"beneficial mutations"

[mr24shoe]

My favorite example (shows mutations are only beneficial/detrimental in a given environment; until then, they're neutral...shows humans still evolving)

from http :// talkorigins.org /faqs/mutations.html

Sickle cell resistance to malaria :
The sickle cell allele causes the normally round blood cell to have a sickle shape. The effect of this allele depends on whether a person has one or two copies of the allele. It is generally fatal if a person has two copies. If they have one they have sickle shaped blood cells.
In general this is an undesirable mutation because the sickle cells are less efficient than normal cells. In areas where malaria is prevalent it turns out to be favorable because people with sickle shaped blood cells are less likely to get malaria from mosquitoes.
This is an example where a mutation decreases the normal efficiency of the body (its fitness in one sense) but none-the-less provides a relative advantage.

 

[mark kennedy]

Fitness effects of advantageous mutations in evolving Escherichia coli populations

This one was kind of interesting, they start out saying what we both allready knew. Beneficial effects from mutations are so rare they are virtually impossible to study. In a thousand generations they identified 66 adaptive events.

 

[Apos]

Can you make up your mind? Are they impossible, or just rare? If just rare, I'd say that 66 major adaptive events in thousands of
generations of a relatively miniscule population is actually pretty speedy and common, on the evolutionary scale. Remember, in reality, outside of creationist fatansy camp, the real question in biology is not why or how evolution could move so fast, but rather, why has it moved so comparatively slow given how quickly variations build up.

 

[mark kennedy]

Can you make up your mind? Are they impossible, or just rare? If just rare, I'd say that 66 major adaptive events in thousands of
generations of a relatively miniscule population is actually pretty speedy and common, on the evolutionary scale. Remember, in reality, outside of creationist fatansy camp, the real question in biology is not why or how evolution could move so fast, but rather, why has it moved so comparatively slow given how quickly variations build up.

I have made up my mind and I never said it was impossible for a mutation to have a slight selective advantage.

"Among the mutations that affect a typical gene, different kinds produce different impacts. A very few are at least momentarily adaptive on an evolutionary scale. Many are deleterious. Some are neutral, that is, they produce no effect strong enough to permit selection for or against; a mutation that is deleterious or advantageous in a large population may be neutral in a small population, where random drift outweighs selection coefficients...

With 6.4 x 109 base pairs in the diploid genome, a mutation rate of 10-8 means that a zygote has 64 new mutations. It is hard to image that so many new deleterious mutations each generation is compatible with life, even with an efficient mechanism for mutation removal. Thus, the great majority of mutations in the noncoding DNA must be neutral."

http://www.genetics.org/cgi/content...RSTINDEX=0&minscore=5000&journalcode=genetics

Mutations for the most part do absolutly nothing.

 

[Split Rock]

Mutations for the most part do absolutly nothing.

Yes Mark, but the key aspect here is for the most part. The example I gave earlier concerning resistance to glyphosate shows that a single mutation can bestow a significant survival benefit. Note that this occurred before the population was overwelmed by the build-up of deleterious mutations you claim go hand-in-hand with such an occurrance.