Three Different North American Siskin/Goldfinch Evolutionary Radia-tions (Genus Carduelis): Pine Siskin Green Morphs and European Siskins in America

Abstract

Three separate and parallel North American Carduelis evolutionary radiations have been identified. North American siskin radiation (starting about 2.7 million years ago) comprises siskin, Antillean siskin, black-capped siskin, pine siskin and pine siskin perplexus. C. spinus could have passed to America through the Beringia or Greenland coast and, during Pliocene Epoch, reached the Antilles and evolved into Antillean siskin (C. dominicensis), endemic to Hispaniola Island. It is ancestor of pine siskin. Pine Siskin, also a sister taxon of C. spinus, thrives in North America from Alaska to Guatemala since about 0.2 MYA. It lives below the Mexican Isthmus in the highlands from northern Chiapas (Mexico) to western Guatemala. Black-capped siskin (C. atri- ceps) is a sister species of C. spinus, with which it shares habitat and territory. C. pinus green-backed morphs may have been mis- taken by C. atriceps which is a grey-backed finch. Mesoamerican goldfinch radiation (starting about 5 million years ago) includes C. tristis (American goldfinch), C. psaltria (lesser goldfinch) and C. lawrencei (Lawrence's goldfinch). They all thrive in west- ern United States and Mexico, down to northern South America. C. psaltria is a North American bird that colonized South American habitats to North Peru and evolved into darker head and back while going southwards. South American siskin radiation started about 3.5 million years ago; parental C. notata thrives in Mexican mountains and successfully colonized South America, giv- ing rise to this radiation. South American Carduelis radiation occurred only when mesothermal plants from the Rocky Mountains invaded the Andean spine after emergence of the Panama Isthmus.