Again, insertions, allopolyploidy, and mutations.
Sure it’s testable: do we see examples of this in short-lifespan organisms? Yes. Do we see examples of this as fossils? Yes.
Neither are hurricanes, and yet we can describe them pretty well.
Until we add a long enough period of time for those changes to produce separate species (by “long enough”, I mean somewhere between decades and tens of millions of years, depending on conditions).
Allopolyploidy can create a new species in a single generation, by making the descendant population reproductively incompatible with the parent population.
It’s really a rather inconvenient reason, as it makes testing of mechanisms much more difficult than one might like.
They are in the fossil record, like going from early Cambrian “monoplacophorans” to neogastropods or Myllokunmingiidae to modern mammals.
But they are intermediate in age and morphology between lancelet-like proto-chordates and more standard fish.
They are intermediate in age and morphology between proto-lobopodians and more modern groups of arthropods.
No, they don’t. They show a clear directional trend over time from normal rostroconchs to modern scaphopods.
Not under any standard definition of a species–Busycon maximum and Busycon carica have no morphological overlap, Ensis directus and Ensis leei have no morphological overlap, Pelycidion matthewi and Pelycision megalomastoma have no morphological overlap, and the list can go on.
That’s definitely wrong given the population sizes that I’m dealing with.
They are sufficiently close in morphology to the older fossil species and the living species to make that untenable.
No, it is based purely on observation of their stratigraphic position and morphology.
They are intermediate in age and morphology between many stem-synapsids and standard mammals.
They are intermediate in morphology between earlier sarcopterygian fish and more modern amphibians.
I am talking about exactly what molecular clock dating does.
They are the same thing.
I see them because they are there. They are intermediate in stratigraphic position and morphology between other taxa. If they were not intermediate in morphology and stratigraphic position, then I would not conclude that they are intermediates.
Again, if they are variations within a species, then that requires redefining “species”, pathology is incompatible with hundreds of specimens, and completely different species is incompatible with the levels of difference between them.
What and where are they? Until and unless demonstrable and precise barriers can be found, this is simply an unevidenced assertion.
There are roughly equal numbers of slightly beneficial and slightly deleterious mutations. Extremely deleterious mutations are much more common than extremely beneficial mutations, but the former don’t accumulate, so the occasional highly beneficial mutations will be significant.
This is an unquantified assertion, not an empirical mathematical reality. If this used actual, measured rates of different types of mutations, then it would be interesting.
I have considered that possibility, and found it unconvincing.
You’re asking for something that shouldn’t exist as evidence for something it would not be evidence for.
No, it is not, unless I and every one of my colleagues in molluscan systematics doesn’t know what we are doing.