Foundation pedigrees

[dublino]

"Estimated mathematically" doesn't sound very scientific?

I thought science was definitive? And not estimated?

Sounds like you don't really know and are covering your base by giving an estimated range?

Sounds like this theory is bust wide open?
Sounds like the only way to verify is to take a genetic sample of every horse in each of the 5 generations of a horse and compare it against a subject horse?
I doubt this has been done for any 1 horse let alone a sample large enough to prove and theory???

[Pan Zareta]

"Estimated mathematically" doesn't sound very scientific?

I thought science was definitive? And not estimated?

Sounds like you don't really know and are covering your base by giving an estimated range?

Sounds like this theory is bust wide open?
Sounds like the only way to verify is to take a genetic sample of every horse in each of the 5 generations of a horse and compare it against a subject horse?
I doubt this has been done for any 1 horse let alone a sample large enough to prove and theory???

Sounds like your knowledge of science, especially genetics, is pretty limited.

[xfactor fan]

stancaris.

Let's look at Raise a Native and one gene.

Native Dancer was gray. RAN chestnut, no gray gene. So RAN got 0% of the gray gene, and most likely, a chunk of chromosome and genes located next to the non-Grey carrying chromosome that was passed on from Polynesian.

Working back one generation Geisha (gray) passed on her gray gene and the genes around the gray gene to her son Native Dancer--100%.

Gray foals of Native Dancer will have the gene from Geisha 100%. Non gray will have 0% from Geisha.

More genes in the sample, the closer the percentages come to a bell curve with very small number at either end, and the bulk of the sample falling in the middle. With the ends being all from one parent, the middle being a mix of genes from both parents.

In human terms, think jockeys on one end of the human height spectrum, and NBA players on the other. Clearly there are humans that are under 5ft tall, and others that are over 7ft tall. However most fall in between.

[dublino]

Sounds like your knowledge of science, especially genetics, is pretty limited.

All I ask is for your Science and Theory to be backed up with fact, evidence or proof?

Not much to ask?

Claiming my knowledge is limited doesn't prove your theory.
My knowledge might be limited and I'll tell you why, experts like yourself haven't shown me proof of their Theories.

So my ignorance is based on your lack of facts.

[stancaris]

Pan Zareta: A fourth generation ancestor will contribute on the average 6.25% of his genes to a horse in question. You stated something like the following: In the vast majority of cases this can vary around 2% under or 2% over the 6.25 number and you listed the range as approximately 4-8%. I find that mind boggling. Do you mean to say that mathematically it is very unlikely or is a very rare occasion that a 4th generation ancestor will transmit 10% of his genes to the horse in question? Thats only approximately 4% more than the expected 6.25%. I would think that with all the spins in the process of meiosis that the deviation of the percentages would vary much more than 2% in either direction.

According to the way I am interpreting the above it would be a very lucky turn of meiotic events for a fourth generation ancestor to send 10% of his genes to the horse in question and thats only 4% more than the expected amount of genes.

[Pan Zareta]

Sounds like your knowledge of science, especially genetics, is pretty limited.

All I ask is for your Science and Theory to be backed up with fact, evidence or proof?

Not much to ask?

Claiming my knowledge is limited doesn't prove your theory.
My knowledge might be limited and I'll tell you why, experts like yourself haven't shown me proof of their Theories.

So my ignorance is based on your lack of facts.

Meiotic recombination aka: crossing-over and its implications for how much DNA is received from grandparents and more distant ancestors is explained in the genetics section of most basic secondary (preparatory) level biology textbooks and has been for about the last 50 years.

Go look it up yourself.

I don't spoon-feed trolls.

[Pan Zareta]

Pan Zareta: A fourth generation ancestor will contribute on the average 6.25% of his genes to a horse in question. You stated something like the following: In the vast majority of cases this can vary around 2% under or 2% over the 6.25 number and you listed the range as approximately 4-8%. I find that mind boggling. Do you mean to say that mathematically it is very unlikely or is a very rare occasion that a 4th generation ancestor will transmit 10% of his genes to the horse in question? Thats only approximately 4% more than the expected 6.25%. I would think that with all the spins in the process of meiosis that the deviation of the percentages would vary much more than 2% in either direction.

According to the way I am interpreting the above it would be a very lucky turn of meiotic events for a fourth generation ancestor to send 10% of his genes to the horse in question and thats only 4% more than the expected amount of genes.

