On the other hand, if this sim was saved prior to 2.42.4 and had a ton of mutations and you used the buddy drop I posted to re-load it and strip the mutation details, then one possible side effect of that action is that the per-bot mutation rates can be screwed up. They come after the mutation details in the sim file format and there isn't much I could do about that without writing more code then I wanted to.
Unfortnatuly, I don't know of a good way to fix or even check this. The mutation rates that one specifies on the Species tab are actually stored along with each individual, duplicated with each bot, not stored globally for the species. I presume this is so that the mutation rates for specific individuals are themselves heritable and thus subject to evolvution and change.
This won't happen with new sims which begin with 2.42.4 or old sims which newer blew the old mutations details limit, but for sims which did....
Any new bots you add to the sim will respect the mutation rates you specify. You could cut the DNA from some of your bots, create a few new species and re-add them... If you really wanted to save this sim, I suppose you could modify the sim save routine in the code to save the sim with the mutation rates you wanted. Then when you re-load it, all would be well...