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Crossover Question

rubberduckyyy September 15, 2011 September 15, 2011

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At the school I went to we had a black paint, named Diamond. Our barn manager told us she was a tobiano. She was bred to a tovero. When the foal was born it was a LWO. She was obviously never bred to the tovero stud again, but our professor said that Diamond (the tobiano) was a "prime example of crossover", because she was a tobiano but was carrying the LWO gene. Is that possible?

Third Peppermint Thu, 09/15/2011 - 11:43

I don't... think... so? Isn't crossover when two genes that are close together and usually inherited together are separated? Like have a black tobiano produce a chestnut tobiano?

Sounds to me like both sire and dam had LWO, but they didn't notice that the mare had it.

rubberduckyyy Thu, 09/15/2011 - 11:51

That's what I thought. She was suggesting, I think, that crossover occured between the "frame overo gene" and the "lethal white gene" and so Diamond was a tobiano who carried the "lethal white gene" without the "frame overo gene". Which I didn't think even made sense... I thought the same as you, that Diamond was a tovero, too, and they didn't know it. I'm nearly positive she was never tested.

Daylene Alford Thu, 09/15/2011 - 12:22

The "Lethal White Gene" and the "Frame Overo Gene" are the same gene. They are not two separate genes that are linked. If the mare produced a Lethal White Foal then the mare carried Frame in addition to Tobiano.

rubberduckyyy Thu, 09/15/2011 - 12:25

Yesssss I knew it. I tried to say that but you know how it is... Professor knows best :roll:. But I guess in her defense she's old so she might not be up-to-date on all the new genetic info.

rabbitsfizz Thu, 09/15/2011 - 13:20

Old is no excuse, I am old and although I will argue a case I am still capable of accepting new ideas- if I can actually understand them, that is!
Close mindedness has nothing to do with age, and you are never too old to learn something new.
Your professor should be thoroughly ashamed of herself, she should have known that such a thing is not possible and that only LWO X LWO will = a LW foal, and should not be expounding ridiculous out of date theory.
What's next, cross miscegenation?

rubberduckyyy Thu, 09/15/2011 - 14:51

Yeah it is kinda sad, considering a lot of people don't quite understand genetics. And it sure doesn't help when your college professor is teaching you the wrong thing!!

Threnody Thu, 09/15/2011 - 21:24

That's a shame. Poor foal. :(

There is another conversation at a different forum talking about the misinformation of roan inheritance in horses being taught in bio classes. The idea that 2 roan horses when bred together produce a white foal. They're using the inheritance of roan in [u]shorthorn cattle[/u] with the example of horses when it doesn't work that way in horses.

Here is a chart that apparently shows that a homozygous recessive roan = dun. I apologize for any brain explosions from the following sentence and image.

[IMG]http://i872.photobucket.com/albums/ab28…]

Don't worry. Roan is still a simple dominant and white patterns don't cause dilutions in homozygous form.

rabbitsfizz Fri, 09/16/2011 - 04:00

Honestly, how can these people even keep their jobs?
I was a teacher- it is your sacred (and I do not use the word lightly) duty- (remember that word, teachers? DUTY) to keep abreast of all new developments and to give the people in your care the most up to date, correct, information that there is. But, I suppose, whilst there are still people teaching children that the world is less than ten thousand years old and that the dinosaurs lived alongside man (yes, over here too) then we should be grateful it is just a few behind the times lecturers we have to deal with not misinformed fanatics!

JNFerrigno Fri, 09/16/2011 - 06:06

I don't know if it's right, I don't think it is. But in both college Biology Classes (intro to Bio, and Biology for Masters) here in Florida they teach you that Roan is...whats the word I'm looking for (sorry really bad cold right now).. Co-dominate? And I know the intro to biology has a picture of a Roan Quarter horse, but I think the masters book is cattle. But in cattle, roan is something entirely different.

Basically in Intro to bio, they teach it with Mendel genetics. RR x WW = RW. Red x White = Red and White Spotted if co dominate. And I don't know if it's right or not, and the more I think about it the more I argue in a circle with myself over it. And you ever try arguing with a sick person? Not fun lol.

TheSwingHorse Fri, 09/16/2011 - 11:35

So sad... so many other people will take away incorrect information and keep it locked away.

As Rabbit said, it is a teacher's duty to keep up to date. To me, just as much as I'd expect my vet to keep up to date with new information. =\

NZ Appaloosas Fri, 09/16/2011 - 19:21

The problem, as I see it, is the APHA's refusal to actually separate out the various "overo" genes/patterns into different terms, and leaving them all lumped into one. Heck, the new poster the APHA has put out "explaining" the different "overo" patterns confused the daylights out of me, and I'm not exactly a newbie in understanding how the patterns work!

Diane

JNFerrigno Fri, 09/16/2011 - 22:00

I only use the term Overo when talking about Frame, and even then I try to always use Frame Overo. Thats how I understand it I guess. I've always thought of an Overo horse, even as a little girl, as a horse typical of Frame pattern. I didn't find out till later about Sabino.

As far as roan in horses goes. When I asked my professor about it. She told me that if it wasn't true they wouldn't have put it in the book, and that the people that write these books had to do the research.

Songcatcher Sat, 09/17/2011 - 08:04

[quote=JNFerrigno]I only use the term Overo when talking about Frame, and even then I try to always use Frame Overo. Thats how I understand it I guess. I've always thought of an Overo horse, even as a little girl, as a horse typical of Frame pattern. ...[/quote]
I really have mixed emotions about that. I answered an ad a year or so ago where someone was wanting a Frame Overo colt. I had one for sale that was lab tested LWO, and answered the ad. He was not a visually marked Frame, and I explained that and sent pictures. I got a snippy reply back that that was NOT a Frame Overo. ~x(

As for the professor, ANY teacher who refuses to acknowledge that a book can be wrong should NOT be a teacher. I deal with certain history textbooks that are riddled with mistakes and I can PROVE them wrong. Usually it is a type error. Sometimes it is a result of the editor being unfamiliar with the geography. Sometimes it is a POLITICAL AGENDA. ~x(

TheSwingHorse Sat, 09/17/2011 - 10:37

Well geez, Songcatcher, if the horse doesn't look like something you bought from Michael's Craft Store, it is NOT a frame overo. Get with the program.

Monsterpony Sat, 09/17/2011 - 11:16

The first page of my high school chemistry book said that the Statue of Liberty was green because it was coated with iron. Just because it is in a textbook, does not mean it is correct.

NZ Appaloosas Sat, 09/17/2011 - 18:26

Admin, can't find a link...saw it at the Stallion Parade (last year?) on a QH/Paint breeder's booth, and went "huh????".

Of course, things aren't helping with the APHA page not loading the search box for me....argle...

Diane

Daylene Alford Tue, 09/20/2011 - 21:01

[quote]I think this article is also the culprit for the "sabino causes blue eyes" crap...[/quote] :rofl

Maybe I should email the APHA a link to this site?

Daylene Alford Tue, 09/20/2011 - 21:24

Most likely not. If they really wanted to learn that would have updated everything already...

rabbitsfizz Wed, 09/21/2011 - 15:43

Apropos of registries receiving only data they want to, one of the reasons that the AMHA is so far behind the times they are walking with dinosaurs, (on colour) appears to be that Barbara Naviaux seems to be some sort of god to them- she, who says confidently that Silver shows on Red.......
I just scrolled on by the post, but it is up on LB at the mo,
http://www.miniaturehorsetalk.com/index…

I guess anyone who can command sums of $400 for a book that marketed at $35 has to be doing something right!