The “Random Genetic Drift” Fallacy — a review

I often see suggestions that random genetic drift drives speciation.  I’m a bit skeptical of that idea.  In any case, a discussion developed elsewhere, and Will Provine’s recent book on the topic was suggested as reading.  I found the book interesting, though perhaps not decisive on the issues.  So I am still at the same point of skepticism as where I started.  But I at least have a better grasp of some of the issues.

I should add that I am not a biologist, though I have taken an interest in evolutionary biology.

What is random drift?

Let’s start by looking at the main issue.  The proponents of random drift seem to be suggesting that

• there are near neutral mutations (neither benefiicial nor deleterious)
• by random chance, some of those neutral mutations take over the population (the new genes become fixed).

That is the sort of drift that Provine is discussing.