Stan, this source cites some odds in regard to chances of no/excessive DNA from various ancestors in the human. The odds will be slightly more against it in the horse simply because there are more chrosomomes involved. But as you can see they decrease exponentially with each generation back.

[stancaris]

Pan Zareta:

Thanks for the interesting link. According to the data presented your chances of not getting any of a 4th generation ancestors genes is 1 in 64 or 1.56%. Looking at it another way you can say that the chances you will get some DNA from a 4th generation ancestor is very favorable at 98.44%. It is extremely unlikely that you get zero DNA from a 4th generation ancestor. Almost 99% of the time you will get some of that ancestors genes (In Humans).

Question: why does the presence of more chromosomes as is the case with the horse (32 pair) make it more likely that a horse will get zero genes from a 4th generation ancestor?

[Jeff]

Nearly a 100% certainty that all ancestors in the 4th generation will pass along dna to the foal. That's the scientific evidence.

[Pan Zareta]

Nearly a 100% certainty that all ancestors in the 4th generation will pass along dna to the foal.

That's the statistical probability. The remark that set this off was "It's quite possible for an individual to have no genetic material from a 4th or 5th generation ancestor", the 4th being the nearest generation at which complete loss of contribution might reasonably be expected to be observed, if rarely. "Quite possible" does not equal "occurs frequently". Zero DNA from a 4th gen. ancestor is just one of the myriad possible outcomes from 4 or more of the 'shufflings' of DNA between chromosomes that occur during meiotic recombination. The main point of the remark was to illustrate the fact that the exact contribution from any single ancestor in the 2d gen. and back cannot be determined simply by dividing 100 by the total ancestors in that generation.

Stan, I said that the odds will be slightly more against (i.e. it's less likely) a horse having zero DNA (not "genes") from a 4th gen. ancestor than a human. More chromosomes mean more discrete recombination events have to disfavor an ancestor to completely eliminate its contribution.

For anyone doubting the validity of my remarks above, see Variation in actual relationship as a consequence of Mendelian sampling and linkage and related citations.

[stancaris]

Pan Zareta:

Thanks for the links above. I find them very interesting and understandable.

For further clarification lets look at Verrazano as an example. He is inbred 4X3 to Mr. Prospector. According to the data you posted in one of your above posts he could have gotten anywhere from approx 4 to 8% of Mr. Prospector's DNA when Mr. Prospector appears in the 4th generation. If you just reduce it by 1/2 in each generation you get 6.25 (which is approx 2% over or under that range)

Verrazano has Mr. Prospector in his third generation on the dam side which means he could have received anywhere from around 9 to 16% of Mr. Prospectors DNA from that 3rd generation position. If you just reduce it by 1/2 for each generation you get 12.5% which is around 3.5% over or under that range).

If he got the highest amount of DNA from Mr. Prospector it would be around 24% (8% from the fourth generation position on top of the pedigree and 16% from the third generation position on the bottom). Verrazano could contain 24% of Mr. Prospectors DNA.

If he got the lowest amount of DNA from Mr. Prospector he would come up with around 13% (around 4% from the 4th generation position and around 9% from the 3rd generation position.

At best Verrazano could be around 24% Mr. Prospector and at the least he could be 13% Mr. Prospector. If you just did the reduce by 1/2 trick he comes up with 18.75% Mr. Prospector which is around 5% over the worst case or 5% under the best case scenario.

One problem with the above could be that some of the DNA that was transmitted at generation 4 could be identical to some of the DNA that was transmitted at generation 3. In that way you really do not get that 24% figure but somewhat less than that.

Your point was that its not just simple math from generation 2 on back. Its not just a definitive 25% from 2nd generation, 12.5% from the third generation, and so on. However, the differences are not really that huge when looking at Verrazano above because in total he could only be around 5% above or below the 18.75% figure when we look at the 4X3 inbreeding to Mr. Prospector.

[Pan Zareta]

One problem with the above could be that some of the DNA that was transmitted at generation 4 could be identical to some of the DNA that was transmitted at generation 3. In that way you really do not get that 24% figure but somewhat less than that.

No, it's still the same amount, still Mr. P. DNA, just in duplicate, which is what inbreeding is all about.

However, the differences are not really that huge when looking at Verrazano above because in total he could only be around 5% above or below the 18.75% figure when we look at the 4X3 inbreeding to Mr. Prospector.

If the amount of autosomal and pseudo-autosomal DNA Verrazano rec'd. from Mr. P. is within the confidence intervals that's quite correct.