Raise A Native Sire Line 3 year olds

[stancaris]

DDT: Yes, we are discussing the Y chromosome and its function. The Y chromosome carries genes that make males run faster than females in general. The Y chromosome certainly carries genes that make males superior performers. There are performance genes on the Y chromosome. I do not think you can doubt that.

If all Y chromosomes are the same in all horses then how do you account for the superiority of the Raise A Native sire line in the Kentucky Derby since 1969 where it has generated 17 male winners? In the Preakness where it has gotten around 16 winners and the Belmont where it has gotten 18 winners. No other sire line even comes close to the above stats.

Northern Dancer went to stud at around the same time as Raise A Native and became just as dominant or even more dominant in general and yet the Northern Dancer sire line has meager stats in the Triple Crown. Something like 4 or 5 Derby winners , Preakness winners 4 or 5 and Belmont winners around 5.

Obviously, the Y chromosome in horses carries performance traits. The key question here is why has the RAN sire line become so dominant in the Triple Crown races if all Y chromosomes are exactly the same?

[Pan Zareta]

The Y chromosome contributes to performance.

Only by virtue of the fact that males in general have an athletic performance advantage and the y is what makes them male. There are only three extant sire lines in the TB, the Godolphin via Matchem, the Byerley via Herod, and the Darley via Eclipse. The vast majority of Derby winners trace in 'tail male' to the latter. Eclipse was foaled 248 years ago. The average mutation rate of yDNA is measured in thousands, not hundreds, of years. Mr. P., RAN, Northern Dancer, *Nasrullah, Nearco, Phalaris, Hyperion, *Teddy, *Leamington. et al., are all the same "sire line".

[DDT]

Stan

Because we are talking about performance in the Derby, Preakness and Belmont you must consider the maturity or lack thereof, the trip, track condition, training methods and many other aspects including a limit on starters in the races. The Y does not contribute genes that make males bigger, stronger and faster, it determines the sex of the foal. As I stated earlier, this is accomplished by the remaining 63 chromosomes and genes present in a male foal.

DDT

[stancaris]

DDT: The data supports the conclusion that the Y chromosome makes males faster than females. The only macroscopic difference between males and females is the presence of the Y chromosome in males and the absence of the Y in females.

Generally males are faster than fillies. How many fillies have competed in the Derby, Preakness and Belmont stakes thru history? On the average they just cannot run as fast as colts. There is no disputing that.

The Y chromosome carries performance genes. Thats a fact that is supported by the history of race times comparing the two groups (male vs female).

The question that boggles my mind is as follows: Why has the RAN sire line been so dominant in the Triple Crown races since 1969 if all Y chromosomes are exactly the same?

One possible explanation has to do with the interaction of genes on the Y chromosome with other genes on autosomes. Perhaps autosomal genes carried by the RAN sire line can only work their effects when combined with products produced by genes on the Y? It is a known fact that genes on one chromosome can influence how genes on other chromosomes produce their effects.

[aethervox]

I would like to point out one unique characteristic of the equine Y chromosome.

There's a repeated sequence in the DNA; one occurs in the Pseudoautosomal Region - PAR - (the region that does recombine with the X gene) and the other occurs in the male specific region - MSY. - see the paper at http://www.ncbi.nlm.nih.gov/pubmed/18544933

As far as I know, they haven't figured out what this particular sequence encodes, but it could explain why different 'sire lines' perform better than others (i.e. if there's a mutation in the PAR section and not in the MSY section, then whatever the MSY section makes isn't the same as what the PAR section makes).

Also, genes in the PAR region escape X-inactivation, so the repeated gene sequence occurs 3 times in male horses and only 2 times in females.

Just a thought.

[DDT]

Stan

Well, I do apologize to you, the date on the referenced article was June 2008, I wonder if they have expounded on this?

DDT

[Pan Zareta]

The 2008 article doesn't dispute the lack of the diversity in the non-recombinant region of the domestic horse y chromosome which, again, is the only genetic factor common to all members of a 'sire line'. It does pose intriguing questions about the potential influence of the recombinant PAR region of the y, unchecked by x-inactivation, in defining success of individual sires.

[xfactor fan]

Here's a high level genetics question.

So there is a region on the Y that recombines with a region on the X.

Does this happen every time, or just ever once in a while.

If it happens every time would this be correct?


Using Raise a Native:

The RAN Y would be the standard Y from Native Dancer with a bit of genetic material from his paternal dam Geisha. This could have come from the X from Discovery, or the X from Miyako..

Then the Y that RAN passed on would be recombined with the Raise You X, which could be from Case Ace or Lady Glory.

So all the sons of RAN would have the same combination of Y + X, as RAN would only have the one X to swap genetic material with.

So all the sons of RAN would carry the RAN Y, which would be the standard Y with a bit of the Raise You X.

Then Exclusive Native would have the RAN, Raise You Y, but the Y he passes on would be recombined with a bit of the X from his dam Exclusive. So this Y would be EN + Exclusive.

And of course the flip side of this would be that the X that is passed on would have a bit from Raise You swapped on to the X from Exclusive.

So if there are performance genes in this section of the Y, all the sons of a stallion would have the same performance genes, but the grandsons would not. Which of course would invalidate the whole sireline argument.

[Pan Zareta]

So if there are performance genes in this section of the Y, all the sons of a stallion would have the same performance genes, but the grandsons would not.

No, because the PAR regions of the X and Y recombine during meiosis. Sons receive an exact copy of the non-recombinant portion of the y but the PAR of their y will be a mix of their sire's PAR-x and PAR-y. The more interesting aspect of the PAR is that it's active in both sex chromosomes in the male whereas females express the PAR of only one of their two x chromosomes, tho' not always the same one, due to x-inactivation.