New Study on the Y Chromosome

[vineyridge]

http://horsetalk.co.nz/2013/04/05/limit ... V7uVTfE1SO

They concluded that Eclipse had a mutation in the area that was studied. Actually it wasn't Eclipse, since King Fergus didn't get it. It was more likely PotO8os or Waxy or Whalebone.

The story is fascinating. Now to go off and read the actual study which is in PLOS.

[Patuxet]

Thanks for posting this.

[siegy]

http://horsetalk.co.nz/2013/04/05/limited-genetic-diversity-in-stallions-revealed-in-study/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+HorsetalkconzHeadlines+%28Horsetalk.co.nz+Headlines%29#.UV7uVTfE1SO

They concluded that Eclipse had a mutation in the area that was studied. Actually it wasn't Eclipse, since King Fergus didn't get it. It was more likely PotO8os or Waxy or Whalebone.

The story is fascinating. Now to go off and read the actual study which is in PLOS.

tx: for posting......,

Siegy,

[xfactor fan]

In short, all stallions from the Whalebone line have the same Y chromosome. Every other line tested has a different Y chromosome.

[Pan Zareta]

In short, all stallions from the Whalebone line have the same Y chromosome. Every other line tested has a different Y chromosome.

The Y haplotype found in all descendants (multiple breeds) in 'tail male' of Whalebone differs from that found in the other descendants of Eclipse (as well as in descendants of Matchem & Herod) by a single base pair deletion and is believed to represent a 'mutation' in Pot8os, or Waxy, or Whalebone. In this case the mutation may have been in the form of an X to Y gene conversion. Among the many breeds tested six Y haplotypes were documented, the single haplotype that survived domestication, four primary variants thereof, and one secondary variant which is the type found in Whalebone's tribe. The full report is at
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0060015

[vineyridge]

Makes one wonder what the mutation controls that seems to have been so beneficial for breeding for speed. Since it's certainly clear that the Whalebone tribe has been taking over TB race breeding ever since it appeared.

[vineyridge]

Did anyone else notice that the orginal Y chromosome that survived domestication didn't seem to be present in the lines that made racing that were studied. If the color coding in the article is used, the "yellow" variant was found in 100% of the standardbreds that were studied; the QH is mostly yellow with some red (Whalebone); and the TB is mostly red with a touch of Yellow. The domestication color is blue, and most arabians are blue with a small percentage of yellow.

So it looks as if the yellow variant is the one that has been performance selected for speed--and then the red variant came from that.

[Pan Zareta]

Did anyone else notice that the orginal Y chromosome that survived domestication didn't seem to be present in the lines that made racing that were studied. If the color coding in the article is used, the "yellow" variant was found in 100% of the standardbreds that were studied; the QH is mostly yellow with some red (Whalebone); and the TB is mostly red with a touch of Yellow. The domestication color is blue, and most arabians are blue with a small percentage of yellow.

So it looks as if the yellow variant is the one that has been performance selected for speed--and then the red variant came from that.

One of the main purposes for bringing the 'Oriental' (Middle Eastern) blood to the British Isles was to put some bottom (stamina) on the native stock. And there is not even a hint of speculation in the report as to whether any of the Y chrom. variant confer any functional advantage although there is plenty of logical and reasonable commentary therein on the natural and artificial forces that make the 'contraction' (bottle-necking) of sire lines in the domestic horse an inevitable result.

I seriouly doubt that the QH HT distribution reflected in the report is accurately representative. If you look at the most popular sires, racing and working, over the last two decades the breed is as heavily bottle-necked under Whalebone as the TB, if not more so. It's somewhat surprising that they had three tail male descendants of Traveler (ped. unknown). Even a single QH sample tracing in tail male to the Byerley strains credibility and may have something to do with the fact that the allbreed db was one of their cited online reference dbs.

[vineyridge]

I noticed that they used allbreed, which is notoriously unreliable. I wonder why they didn't ask for access to the AQHA database.

[xfactor fan]

Since all the Standardbreds trace back to Hambiltonian 10 (Rysdyk's Hambletonian), and this line traces back to Messenger and then back to the Darley Arabian, not through any of the Eclipse sons, and not via Whalebone, yellow or H2, would be expected. If they found any of the other versions, it would have to be either a new mutation, or a fence jumper.

There's some dispute about Messenger's pedigree. Or about his breeding. I've seen claims that he was part some sort of trotter. Which is why he made such a strong contribution to the Standardbred.

[vineyridge]

I know they took Messenger out of the GSB at one point. Don't know if they ever put him back in.

[Pan Zareta]

I know they took Messenger out of the GSB at one point. Don't know if they ever put him back in.

As first entered in the GSB 1791 *Messenger is remarked as "sent to the United States". To the best of my knowledge his record as shown there has never been removed and was revised only to more specifically identify his dam. Wallace (Horse of America Chpt.17 ) questioned the authenticity of American advts. and ctfs. for *Messenger. Harrison (Early American Turf Stock 2:264) found the evidence for his pedigree to be probative but could not confirm claims from NorthAm records as to breeder and previous owners. In Fig. 4 of the equine Y chrom. report under discussion he is shown in the lineage of Rysdyk's Hambletonian all of whose sampled descendants in tail male are reported to have HT2.

The QH samples attributed to the Byerley may have come from contemporary descendants of Peter McCue, still active in tail male in the QH at very low frequency. The abdb and SportHorse db both show his topline terminating at the Byerley notwithstanding the fact that his pedigree as first recorded by the breeder in his personal records places PMcC under the Godolphin. Contemporary QHs attributed, rightly or wrongly, to the Byerley via other sire lines are near impossible to find.