Re: Re: HYB: spots (was another terminology question)
iris@hort.net
  • Subject: Re: Re: HYB: spots (was another terminology question)
  • From: C* C* <i*@aim.com>
  • Date: Wed, 27 Feb 2013 16:00:05 -0500 (EST)
Most humans with extra, missing chromosomes, or partial deletions, have severe heath affects,Almost all problems die before being born. Of the ones that live, deficits range from almost no problems, such as kleinfelters disease. These are extra copies of X chromosome, to some problems with life spans of only several months. Mongoloid children have an extra chromosome #21.
Different story in interspecies hybrids, as the ones that don't work just die in womb, we never see them. The ones that do work have similar genomes, and chromosomes. Could be one chromosome is silenced. Many other reasons why they work. But problems with sterility. In a mule we have 31/32 chomosomes. Presuming no paired homologues, a viable gamete would have probability of (1/2)to power of 32 x (1/2) to power of 31. But since it has happened,There must be some paired homologues, increasing probability of a viable gamete. And having some paired homologues would make sense seeing their positions (donkey and horse) on the evolutionary tree.
Now, as to crossing over of genes. Probability of a gene crossing over is related to it's distance from the centromere. Only less then 50% if gene is located within 50 map unit of centromere. Most genes are well past this. So even if a gene is right beside centromere, it would still cross over 1% of the time. So if the appropriate gene from pumilla paired with it's corresponding one on a TB chromosome, there would be crossing over in more then 1% of the time. So at least one in 100 seedlings. And this is the absolute mimimum. We have exceeded these numbers by some astronomical amount,. No crossing over, so conclusion is genes can't pair. If they could pair, there would have been crossing over. So it hasn't happened, because it can't happened. If it could of, it would have.
Of course having said that, there is always something very strange happening with mother nature. But if this happened, it wouldn't be a very low probability event, it would be a theoretically impossible event. 

Chuck Chapman

-----Original Message-----
From: Linda Mann <lmann@lock-net.com>
To: iris <iris@hort.net>
Sent: Wed, Feb 27, 2013 2:03 pm
Subject: Re: [iris] Re: HYB: spots (was another terminology question)

You did say they would die or have major health defects (humans).
Don't know if they tried to breed the mule hybrid children.

On 2/27/2013 11:09 AM, Chuck Chapman wrote:
My main point was in regard to producing fertile offspring, not about 
if

they could produce living offspring.


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