Buckpasser in the X

[stancaris]

Pan Zareta: Referring to your post on May 26, 2013 at 6 PM you said,

"When you are informed of genome-based evidence that does anything other than contradict your inane notions about the power of the X, please do post it here."

Hmm! Brogers said there are variants on the X that relate to elite performance but only one of them reached statistical significance. What are you going to say I took this statement out of context. There is a variant on the X that reached statistical significance? Is it possible that this variant contributes to the success of a broodmare sire like Buckpasser?

How do the other variants on autosomes contradict the notion that the X chromosome is important? The only thing they prove is that there are variants on the autosomes that relate to elite performance.

You said , " You are cherry picking bits and pieces." Not true, in the discussion of Dink I referred to all the positions in the pedigree (the X passing positions and the nonXpassing positions) and particularly the positions P4 in the third generation, the only X passing position in that generation, and the P6 and P8 positions in the fourth generation, the only X passing positions in that generation and compared those numbers to the numbers achieved by Buckpasser in the Nonpassing positions. Lo and behold, not surprisingly Buckpasser's numbers in those X passing position were for the most part the highest. Adding further evidence that when he is in the X passing position, he does best at getting elite runners.

Quote of Dink's on page 181 of the Racehorse Breeding Theories book:

"That Buckpasser ranks best at P6 and P8 is no surprise at all. He is well known as a great broodmare sire and was the leading broodmare sire 4 times."

Is the above just coincidence that he ranks best at P6 and P8. I don't think so. At P6 and P8 he is transmitting his X chromosome and a portion of it gets to the horses from which Dink derived his numbers. Also when one compares the X passing position numbers at P6 (7.08) and at P8 (11.99) to the numbers obtained at P1, P2, P3, P4, P5, and P7 in the fourth generation which are all NON X passing positions one finds that the P8 number of 11.99 is higher than that achieved by all the NON X passing positions P1 through P5 and P7. And at P6 which comes in at 7.08 we find a number that is higher than all the NonX passing positions P2 thru P5 and P7 with the exception of P1.

[Pan Zareta]

What are you going to say I took this statement out of context.

Not surprisingly, yes, you are still parsing the statement out of context, especially by leaving out the part that says "you are over-rating the variant on the X chromosome". The gist of the remarks in their full context is that the statistically significant X SNP is of, at most, minor importance to elite performance and therefore broodmare sire success. And yes, again not surprisinginly, you are indeed cherry picking bits and pieces of Dink's analysis as long as you ignore the obvious fact that Buckpasser's numbers appear to be anything but dependent upon the % of his genetic contribution, autosomal and/or X. And, finally, you've identified the obligate X passing positions there but not the facultative ones.

[DDT]

Stan

I was going to mention this the other day, it could be that the mtDNA is a primary factor for leading broodmare sires and not the X chromosome. The mtDNA does not go through recombination and is passed on by the dam to all of her foals. I believe that Dink's work actually adds strength to the argument that the influence from the autosomes is much greater than the influence from the X.

DDT

[xfactor fan]

DDT, could you expand on this?

A broodmare sire souldn't have any mtDNA contribution.

[DDT]

xfactor fan

I mean, each daughter of Buckpasser will pass the controlling mtDNA in every foal they produce. It is my understanding that the controlling mtDNA comes from the dam, so the mtDNA could be a primary reason for their elite runners, not his X chromosome.

DDT

[Pan Zareta]

One thing to consider in re. mtDNA - when sire and dam are both elite performers and from the same female family it may increase the likelihood of the foal's receiving nuclear DNA that's 'optimized' for the family's mtDNA haplotype.

[stancaris]

DDT: All these daughters of Buckpasser get their mt DNA from their dam not Buckpasser. That idea is irrelevant to the sex linked traits on the X chromosome and Dink's data which shows big differences in the numbers from nonXpassing positions to that of X passing positions. Mt-DNA cannot be used to explain these differences. The female families of the progeny of Buckpasser's daughters will be very diverse and only come from their dams.

Pan Zareta: Brogers did state that one variant on the X reached statistical significance and that it wasn't in the top ten in importance.

Think about the above statement. The variant on the X reached statistical significance but was not even in the top ten in importance in this regard. Once again a p value of .05 or less means the stat is statistically significant and did not occur by chance. A variant on the X reached statistical significance but it is not important because it is not in the top ten variants that were discovered on autosomes. Accordingly he goes on to say that the variant on the X is not important to the overall success of a racehorse. Well, if its not important to the overall success of a racehorse then how come it reached statistical significance? And how come he stated it was related to elite performance? If a variant reaches statistical significance and is related to elite performance it stands to reason that this particular variant is important to the overall success of a racehorse.

Dink's statement in the fifth paragraph on page 181 of Racehorse Breeding Theories is significant to this discussion and his quote is as follows:

"That Buckpasser ranks best at P6 and P8 is no surprise at all. He is a great broodmare sire and was leading broodmare sire four times."

Dink's analysis of the above positions in the pedigree are vital to the crux of this discussion. The fact that positions P6 and P8 are X passing positions adds support to the idea that Buckpasser's X is an important contributing factor to that success.

