Aren’t these authors trying to show how *fast* an eye can evolve?
No. Figuring out what they
aretrying to show is left as an exercise for the student.
Do genetic deaths impact the rate at which new beneficial substitutions can fixate in populations?
Under some circumstances, yes. Care to name those circumstances?
[one per 300 generations] is a best-case number for the beneficial substitution rate.
Nope. I notice you ignored my point about assumptions. Care to name the assumptions which are requred for 1 per 300 to be the best-case number?
You are missing the point. What if a certain, specific step S had to occur before S+1?
Then step S+1 will not occur until after step S.
The model assumes the steps can happen in any order, yet another huge stretch but not as severe a leap as their total avoidance of the genetic death/substitution cost problem.
You are totally failing to understand. They
do not assume that the steps can happen in any order. That is your myth.