Evolution 101- part 9: Hope, Change, and Lethal Mutations

Remember, normal text is copied from Evolution 101 by the Understanding Evolution team! (now serving the tri-state area!) http://evolution.berkeley.edu/

BOLD font is me, Rent A Friend 2000, being Bold.

Mechanisms of change

Each of these four processes is a basic mechanism of evolutionary change.

Mutation A mutation could cause parents with genes for bright green coloration to have offspring with a gene for brown coloration. That would make genes for brown coloration more frequent in the population than they were before the mutation.Or a pre-existing recessive gene. A change in the frequency of a trait does NOT equate to a change in the genes of the individuals. Besides, in the example given, the beetles already had genes for brown. This has no bearing on the story above unless it is meant to explain why brown beetles exist in the first place, which, in the paragraph above, they do not attempt to do.

Migration Some individuals from a population of brown beetles might have joined a population of green beetles. That would make genes for brown coloration more frequent in the green beetle population than they were before the brown beetles migrated into it.Do I need to say how this doesn’t represent new genetic information? Let’s all take a second and remember that Evolution is supposed to explain the process by which bacteria became wolves and cabbages.

Genetic drift Imagine that in one generation, two brown beetles happened to have four offspring survive to reproduce. Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation — but just by chance. These chance changes from generation to generation are known as genetic drift.Once again, no new genetic information has been produced, so this isn’t evolution. This is more like the effects of bad weather on your car. Maybe it explains some rust spots, but it tells you nothing about your car, or next year’s model.

Natural selection Imagine that green beetles are easier for birds to spot (and hence, eat). Brown beetles are a little more likely to survive to produce offspring. They pass their genes for brown coloration on to their offspring. So in the next generation, brown beetles are more common than in the previous generation.

According to the title of Darwin’s book, Natural Selection is supposedly the means by which species originate. At least, that’s my interpretation of “Origin of the Species by Means of Natural Selection,” but as you know there are so many interpretations, it’s impossible to know what Darwin really meant when he wrote that all those years ago. But look at Natural Selection- it removes a part of the population. If this happened often enough, and wide enough, it is hypothetically possible that it could cause the loss of an allele permanently- meaning the gene for green would not exist in any surviving beetles.

Once again, this is not evolution. You cannot turn bacteria into wolves and cabbage by losing alleles. Natural selection as a mechanism of evolution is like spending your way out of debt (politicians, please consult a business person to explain this to you).

Furthermore, this idea was nor Darwins, but was taken from the writings of a Biblical Creationist, Edward Blyth who wrote about Natural selection in 1835as being a stabilizing element to protect the created kinds from harmful changes, which is exactly what we observe. Darwin took Blyth’s idea of a process by which corruption is removed for the benefit of the species, and imagined it as the creative process which created the species in the first place, which of course is non-sense. Natural selection cannot create anything. It is merely quality control.

To bring the point home, checkout this quote: “It must not be forgotten that mutation is the ultimate source of all genetic variation found in natural population and the only new material available for natural selection to work upon.” *E. Mayr, Populations, Species and Evolution (1970), p. 103

All of these mechanisms can cause changes in the frequencies of genes in populations,

This part is true.

and so all of them are mechanisms of evolutionary change.

This part is not true. Even on their weak sauce definition of evolution.

However, natural selection and genetic drift cannot operate unless there is genetic variation — that is, unless some individuals are genetically different from others. If the population of beetles were 100% green, selection and drift would not have any effect because their genetic make-up could not change.

This part is true. Are you enjoying the vast fluctuation between true and ridiculous? It’s a lot like reading the ingredients on Cheetoes or Twinkies. Occasionally you see something real among all of the alien substances.

Join me next week for part 10.

Rentafriend2000@hotmail.com

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