As Darwin outlined these main lines of objection, they included first the apparent absence of numerous slight gradations between species, both in the present and in the fossil record, of the kind that would seem to be predictable from the gradualist workings of the theory chps.
Katherine Tillman, and the anonymous reviewers for the Stanford Encyclopedia of Philosophy.
The latter were now the form of variation to be given primary evolutionary significance, and presumably this was more likely to be transmitted to the offspring, although details are left unclear.
You could have a big dog or a small dog, a dog with long or short hair.