Thursday, April 26, 2007
Averages, Absolutes, and Mistakes
It's interesting to talk to different people about genetics. They vary from the almost superstitious to the highly scientific. Most of us fall somewhere in between. Even if you feel that you are very scientific, you may have the feeling that odds are going to catch up with you. That's really more superstition than science (Gambler's Fallacy).
I believe that, excepting a spontaneous mutation, there are genetic absolutes. Genetic rules may appear to be broken from time to time. But I believe it's more a matter of either incomplete understanding or an erroneous judgment somewhere.
My grandfather used to tell a joke about three men who rented a hotel room together. They each paid $10, then it was discovered they were overpaid by $5 and were due a refund. The night clerk couldn't figure out how to give $5 to three men, so he kept $2. Each man paid $9 and the clerk kept $2 which adds up to $29, not $30. By listening to my grandfather weave the story, it sounded like a dollar disappears. Sometimes I think that our genetic logic is like that. We're looking at the wrong parts or adding up the wrong pieces of information.
First of all, we may have stated the absolute incorrectly. We may say that you can never get a broken from two solids. That's not true. You can never get a broken from two genetically solid rabbits. We consider a ruby-eyed white to be a solid, but that rabbit may indeed be genetically a broken and can produce a broken with a solid mate.
It sounds like a rule is being broken when you say that you got a broken from two solids. Instead, it's that the "rule" wasn't completely stated to begin with.
Sometimes, we get offspring that are "impossible" from the parents. Perhaps you get a black from a sable point and a Siamese sable. It is impossible to get a full color (C-gene) rabbit from two shaded rabbits (sable gene). Is this a miracle? No. That black is really a seal. Check the footpads and you'll find sepia instead of gray.
Other times, reviewing the pedigree gives no clue to what might be going on. The outcome is still impossible given the family tree. But there's no guarantee that each relative's information has been recorded correctly. I saw a lilac Californian on a pedigree the other day. Oranges and chocolate oranges could be very easy to mix up. Folks are often calling blue points, smoke pearl, even when smoke pearl is a genetic impossibility.
We also see breeders considering genes from the family tree that could not possibly have been passed down.
For example, if a great-grandparent carries the steel gene, but the grandparents were all "ee" colors (like tort, blue tort, sable point, and blue point), then the steel gene did not pass through. It can't jump down to the parents' generation. You may be seeing scattered white hairs or even silvering (that's the si gene), but it's not steel, which is dominant to the "e" gene. It can't hide under an "ee" color. Nor can genes literally skip a generation.
True, two steel genes can disguise themselves, but they'd do so as an "E" gene, not as "ee."
I've talked about runts before. These kits are born about 1 oz. instead of 1/2 oz. as most Holland peanuts are. They have very small ears, but normal bodies. My experience has been that most die by weaning, though some make it to adulthood as 2 lb. pets. How easy it would be to confuse one of these runts with a peanut and declare that the parents are both true dwarfs.
Although there are some absolutes, there are many more circumstances where we talk about averages. On the average, you will get a certain result 25% of the time or 50% of the time. You can even say that there's a 2/3 chance of a gene, if you can eliminate one of the possibilities by visual inspection. But remember that those percentages will hold most true in large samples. You CAN get a litter of 5 or 6 peanuts. It's happened to me. You can have a doe who has produced 33 kits and only 3 peanuts (instead of the 8 that would have been predicted in the beginning). You can get three fuzzy Charlies in a litter! But look at your statistics once you've had hundreds of births, and you'll see them approaching the predicted percentages.
You are probably familiar with this famous quote from Sherlock Holmes: "When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth. " But he also said, "It is impossible as I state it, and therefore I must in some respect have stated it wrong."
Laurie Stroupe
The Nature Trail Rabbitry “Home Of Grand Champions”
Precious Pet Rabbits
Affordable Web Site Design ¶ 9:29 AM
I believe that, excepting a spontaneous mutation, there are genetic absolutes. Genetic rules may appear to be broken from time to time. But I believe it's more a matter of either incomplete understanding or an erroneous judgment somewhere.
My grandfather used to tell a joke about three men who rented a hotel room together. They each paid $10, then it was discovered they were overpaid by $5 and were due a refund. The night clerk couldn't figure out how to give $5 to three men, so he kept $2. Each man paid $9 and the clerk kept $2 which adds up to $29, not $30. By listening to my grandfather weave the story, it sounded like a dollar disappears. Sometimes I think that our genetic logic is like that. We're looking at the wrong parts or adding up the wrong pieces of information.
First of all, we may have stated the absolute incorrectly. We may say that you can never get a broken from two solids. That's not true. You can never get a broken from two genetically solid rabbits. We consider a ruby-eyed white to be a solid, but that rabbit may indeed be genetically a broken and can produce a broken with a solid mate.
It sounds like a rule is being broken when you say that you got a broken from two solids. Instead, it's that the "rule" wasn't completely stated to begin with.
Sometimes, we get offspring that are "impossible" from the parents. Perhaps you get a black from a sable point and a Siamese sable. It is impossible to get a full color (C-gene) rabbit from two shaded rabbits (sable gene). Is this a miracle? No. That black is really a seal. Check the footpads and you'll find sepia instead of gray.
Other times, reviewing the pedigree gives no clue to what might be going on. The outcome is still impossible given the family tree. But there's no guarantee that each relative's information has been recorded correctly. I saw a lilac Californian on a pedigree the other day. Oranges and chocolate oranges could be very easy to mix up. Folks are often calling blue points, smoke pearl, even when smoke pearl is a genetic impossibility.
We also see breeders considering genes from the family tree that could not possibly have been passed down.
For example, if a great-grandparent carries the steel gene, but the grandparents were all "ee" colors (like tort, blue tort, sable point, and blue point), then the steel gene did not pass through. It can't jump down to the parents' generation. You may be seeing scattered white hairs or even silvering (that's the si gene), but it's not steel, which is dominant to the "e" gene. It can't hide under an "ee" color. Nor can genes literally skip a generation.
True, two steel genes can disguise themselves, but they'd do so as an "E" gene, not as "ee."
I've talked about runts before. These kits are born about 1 oz. instead of 1/2 oz. as most Holland peanuts are. They have very small ears, but normal bodies. My experience has been that most die by weaning, though some make it to adulthood as 2 lb. pets. How easy it would be to confuse one of these runts with a peanut and declare that the parents are both true dwarfs.
Although there are some absolutes, there are many more circumstances where we talk about averages. On the average, you will get a certain result 25% of the time or 50% of the time. You can even say that there's a 2/3 chance of a gene, if you can eliminate one of the possibilities by visual inspection. But remember that those percentages will hold most true in large samples. You CAN get a litter of 5 or 6 peanuts. It's happened to me. You can have a doe who has produced 33 kits and only 3 peanuts (instead of the 8 that would have been predicted in the beginning). You can get three fuzzy Charlies in a litter! But look at your statistics once you've had hundreds of births, and you'll see them approaching the predicted percentages.
You are probably familiar with this famous quote from Sherlock Holmes: "When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth. " But he also said, "It is impossible as I state it, and therefore I must in some respect have stated it wrong."
Laurie Stroupe
The Nature Trail Rabbitry “Home Of Grand Champions”
Precious Pet Rabbits
Affordable Web Site Design ¶ 9:29 AM
