The shifting songs of Darwin’s finches have given new insight into processes that shape the course of evolution, preventing newly forked branches on life’s tree from growing back together.
Even though it’s biologically possible for Geospiza fortis and Geospiza scandens — the original residents of the Galapagos island of Daphne Major — to interbreed with newly arrived Geospiza magnirostris, the species have stayed separate.
The birds learned to sing new tunes, setting off a behavioral cascade that swept the island in just a few decades: Evolution in action, audible to the naked ear.
The findings, published October 31 in the Proceedings of the National Academy of Science, “throw light on what happens at a crucial stage in speciation,” wrote Princeton biologists Rosemary and Peter Grant.
Since the late 1970s, the Grants have worked on Daphne Major, studying descendants of some of the same finches that inspired Charles Darwin’s evolutionary theories.