between the individual lines that produce hybrid vigor, ward off inbreeding, and can be used for other goals. -BjornBee

I believe the goal is to maintain enough diversity to avoid inbreeding depression, yet reduce diversity enough to increase predictability within the breeding program (like Michael Bush suggests).

"Hybrid vigor" refers to a cross between two different breeds or races, not to a cross between two different lines within a breed. Think of cattle breeding. The "hybrid vigor" seen in black baldies, for example, comes from crossing a black angus and a hereford. The offspring from two separate lines within the black angus breed will not have the "hybrid vigor." The reason, in a simplified explanation, is that even separate lines within a breed are still remarkably similar to one another.

In other words, diversity is bad for a breeding program.

Now the evolutionists will try to argue this, and you can expect me to not respond, but no real breeder nor any geneticist will. This is and always has been the goal of selective breeding. -Michael Bush

If your comment about arguing the point refers to your statement that, "Diversity is bad for a breeding program," I won't argue it. (And I am an "evolutionist.") Even in nature, selective pressures restrict genetic diversity. This about the pressure put on honey bees by Varroa mites: only the bees with one or two specific traits, perhaps, are likely to survive on their own once Varroa became a problem. All of the other traits in all susceptible bees would be lost. That reduces (not increases) genetic diversity.

[BjornBee]

edited due to some unexplained reason.

[BEES4U]

If you want to improve the gene pool.
1. Buy semen straws
2. Buy a purebred sire
3. Breed up to the standards of perfection without inbreeding
The Cocker Spanial was a good dog in the 50's. To much backyard breeding ruined the pedigree. (The term is close breeding) Check out the genetic negatives of in-breeding in animals and see what happens.
Set your genetic goals 10-20 years into the future.
Breed record. Breed record
Can you afford to buy purebred Bull?
No, buy his semen straws by selecting the bull index that fits your operation.
The genetics work is out there. It is tested and proven.
A large beekeeper located in the Mid-west did a trial for his own research and proved that his new strain of queens was superior to his old stock.
The new strain pulled through winter quite well. The control block had very high winter dead outs.
What was the new strain of bee?
They were Russians!
Imported by the USA.
Selected by the USA.
Tested in the USA.
Proven in the USA.
Accepted in the USA.
The Russian traits are carried into the 3-4 generation from a instumentaly inseminated queen's daughters.
FYI
I have over wintered my Russian breeder queens in 1/2 length top bars with full depth side bars. Last year was the worst drought in 130 years. The bees covered 8 frames going into winter with no pollen patties or substitutes being fed in the fall. No syrup. I basically stressed the bees on purpose just to see how they would perform. They now cover 4-6 frames 2/06/08.
The other reason that I over wintered them in small nucs was because I did not want the queen to get burned out in a larger hive,
My othe breeder queens performed as well.

Best regards,
Ernie
Lucas Apiaries
(I start grafting in late February)

[JC]

The discussion about Russian bees and their breeding got me to wondering.

On the one hand, I understand the idea that hybrid vigor results from mixing diverse genes when breeding. I have read that people worry that the gene pool for bees has narrowed too much, since all the bees breed by breeders from breeder queens are limited to a couple hundred sources and varroa etc. has hammered so many bee populations.

Then, I read in Bee Culture a couple months back that people who are using Russian bees stress the importance of have pure bred Russians not Russian crossed with any old drone. The breeders in the Russian Bee Breeders Assoc. stress that they are striving to only produce pure Russian bees. That also assumes that genetic purity is the goal.

Why is it important in the case of Russian bees that they be pure bred? What happens when they are not? Why does hybrid vigor not work in that context? Are the people running the Russian breeding program already doing all the right crosses between bees to get the diversity they want/need?

Not trying to start an argument, just wondering.

Ndvan

I do not want Russian hybrid queens! By a hybrid I mean a Russian queen bred with Italian drones, etc. A Russian hybrid would not be as good at resisting mites. Since I do not use any treatments for mites, I want 100% Russian bees.

There is gene diversity within the Russian bees, however. The USDA Bee Breeding Lab in Baton Rouge maintains different lines of Russian bees. The production queens that I get have a different genetic diversity each year.

[Michael Bush]

>Does that about sum it up?

Yes.

>Also, Michael, I don't want to start an argument over the meaning of life, but what did you mean by the "evolutionists will argue" comment.

Some on this board will argue that evolution has something to do with breeding. I don't wish to spend my time on this discussion as evolution is irrelevant to breeding.

>I believe you mean "homozygous" in all instances where "heterozygous" was used above.

You are correct. Sorry, at 6:00 am I had a brain fart.

>"Hybrid vigor" refers to a cross between two different breeds or races, not to a cross between two different lines within a breed.

Not necessarily. You can get the same vigor from two lines of the same race. That's what the Starline was and what many hybrids are.

[Bizzybee]

"I have some that have some Russian influence as far as survivorship goes, however, they do not display the degree of aggression that pure Russians are know for."

Pure Russians aren't known for aggression. I think that has come from sellers claiming purity when in fact they were crossed causing the aggression.

I'm not sure where this is going?? There is only one source of Russian bees to my knowledge. And that's from the USDA. They are not going to get any more "pure" than that. And only if II is used from that point of release. Unless you follow the program that they are using to maintain the lines, then you can only start inbreeding. Increasing diversity isn't an option, decreasing it is if you are looking to mask a trait.

Aside from II purity has no course other than diminishing return. Is that a bad thing? Not in my opinion, but it does not support any theory of purity.

Grading for purity and grading for traits have nothing in common in my estimation. If pure is what you want for whatever reason then so be it. If specific traits or a wide range of traits are your preference then choose accordingly. But simply crossing bees randomly is going to yield random results at best. As Micheal mentioned with repeatability, that isn't easily obtained and unless II isn't incorporated somewhere along the line it isn't sustainable. And then you wind up full circle in the maintenance of a line in the same way that purity of the Russian bees is maintained.

But then what happens when the next threat comes along and the line isn't capable of coping with the threat? You make changes or introduce traits from another line. But, which is possible when purity isn't an issue.

[MichaelW]

Aspera, try this url for Laura L. Bryant's Thesis
Examining Varroa-resistant honey bee queens from commercial breeders colony productivity, hygienic behavior, suppression of mite reproduction, and the relationship of juvenile hormone III to mite abundance / .

http://etd.utk.edu/2004/BryantLaura.pdf

I'm not sure if its published in a journal.

I don't wish to spend my time on this discussion as evolution is irrelevant to breeding.

But your the only one spending time on this discussion. :confused:

[BjornBee]

Oh great MichaelW, I just posted a thread on the subject..

[aszalan]

Aspera, try this url for Laura L. Bryant's Thesis
Examining Varroa-resistant honey bee queens from commercial breeders colony productivity, hygienic behavior, suppression of mite reproduction, and the relationship of juvenile hormone III to mite abundance / .

http://etd.utk.edu/2004/BryantLaura.pdf

I'm not sure if its published in a journal.

nothing on the ISI science citation index for a journal article by Bryant on this. one great thing about the internet is being able to find MS and PhD thesis and dissertations that has never been published.