Evolution vs. Creationism

Mr ProgFreak wrote: Dean wrote: There is no conflict in the various methods, all are capable of driving evolution dependant on the relative stability of environment, population sizes, etc. and whichever one is dominant is probably determined by the stability of all those factors. For example in a stable environment of small populations genetic drift may well overshadow any advances governed by natural selection.   I don't see where either of us has said that there is no natural selection, or even implied that. I don't see either where I said there's no other force beside natural selection at work. But how could for example genetic drift be a driving force in evolution? "Genetic drift is an important evolutionary process which leads to changes in allele frequencies over time. It may cause gene variants to disappear completely, and thereby reduce genetic variability. In contrast to natural selection, which makes gene variants more common or less common depending on their reproductive success,[2] the changes due to genetic drift are not driven by environmental or adaptive pressures, and may be beneficial, neutral, or detrimental to reproductive success." As I see it - through layman eyes - genetic drift could not be a *driving* force like natural selection. It seems more like an element of chance to me. Of course elements of chance can also have great effects, but not in a guiding or driving manner.

^ the effect of the natural environment on the probability of survival for genetic variations of lifeforms. But regardless of whether I jump through your hoop or not, it's not my job to define a term that has long been defined.

It gets down to dicing words, but...

^ can you describe the effect of genetic drift or punctuated equilibrium by a simple example? Especially how they play a greater role than natural selection.

http://forum.richarddawkins.net/viewtopic.php?f=14&t=72053

I feel vindicated.

^ That's a relief, since it's not such a big help in explaining how evolution could have achieved complex forms of life like humans - is it? It can explain how some branches of the tree of life became extinct or others were favored, but it doesn't explain how those that were favored continued their evolution. To explain that, you need natural selection.

EDIT: Actually such a cataclysmic event could even be seen as an (extreme) case of natural selection - if the term was used in a slightly broader sense.


Edited by Mr ProgFreak - December 06 2009 at 17:34

^ no problem at all ... what bothers me more is that this is totally off topic and unnecessary to understand the principle of evolution by natural selection. I'm really annoyed by how Negoba is systematically trying to complicate the matter. "Willful Obscurity", I think that's the term Dan Dennett used in a similar situation.

Mr ProgFreak wrote: ^ no problem at all ... what bothers me more is that this is totally off topic and unnecessary to understand the principle of evolution by natural selection. I'm really annoyed by how Negoba is systematically trying to complicate the matter. "Willful Obscurity", I think that's the term Dan Dennett used in a similar situation.

I have to disagree with you here. Genetic drift is a powerful force in evolution. Unfortunately, Dawkins (and Coyne, to some extent, I believe) fall closer to "adaptationism" - the idea that natural selection can explain nearly everything of an organism's phenotype.

As far as I can tell, we currently do not know exactly how powerful drift is. We know it's incredibly important at the molecular level (neutral theory), but how this interacts with the phenotype is still a bit unclear. One example of the effects of drift is the fact that Native Americans all have an O blood type. (I haven't personally investigated this but it's an example I see often.)

One author, Michael Lynch, believes that most of the genomic architecture of eukrayotes can be explained by non-adaptive processes (paritcularly, drift). He believes that introns/exons, transposons, repetitive sequences, etc. are due to processes that are not natural selection.

This isn't a needless topic.

(Right now, I'm planning on writing a paper and presenting a seminar (undergrad senior seminar) about this very topic: What are the relative roles of natural selection and genetic drift in explaining the history of life? Or something along those lines at least. I'm still early in the research part though, so I can't give you a bunch of examples as to how important drift is. )

I will continue to systematically try to complicate the matter.

Dean wrote: Mr ProgFreak wrote: ^ no problem at all ... what bothers me more is that this is totally off topic and unnecessary to understand the principle of evolution by natural selection. I'm really annoyed by how Negoba is systematically trying to complicate the matter. "Willful Obscurity", I think that's the term Dan Dennett used in a similar situation. Well, one of the reasons is to equip all evolutionist with an arsenal of knowledge to combat the criticisms from the creationist/ID lobby, this includes discussing all evolutionary mechanisms even if only among ourselves, so when they come up with some example where natural selection appears to fail such as those mutations that do survive but are not necessary for survival (like hair colour), we can point to one of the other mechanisms that does explain it.

Edited by AmbianceMan - December 06 2009 at 22:59