Reptile & Amphibian Forums

This is a continuation of a threat that started under the title of The Scientific Method and "Extreme Hypos".

theselectserpent posted:
>Well so much for my thread but oh well this is also a facinating questions. Bob, first of all as not to confuse people your first post said during mitosis and your second correctly stated meiosis. Meiosis is the process by which gametes (eggs and sperm) are formed, the ONLY haploid cell in the body. You also said two sets of chromosomes which implies 4 chromosomes. It is ONE set (2 chromosomes, diploid)that divide into 2 single (haploid) chromosomes to form the single chromosome gamete. Your proposal of gene linkage is a good one along with what I have been throwing out there with crossovers during meiosis lending to phenotypic diversity in all animals. Crossovers for example are the reason we get 16 differant genotypes in a DH breeding. Anyway thanks for the thoughts and it is worth thinking more about.

I have not perceived evidence for crossovers in the posts about the extreme Honduran milks or the gophers in the original thread. If there was only one pair of chromosomes in a milk snake's cell nucleus, I'd agree with the post I copied over (above). But there are 18 pairs of chromosomes in a normal adult milk snake cell. And a normal sperm or egg has one chromosome from each pair, or 18 individual chromosomes. Which means there is a better than 90% chance that two gene loci are not on the same chromosome. IOW, both crossovers and chromosome assortment during meiosis increase genetic diversity among the sperm and eggs.

"Crossovers for example are the reason we get 16 differant genotypes in a DH breeding." When someone writes "the reason", I assume he means the one and only reason. Crossovers are required when two loci are on the same chromosome. But chromosome assortment is the reason for all the different genotypes when two loci are on different chromosomes. And exactly the same genotypes are produced from crossovers as from chromosome assortment. That makes linkage very hard to find without mating a double heterozygous snake to a double homozygous snake.

So I want to know what evidence was presented that eliminates the possibility of chromosome assortment and requires crossovers. This can be in either the albino gopher snakes or the extreme Hondurans (preferably both species).

Paul Hollander

First of all Paul thanks for straighting out some of those explanations as this setting (the forum) is very hard sometimes to get what is your head into words that EVERYONE will understand, next to impossible! My only point with the extremes is that maybe it is simply a phenotypic differance among hypo-M's caused by the genotypic differance along the chromosome (or chromosomes) that might incorporate many loci contolled by the hypo-M gene and that the differant genotype would be caused by crossovers which as you stated helps with genetic diversity. I'am saying that I think we often look to much at ONLY the hypo-M gene and NOT at the vast array of other genetic info that gives the snake its phenotype. Again, that is my hypothesis in this process whether it be right or wrong we don't have enough info to go beyond that point as it only leads to conjecture. Too many peolpe argue the way they WANT it to be and I'am only saying that if we all work together on this and don't jump to conclusions we can probably discover more at a faster rate. Thanks again Paul for your input on this and keep in touch.

Matt Woodhall