Genetics question about hybrids

[Sally PB]

Genetics question... Pardon my ignorance.

I keep reading that the F1 hybrid cross is likely to have more vigor, disease resistance, etc. than the original two pure breeds, in my case, BO over BA. But those traits don't carry over to the F2 generation. Or is it that they *may* not carry over? Can someone explain why this is, in the dumbed down version of genetics that I might understand?

Here's what my brain thinks might be the reason. My F1 equals BO x BA. Say F1 is like mixing blue and red to get purple. F2 takes the blue, red, and purple, tosses it in a pot, stirs it up, and .... ? If blue and red and purple all work well together, voila! It's all good. (Purple is my favorite color.)

But say it's more like mixing yellow and black. F1 might be as pretty and useful as honeybees. F2 might just look and act like mud.

Is this anywhere close to what is going on?

I originally had this on another thread, and someone suggested I post it here. Thanks for any insight.

 

[ChickenCanoe]

In a nutshell, the primary reason for more vigor is multiple genes in the mix.
With less genetic diversity, the more likely genes will be compounded from any one mating. The more closely related a grouping is, the more problems and less vigor they will have.
Inbreeding depression - Wikipedia
Unraveling the genetic basis of hybrid vigor | PNAS

 

[Sally PB]

Thank you.

 

[The Kooky Kiwi]

Many moons ago a breeder of dogs offered this explanation to my parents:

A pup receives a combination of genetic traits from it's parents. When you breed two "related" parents there is an increased chance they will share similar genes which then become combined or magnified in the pup. The risk with this type of breeding is that it has the potential to not only result in really good pups - but also result in really bad pups - and ethics requires a breeder to minimise the chance of those poor outcomes.

Sometimes it is necessary or desirable to "line breed" - when we want to selectively breed for a given trait and we can use mathematical certainty that it will pass via certain birds by virtue of a known parentage. However the practice is best "moderated" by including unrelated birds to the breeding program as often as possible - to reintroduce the genetic diversity and minimise the perpetuation of non desired traits.

 

[edgarmongold]

There’s a major difference between poultry and mammals/people when using the term genetic diversity.
Seems like individuals use what happens in mammals should apply to poultry.
There are cases where inbreeding poultry leads to problems but usually more due to selection of breeding stock than inbreeding.
One only has to look at fighting game strains that have been bred without outside blood being added for 3 generations from grandparents to parents to grandchildren.
One has only to review the small number of ancestors used in the winners of the early egg laying contests.
My line of New Hampshire Bantam can be traced back to a single male #255.
I used his original mate, kept his granddaughters great granddaughters and great great granddaughters.
Anytime I made a mistake in a mating I could jump back as far as needed.
This allowed me to be able to set traits and bring to surface any undesirable recessive traits.
Father daughter granddaughters etc
Uncles to Nieces Brother Sister Half brother to half sister all have been utilized.
Cull hard and forget about running 2 males over 20 females.
Does not work.
If you want that quick burst or shot of vigor send a dozen pair mated chicks to someone in another state and get select offspring back and use them in your breeding program.
Work with a couple of friends that maintain the same bloodline.
Cull cull heavy for strong robust breeding stock that maintain both meat and egg production.
Genetic diversity hybrid vigor sounds good on paper but you bring both the good and bad traits when you make the cross.
Big breeding operations produce their hybrids by crossing two tightly bred strains together in mating that they know what will be produced.
This is why breeding their hybrids together will not reproduce their results.
Line breeding in breeding isn’t for everyone.
It gets a bad rap from individuals passing along information from the internet or relayed to them second or third hand.
Something to think about.