"Most mutations are negative than those that are beneficial. The best you get is a ratio of 10,000 to 1. In other words, mutations will tend to drive species to extinction before it has an opportunity to naturally evolve.
Unless it has a truly enormous population size, more than a quadrillion, a body size less than one centimeter, and a generation time briefer than 3 months.
Now you can go to the field biologists. Where do you see speciation going on in the real world? They only see it for those species that match the mathematical limits. Those that don't, all they see is extinction." - Hugh Ross