Not to argue with The Institute for Herpetological Research, but fraternal twins are in fact possible and occurring contrary to what they have written. To debunk the idea that there are no occurrences of identical twins in both, we have all seen Siamese twins (non-dizygotic) with snakes and dragons. This is actually an incomplete split while forming identical twins. Since we have seen failed attempts, we know it is possible and is in fact occurring successfully without our full awareness of what has occurred. The idea that they are actually two animals that somehow commingled is not probable because they both have active immune systems that would react to this no matter how close these siblings appeared. They would obviously have a shared cardiovascular system.
If the opportunity presents itself, I will take a tissue sample of a Siamese pair and a control pair. Have them genetically mapped and do a simple comparison. While I feel this is overkill, if I get the chance and the lab can deal with a lizard (we do mostly birds) I will do it and post my results.
The other question was toward double-yoked eggs. In fact rapid ovulation is an inherited trait. The chicken industry is the most investigated research on animal development and breeding in the world. More then humans! Rapid ovulation is bred into the lay chickens. I know someone out there is going to make a statement about how chickens are not lizards. How humans are not chickens. Sorry to break it to you, but we share a very similar reproductive system no matter how visually different it may appear we are much more similar then different. This is a very complex issue but essentially we all share the same base code. Our own code is based on fish and everything in between. Get down to the cellular level and we share so much with a protozoa it would scare you (think mitochondria).
What can be bred into lizards and what cannot? EVERYTHING can be bred into or out of any animal as long as its genetics support it. That last part simply means that you cannot breed a horse’s head onto a snake. However, with enough work, you could probably increase a snake’s head over 10X its present size. Normally nature would weed out this defect, but if we care for the animal and breed it manually, we can increase its head size to whatever proportion or shape we want by “selective breeding” and “line breeding”. Why someone would want to breed a huge head on a snake? I wouldn’t but people out there find reasons to breed horrible defects into animals for aesthetic purposes (Bull Dogs etc etc).
This leads into “what is an attractive Bearded Dragon”? Most people seem to be breeding color. While this is a great addition to an already sound animal, we should not ignore the basics. Symmetry should be preserved. What makes a face attractive? What tells a flower where to place its petals? It is best summarized in the Fibonacci sequence and the Golden Section. This is a simple math equation that holds symmetry in place. It explains why a blood red dragon that is selling for $400 somehow turns you off. Subconsciously, you are aware of symmetry expressed in this equation (phi= 0•618034). Most of dragon symmetry, if all other parts are equal would be pattern. If we lose symmetrical pattern the dragon will be unappealing overall no matter what color we breed into it. Even an apparent non-symmetrical pattern that follows the Fibonacci rules are In fact patterned and apparently attractive and desired (the term ugly but cute). I really can’t get into all of this and keep the post under 20 pages but overall pattern, overall body symmetry and size is what should be bred into an animal and should not be sacrificed to color mutations.
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