Taking the facts and arguments presented together, it appears to be clear that no macroevolution is happening in “Darwin’s finches.”
The authors offer a selectionist explanation, which is nevertheless uncertain. Note the repeated use of the subjunctive.
This is by no means an all-or-nothing selection (as the impression is sometimes given). Rather, the alleles are retained.
Scientific data are followed by the myth: “Finch beak morphology observed on the Galápagos Islands was used by Darwin to formulate his theory of evolution.”
In a series of posts starting today, I offer some notes on the question of whether macroevolution is happening on the Galápagos Islands.