Saturday, June 14, 2008

Line breeding

I read hundreds and hundreds of books while I was growing up. Somewhere among all the Black Stallion, Hardy Boys, Hornblower, and of course Tolkien books, I read a book by Albert Payson Terhune called Lad: a dog, a (somewhat anthropomorphized) true story about the life of Sunnybank Lad, a collie. From that moment on, I wanted a collie and was going to get one as soon as I could. And I did. My ex-husband David and I weren't married yet and couldn't afford an expensive dog, so I called a local breeder and asked about pet quality puppies. She didn't have any puppies, but she had a two year old that we could come and look at. It was love at first sight for both me and Robin.

While talking to her, I was completely flabbergasted when she started explaining her breeding practices. She "line bred" which meant selectively inbreeding the dogs with the best characteristics to try and reproduce those characteristics...I don't remember exactly how much, but Robin's mother was very closely related to his father. I had recently taken a genetics course at UC Davis, so I was even more shocked. She didn't seem to understand that, though she was trying to consolidate the genes that resulted in a champion's conformation, the puppies were far more likely than average to receive two copies of a deleterious recessive gene.

I googled line breeding and got a lot of dog breeders who more or less said the same thing. They defined inbreeding as the breeding of relatives not separated by more than one generation. Line breeding is used to concentrate the good qualities of an ancestor. They seem to justify line breeding because they use it to "set" characteristics that they want and weed out the genetic defects in a line. The genetically defective dogs are sold as pet quality if they are not "too" defective, or destroyed. Personally, I think that purposefully creating defective animals is inhumane and immoral. That said, I can understand that for certain rare breeds, line breeding may be the only option.

Of course, line breeding isn't limited to dogs. I pointed out that genetic relatedness is one of several hypotheses about why champion racehorses often have major problems in a previous post. Line breeding occurs in all domestic animals.

Then I happened upon this guy. He justifies line breeding because it is sanctioned in the bible, starting with Adam and Eve. If you take the bible literally, Adam and Eve's children would obviously have to breed with each other (this wouldn't be line breeding according to the dog breeders' definition - it would be inbreeding). He then points out that everyone would be 50% related to Adam and 50% related to Eve. This doesn't seem to faze him.

He then goes on to state that Noah and his progeny were God's line breeding program and calculates out their percent relatedness. Apparently God chose Terah's blood to concentrate and create the Jewish race. This guy is a Pony of the America's (POA) breeder. I have a special fondness for POAs, as I had one (Paleface) when I was growing up. I hope they're not all being bred by morons.

My mother took this photo just after my son was born. Robin was a lovely dog.

And remember. If it doesn't drool, it's not a collie.

1 comment:

the chaplain said...

I'm not a geneticist, but my lay knowledge is good enough for the idea of line breeding, particularly done over a long period of time, to give me the willies.