Reply #32: random processes are the main part of evolution

[tocqueville]

Evolution is not ONLY selection. To evolve means to change. Natural selection is the only process that cannot happen at random. But the 3 other processes are going to influence the selection and happen at random. That's why you cannot find a DESIGN in the result. If there was only selection you'll have an infinite variety of clones, living side by side. But dinosaurs wouldn't have evolved into birds.

Evolution :

1) Natural selection : not random because based on differential fitness
2) Genetic drift : random
3) Gene flow : can be at random (transfer of genes from population to population)
3) Mutation : random

I agree that the correct term is that evolution happens MOSTLY at random

Genetic drift is a contributing factor in biological evolution, in which traits which do not affect reproductive fitness change in a population over time. Whereas natural selection causes traits to become more prevalent when they contribute to fitness, or eliminates those which harm it, genetic drift is a somewhat random process which affects traits that are more neutral.

Genetic drift is a statistically stochastic process that arises from the role of random sampling in the production of offspring. The genes of each new generation are not a simple copy of the genes of the successful members of the previous one, but rather a sampling, which includes some statistical error. Drift is the cumulative effect over time of this sampling error on the allele frequencies in the population.