How do beneficial mutations appear? In bacteria it is a problem as this study shows. What about animals that are on land? They are not bacteria. It is difficult to have horizonal transfer, although it can happen through ticks as I recently showed. The study produces more objections to gradual Darwinism than solves the issue. Punctuated equilibrium is not answered through bacterial study, but those studies may evenually help us figure it out.-http://medicalxpress.com/news/2013-03-beneficial-mutations-specific-circumstances.html