Extent of Mutational 'Elasticity'

Hi all,

I am new to this forum, and also to this level of the ID-creation-evolution debate.

A year ago I set myself the task of plumbing the depths of the debate to ascertain, if I could, the truth about this issue (bearing in mind that my field is theology, not science).

To this end I would like to pose a series of questions, and would appreciate input from all sides.

My first question relates to the extent and depth of which mutations are capable, that is, of genetic ‘elasticity’, as it were. Namely: Is there any known process or element in the genetic make-up of animal organisms, or else anything within biology, that would actively stop or act as a barrier to so-called 'macroevolution’. In other words, anything known to genetics that would prevent transformation or mutation from one animal category to another, i.e., any process that would preclude, for example, an ape-like form evolving into a human being, a dinosaur evolving into a bird, and so forth.

It goes without saying that adaptation occurs on a lower level, eg, adaptation can result in different types of finches within the finch species, or else different breeds of dog within the dog species, etc. I believe all sides are agreed on this (so-called 'microevolution').

The crux of the debate, of course, is whether organisms can adapt significantly beyond this, from one animal to a different animal form altogether (ie, so-called 'macroevolution'). Thus I would be interested to know if there is any known genetic barrier that would actively prevent this larger step to a different animal form.

As a layperson, I am struck by the inventive adaptations within the dog family (eg Great Dane compared with Maltese, etc.) Looking at this level of inventiveness, it might seem that the inventive step from one to another animal type as such is not unreasonable.

However, the creationist counter-argument is, I believe, that DNA make-up is like a computer software programme, and that it cannot develop outside of its basic programming. Thus a cat could never evolve into a dog, etc.

Of course, I have also heard the evolutionist argument that two different genes can merge and share their differences, resulting in a new genetic direction, and in this way new animal classes develop.

I hope I have stated the science correctly, as per above.
So then, I would greatly appreciate all input on this point.

Regards,
Greg