Yeah, The yellow coloration that comes in more intensely as certain snakes mature (as in the chins, throats and necks of normal, anery, and ghost corns you mentioned) and probably the extremely intense yellow amel nelsoni as well are likely prime examples of carotenoid retention from the prey they eat that is gradually stored. This also depends on certain individuals or bloodlines genetic predisposition for the ability to store these carotenoids too.

If you want to be thorougly puzzled, you should read some of the same articles I have on different pigment cells (chromatophores). You will walk away knowing much more, and much LESS than you ever thought you knew before..

Here's just a couple.....

http://vetherppath.hubpages.com/hub/Understanding-Reptile-Color-and-Correct-Color-Terminology

http://www.webexhibits.org/causesofcolor/7I.html

http://www.vmsherp.com/LCChromatophores.htm
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