I agree with you that it is hard to imagine certain structures just appearing on the scene suddenly by slow accumulations of genetic traits. I saw a program once about the Pterosaurs and how they had radically different forms than anything before and these structures were crucial for flight. In fact it seemed to the scientists studying it that if any one of these were missing it could not have flown. What would the transitional forms that could not fly do with a 10 ft. long finger. That’s what formed the wing. I don’t agree though that all mutations are harmful though. Some, like a different pigment that helps an animal blend in better and avoid predators would be helpful.
different pigment isn’t a mutation, they had that information in there genes as an option, all along. the ones with poor coloring get eaten off, so no kidding the ones that prosper are the ones that belnd in better.
different colors are variations in an existing gene, not new info or mutations. for the mths you’re talking about, when the trees were dark, the lighter moths got’picked’off and most of the dark ones were the majority, when coal got clener and the trees weren’t so sooty anymore, they found the dark ones stuck out and birds ate them and the nubmers of the lighter moths increased.