markers

[Mendel's Balls]

Someone pointed out in another thread that the term "marker" indicates a separate gene that indicates the presence of the gene you are interested in.

I'm not sure that "marker" is the best term here as it might be the pied gene it's self that is sporadically showing through in some of the hets.

A genetic marker is indeed another gene or DNA sequence that is associated with another gene. I doubt anyone has created a linkage map for ball python genes. I know no one has created a physical genetic map since not one reptile geneome has been sequenced yet.

People on here tend to use the term "marker" as if the heterozygote genotype itself shows through in the animial's phenotype. This is more like an example of incomplete dominance or penetrance.

I am new to the ball python world but I wouldnt put to much faith in the these so called "het markers". For example, if I was breeding pied I wouldnt "throw away" those 66% or 50% possible het pieds that lacked a het maker.

I checked the site above and looked at the het marker guide for pied and maybe its just my untrained ball python eyes but I wasnt very convinced......animial looked pretty much like a wild-type to me. In one of the pics of the same guide the author said the animial was a "also a ringer" and I can maybe see where he gets that but I think he's stretching there.....so I am inclined to say all of this is wishful thinking like Adam said.

The author of the above site lists that here are the phenotypic markers for het pied

1. Black striping down BOTH sides
2. Clear belly between the stripes

Before this he stipulates that most of them with this marker turn out not to be het and instead complete normals.

Lets assume there is something to this phenotypic marker ....I'll offer another explanation of why it might be "seen" in het pied..... .maybe it's caused by another gene that is on the same chromosome for the pied gene.......Then it would fit the definatiion of a genetic marker. Even then though it usefulness for differentiating the genotype of 50%/66% het from homozygous complete normals would only be as good as how close it is on the chromosome to the pied gene. This is because even linked genes undergo recombination through chromosome cross-over in meiosis.

See http://www2.dpi.qld.gov.au/beef/2244.html

See the section titled "Exploiting Major genes with Genetic Markers"

But before we start take any explanation seriously though.....I think someone has to show definatively it really is significant, not just wishful thinking....