[DDT]

Stan

I know they get their mtDNA from their dams and not Buckpasser, it is exactly that point that I was addressing, it is about as irrelevant as super genes on the X chromosome. You are saying Buckpasser's X is a primary reason for his being a leading broodmare sire, I am saying that maybe mtDNA is the primary reason, they are both far fetched, and you are the one saying a primary reason for becoming a leading broodmare sire is X linked because it involves produce from daughters without regard to the influence of the autosomes.

DDT

[stancaris]

DDT: Look at the numbers Buckpasser is given in NON X passing positions in the third generation--- P1 he gets 2.32, P2 he gets 4.75, P3 he gets 3.32.

If the mt DNA of the mares he was bred to was so good then how come his results in P1, and P3 are under the average benchmark figure that Dink identified as 3.74. And Dink said that anything under 3.74 is no good. P1 and P3 are Non X passing positions.

Whereas in the only X passing position in the third generation, P4, Buckpasser gets a 7.05 which is the best number in the third generation and well above the benchmark average.

Dink's results for the X passing positions of Buckpasser clearly shows that the X chromosome is important in broodmare sire success and also in X passing positions. In the third generation his number of 7.05 is higher than that of the values derived in the other NonX passing positions.

In the fourth generation at P6 and P8 (also X passing positions) the numbers stick out like a sore thumb.

The X chromosome is an important contributor to broodmare sire success.

[DDT]

Stan

Buckpasser was a great broodmare sire, make no mistake about that, but as of this writing science has not uncovered evidence to support your position as to the relative importance of genes carried on the X chromosome associated with success as a broodmare sire.

DDT

[Pan Zareta]

Mt-DNA cannot be used to explain these differences.

Buckpasser posts by far his best number in Dink's analysis at 3d broodmare sire where there are three mares between him and the foal but you deny any autosomal or mitochondrial effect on that number, insisting that it was 12.5% +/- of Buckpasser's X that catapulted those graded stakes winners over the finish line first.

Very rational. How astute and insightful of you, Stan.

And thanks for a good laugh.

[stancaris]

DDT: So all the data of Dink stated above does nothing to even cast some light on the importance of the X chromosome for broodmare sire success.

So all the data discovered by Haun and her research associates does nothing to cast some light on the power of the X chromosome. She has taken a certain amount of criticism but she wrote three books on the topic.

So, statements from Alan Porter and Anne Peters about sex linked inheritence carries no weight at all.

So, Rommy Faversham's view that the X chromosome is important to the success of a broodmare carries no weight at all.

Science deals with inductive reasoning and what I did from Dink's data was induce that it was the X chromosome that is important in producing those statistics outlined in the Racehorse Breeding Theories book.

My post of May 27, 2013 at 2:06PM summarizes why I have taken the positiion that the X is important to broodmare sire success. Buckpasser's numbers in all the X passing positions in the third and fourth generation are exceedingly high and these horses from which Dink derived his data (positions P4 in the third generation and P6 and P8 in the fourth generation)
all carry a portion of Buckpasser's X chromosome.

All the runners from which Dink derived his data for the other positions in the pedigree did not receive any of Buckpasser's X chromosome.

[Linda_d]

The X chromosome is an important contributor to broodmare sire success.

That's your opinion, and there's no scientific evidence to back it up. You have decided that Buckpasser has a "magic X chromosome" that made/makes him and his maternal grandsons great broodmare sires. It has barely more credence than Louis' "theory" on the evils of horses having "too much" Phalaris in their pedigrees because, like Louis, you ignore other variables. You are basing your "theory" on empirical evidence that could very well stem from many other causes besides Buckpasser's "magic X chromosome".

Buckpasser and his maternal grandsons who are on the leading broodmare sires list all were elite performers and come from elite female families. That makes it very likely that many of their foals will also come from stakes winning/stakes producing mares from elite female families, so you're dealing with a gene pool that's loaded with the stuff that makes elite performers and/or producers of elite performers, making it much more likely to result in elite performers than, say, breeding a stallion that only won on a claiming level to an unraced mare that comes from a female family that hasn't produced a stakes winner in 5 generations.

Furthermore, how can you make the claim that AP Indy's success as a broodmare sire, for example, is due to Buckpasser's X when AP Indy's first broodmare sire is Secretariat, another great broodmare sire? Why does Buckpasser's X count more than Secretariat's X? And who's to say that the X that AP Indy has isn't mostly genetic material from Gay Missle or Missy Baba?

[DDT]

Stan

I do not deny sex linked traits, I deny super genes on Buckpasser's X chromosome are a primary contributor to his success as a broodmare sire.

I respect most opinions offered by the people you mentioned except Haun, just because you write a few books does not mean that the content of those books are verifiable. It is my opinion that a larger than normal spleen is actually the reason for elite performance or in conjunction with a larger than normal heart.

Have you given any thought as to the data Dink researched to arrive at his numbers such as what type of runners and the total number of runners involved?

Do you believe every thing you read?

DDT

[Pan Zareta]

For a more recent and informed perspective on Haun's work see Matthew Binns' and Tony Morris' Thoroughbred Breeding: Pedigree Theories and the Science of Genetics.