MrDarwin

Regarding degree of genetic divergence, I might point out that chromosome numbers vary within this plant group, which they do not among dog breeds (nor for that matter between dogs and wolves).

Douglas, I'm willing to look this information up but before I do, I have to ask just what you think it will mean. If these plants have diverged more (or less) than dogs, what significance does it have? What degree of genetic divergence would indicate that two organisms are different "kinds"? Because I predict that whatever answer I give you, you will turn around and say, "well, that's just the amount of genetic variation that's allowed within kinds."

MrDarwin

I'd like to point out here, as I have had to several times in the past, that creationists define "macroevolution" quite differently than do evolutionary biologists. This lack of agreement on basic terminology is one of the stumbling blocks to rational discussions between the two groups.

Peez

I am not aware of any evidence that any organism can preferentially generate mutations that are beneficial to the organism. I have asked mturner for such evidence, but mturner has not yet provided it. Also lacking is any hypothetical mechanism that could produce such mutations. What has been found is that some organisms, when under stress, may have higher mutation rates. Such higher rates may be due to the DNA replication machinery not working as well under stress, or their may be some mechanism that works to decrease the efficiency of DNA replication so that more mutations occur. There is also data that suggests that some parts of the DNA of an organism may have higher mutation rates than other parts, and the mutation rates in some parts may be increased preferentially. What is utterly lacking is any indication that a given mutation is more likely to be useful to the organism under stress. Each mutational event is random with respect to functionality (but not entirely random, of course, since DNA is a chemical that tends to act in certain ways, like any other chemical). By increasing the mutation rate, especially if this can be done at a particular part of the DNA, the organism increases the number of beneficial mutations simply because the total number of mutations is increased (the proportion of mutations that are useful is not apparently changed).

Peez