22m years later, hummingbird evolution still soaring

A new exhaustive family tree of hummingbirds -- published today in the journal Current Biology -- reveals the remarkable 22-million year evolutionary journey from a single common ancestor to today's assemblage of 338 different species. It's the story of a tiny bird which begins in Europe 22 million years ago. After making its way to Asia and North America, and the delicate creature suddenly and rapidly flourishes in South America -- its family radiating out into 140 new species amongst the varied terrain and thin air of modern-day Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina. Though the forests of the Andes Mountains account for only 7 percent of the world's land mass, the habitat is home to some 40 percent of all hummingbird species. "Our study provides a much clearer picture regarding how and when hummingbirds came to be distributed where they are today," explained lead author Jimmy McGuire, professor of integrative biology at University of California, Berkeley. From the Andes, the newly rich array of hummingbirds invaded the Caribbean and North America and continued to evolve. Some species, having developed new characteristics, slowly made their way back south and recolonized the Andes, competing with their old lineages. The new family tree reveals these details and more -- plotting intricate and complicated evolutionary paths of all 338 current species, from the ancient to the modern. Though variation rates are declining, the authors of this latest study say hummingbirds aren't through evolving. They say the number of species could double in the next several million years. "We are not close to being at the maximum number of hummingbird species," McGuire said. "If humans weren't around, they would just continue on their merry way, evolving new species over time."