Hummingbirds took just 22 million years to diversify from a single common ancestor into 338 tiny, colorful species. And they have not finished yet.
Evolutionary biologist Jim McGuire of the University of California, Berkeley, and his collaborators have found that although some hummingbird groups have saturated the available space in their environments, others are still developing into new species at an extraordinary rate. By comparing their rates of speciation and extinction, McGuire’s team calculated that the number of hummingbird species could double before reaching an equilibrium in the next several million years. The results are published in Current Biology.
“This is unique evidence of one of the most spectacular known examples of an incomplete adaptive radiation,” says Juan Francisco Ornelas, an evolutionary biologist at the Institute of Ecology in Xalapa, Mexico. (‘Adaptive radiation’ is biologists’ term for a rapid differentiation into distinct species.)