A new study has revealed that the long-distance migration of the new world birds evolved out of North America after the researchers analyzed more than 750 species of their ancestral ranges.
A team of scientists from the University of Chicago developed a new method to disclose the ancestral ranges of New World birds, and discovered that bird migration in the Americas evolved in species that resided in North America.
Seasonal migration - which occurs when species breed in one geographical area and winter in another - is commonly hypothesized to have evolved as ancestral species native to the tropics began to shift their breeding ranges northward.
The team mapped these ranges to a phylogenetic tree i.e. a diagram which showed the evolutionary relationships of each passerine species and their common ancestors to reconstruct where ancestral passerines lived.
"We find that a North American species is ancestral to migratory birds in the New World," said Winger, who is the corresponding author on the study. "It's been assumed that because species density is so high in the tropics, that migratory birds must come out of the tropics. But our study suggests the opposite happened more frequently in this group. The evolution of migration is a complex system. Our study highlights the importance of using phylogenies to study this phenomenon."
The study is published in the Proceedings of the National Academy of Sciences.
