I would like to address more fully what I consider to be an over-use of the term co-dominant. Please bear with me if I make some technical errors here, my biology degree was earned very many moons ago, but that's not the main reason I don't remember much from that period. (It was, after all, the late seventies. ) Okay, here's my point: Co-dominant should never have been used to describe the Salmon/Hypo trait. In scientific method, a thing called "Occam's razor" is usually used to help select a hypothesis. Simply stated, Occam's razor says that of two competing theories or explanations, all other things being equal, the simpler one is to be preferred. So if from the intial breedings of the hypo gene, if either co-dominant or simple dominant would describe the results, then simple dominant should have been chosen. (Theoretically, it should be clear from one breeding, but in the case of hypomelanism there are many other influences, such as naturally occurring "paleness" etc., which can mask the results, so several generations were required to clearly show the genetics: simple dominance.) In fact, unless there has been a radical change in the field of genetics since I went to school (which may well be the case), as I recall co-dominance is actually pretty rare, if it is being used in the sense of Mendelian genetics (XX shows the trait more than Xx). My point is that often a trait is governed by multiple alleles or variably expressive genes or God knows what. If a tall person mates a short person and the offspring has medium height, this is not the result of co-dominance. The closest thing I've seen to co-dominance in snakes is Tiger/ Super Tiger retics. I haven't followed the breedings very closely, but I question if even here the term co-dominant is appropriate. If the trait could be described as well by multiple alleles, wouldn't that be a simpler explanation? Maybe my confusion here is because I don't understand what people are referring to as co-dominant. If by co-dominant they mean Xxxx and XxXx is tiger, whereas XXxx, XXXx, or XXXX is Super tiger, then that would make sense. But again, if this is the case multiple alleles is a better description. My main concern here is that I see the term co-dominant thrown around a lot, as though the genetics are understood, when in fact the trait may be governed by something completely different.

[ Hide Replies ]

• Co-dominance and Occam's razor. - Barry M, Fri Apr 30 16:33:20 2004
• This is a great post... - Rainshadow, Fri Apr 30 17:17:10 2004
• Uughhhhh....you said "moon." Ugghh ugghhhh. - dmac, Fri Apr 30 20:48:47 2004
• Have a picture... - Barry Miller, Sat May 1 00:52:46 2004
• At what point did breeding boas require a masters degree....... - Hoppy, Mon May 3 18:19:45 2004