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(05-22-2012, 03:34 PM)Twitchin Kitten Wrote: They probably have equipment now that can get a good look at how big his heart is without waiting for his demise.
Everyone thinks it's the Stallion that makes the champ, but those who have any knowledge of horses know it's the mare. 80% of the foal is the mare. The stallion is only a sperm donor.
That's not true Dear. It is a combination of Both acting together. What you are seeing here is just one indicator, of which there are countless.
For example this X Chromosome result would still be the output of both male and female genes. I'm not sure if this is a final form of hetrozygosity, or homozygosity, but I suspect the former. Hetrozygosity would be an 'xy' trait from both parents, and homozygosity would be one 'xx' and one 'yy' trait. The best example of this can be seen in Balanced Polymorphisms. And while the best known one is the Sickling trait, there are many other examples that are not so deadly.
And if it were to be an 'xx' trait, just what trait would give the recipient a 'select advantage' over the rest of the breeding population? And note that these horses with over large hearts do not die from the result, but rather have a select advantage for passing on these genes to other generations. In other words, it is a distinct plus for the success of the species. And I have not found any example of cases where other offspring develop other manifestations that lead to their demise, or weeding out, as you will see with Sickle Cell Anemia, Cystic Fibrosis, or other examples.
I know I am perhaps not being so clear here, but as the saying goes about 'taking two to tango', this case would also apply to it.
If a much larger heart wins races, and it is selectively bred for that purpose, it will be something breeders will shoot for. And if it doesn't present a significant danger for a large percentage of offspring, it will become part of the breeding population's success in the future. But it will require both partners.
(05-22-2012, 07:16 PM)LKTraz Wrote: I'd say IHA likely has a large heart but Secretariat was a freak of nature. The odds of another like him are astronomical......genetically speaking.
The(y) simply need to do a CAT or MRI on him to get a measurement (minus the weight) and see how he compares.
IHA does have what it takes. Now we just have to wait and see if he delivers.
One thing is certain: if it is successful, and large hearted horses consistently win, you can bet it will no longer be a 'freak' of nature. It will be the 'norm' in the business. In other words, humans will be tinkering with genes, just as they have been doing for thousands of years now. How do you think the 'Domestication of Plants and Animals' came about so successfully. I did a good deal of graduate work in this before switching from anthropological anthropology to physical anthropology. The evidence of New World plant manipulation is well documented, and while plants were the main thing in South/Central America, the Middle East has all sorts of examples where animals were genetically manipulated over the last 10-12 thousand years.
That is what is going to be going on here in the future. Soon almost every thoroughbred will have a super large heart, and they will be breaking records that were not thought of before. You just wait and see here.