"Darwin's Rheas"


Darwin's Rhea
Public DomainDarwin's Rhea - Credit: John Gould

The Rhea is a rare, flightless bird indigenous to Patagonia. Darwin was told about it by the Indians on his second voyage aboard HMS Beagle.

He later discovered there are different sub-species living in separate parts of Patagonia, which led him to develop his theory that species are not fixed but can evolve and divide.