Polyploidy isn't gradual. That toad with his eyes on the roof of his mouth that I mentioned in the last post did not get there gradually. His parents did not have eyes on their noses. Still, many mysteries remain. I do not deny the operation of natural selection.
Development also works on a sliding scale.
NS starts low and ends high. When you get right down to it, we are no more complex biologically from many invertebrates. Our cells perform the same function with similar structures, they have eyes, mouths, digestive systems, blood, etc. There is none of theis high and low business. None of this higher and lower animals as far as I can see.