Talk:Molecular clock

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Article Grading: The following comments were left by the quality and importance raters: (edit · history · refresh · how to use this template) rated top as high school/SAT biology content - tameeria 14:51, 17 February 2007 (UTC) This article could use figures and references. Also, it should include several sections: The evolutionary molecular clock and molecular clocks for circadian rhythms and other temporal cycles in cells and organisms (e.g. hormone cycles in mammals, seasonal flowering time control in plants). - tameeria 19:04, 18 February 2007 (UTC) What you seek is a different article. Something that should link out of Chronobiology. Shyamal 10:27, 19 May 2007 (UTC)

[edit] Use of non-coding DNA

The article has information on the problem of non-equal clock rates due to differences in the selection pressure. There is the alternative approach of getting over the problem of selection pressure by choosing sequences which are presumably non-coding and therefore untouched by selection. Randall L. Small, Julie A. Ryburn, Richard C. Cronn, Tosak Seelanan and Jonathan F. Wendel 1998. The tortoise and the hare: choosing between noncoding plastome and nuclear Adh sequences for phylogeny reconstruction in a recently diverged plant group. American Journal of Botany. 1998;85:1301-1315. [1]. Why is this not more popular ? (My own guess is that this is perhaps because it is easy to fish functionally equivalent sequences across two species, but not so easy to find two "equivalent" non-coding regions). Perhaps this can be covered in the article. Shyamal 03:07, 13 May 2007 (UTC)

[edit] Schwartz's fringeness and confusion

I find the Schwartz's references and links rather... bad. Whereas there well may be some challenges to molecular clock, he, Uatu only knows why, equates that with a challenge to "darwinism" (!), and based on that makes a whole illogical opposition while proposing his neo-saltationism. Even if we maintain that the molecular clocks are steady, it does not mean that the adaptive evolution (which is only a minor part, that presumably does not affect the clock meaningfully) would be steady, or that phenotypic change would also need be steady, with all the mutations causing only similar degrees of phenotypic change. I'm not quite sure of what I'm going to say, but I think I've read that he proposes that only a single mutation could have originated the eyes without natural selection, based on the fact that, in a few eyeless fish species, a single mutation can make they develop eyes - which is only possible because the genetic recipe for the eyes was there first, only was "deactivated" when they adapted to dark waters, so it's still there to eventually be brought back. Besides that, he proposes that orangutans are our closest relatives, not chimps. The close kinship with chimps is "only" based on genetic evidence. (The morphological similarities between orangutans and humans can also be accounted with more conventional explanations, such as the idea that humans left from an arboreal lifestyle and retained/refined the bipedalism of an orangutan/gibbon-like ancestor, while chimps and gorillas independently evolved the knuckle gait.)

Now, I'm not quite sure if this sort of peculiar circumstances would mean anything for wikipedia standards, I'm not just asking to remove because I don't like all that fringeness... if there's nothing "official" against that, ok, I'll just shut up, it remains there... but that's a shame... --Extremophile 06:51, 29 September 2007 (UTC)

I removed the sciencenews external link, which at the least is sensationalist and fairly unhelpful. As to the Schwartz reference within the text, I don't know, but it doesn't seem unreasonable to me as it is used. Of course, the primate phylogeny issue is something that has been extremely contentious since molecular evolution first came on the scene and people started claiming that chimps were our closest relatives. In the article, Schwartz is described as being on the same side as Ayala on this issue, which certainly doesn't lend any support to the idea that challenging the molecular clock challenges Darwinian evolution generally (at least in this context).--ragesoss 13:23, 29 September 2007 (UTC)