Originally Posted By: Orac
This seems to be your area ImagingGeek so I will ask some questions because your BLACK/WHITE answer for a scientist always gets my attention

I believe you adhere to the strict evolution teaching of the five recognized causes of biological evolution are:

1. mutation
2. migration also known as gene flow
3. random genetic drift (small populations)
4. non-random mating
5. natural selection

I'm not sure what you mean by "non-random mating"; that certainty is not an accepted element of evolutionary theory. Indeed, sexual reproduction is the exception to how organisms reproduce (the bulk of life on earth reproduces asexually).

There are more mechanisms than those - horizontal gene flow, genetic recombination, etc, etc, etc. And there are mechanisms which are not yet proven to be involved - but which could be. Kin/group selection, for example. The fundamentals of evolution have not changed much since darwins time, but there are a handful of new mechanisms which have been discovered since then, and a few which have question marks around them.

Originally Posted By: Orac

So perhaps if you can comment on these


Epigenetics are inheritable changes in gene expression which does not modify the underlying genetic material. Epigenetic changes usually only last a couple of cellular generations. In metazoans [animals] most (perhaps all) epigenetic changes are "reset" in the embryo - i.e. they are not inherited parent->child. Thus they are unlikely to have a significant evolutionary effect, as they are not inherited over generations.

There is a caveat to this - some "simpler" single-celled organisms appear to pass on some epigenetic changes from generation-to-generation. These epigenetic changes remain quite plastic, so their effect on evolution would likely be weak (compared to mutation, which is permanent), but they could, in these rare cases, be inherited and thus have a evolutionary effect.

Originally Posted By: Orac
Biased gene conversion:

Gene conversion is a form of mutation, and would be accounted for in the "mutation" stuff I mentioned earlier. Gene conversion is simply an error in genetic recombination (which occurs during sperm/egg production) which results in either exchange genetic between alleles/gene, or which produces an unbalanced exchange of DNA between two loci. Similar mechanisms also occur in non-sexually reproducing species; for example, sometime bacteria take up DNA for food and accidentally cross-over with it, thus converting a part of their genome to whatever was encoded in the 'food'.