Warmer colours denote a higher rate of diversification.
"The Bees have the highest rate of diversification -- well above the black line denoting the overall diversification rate for hummingbirds", writes Professor McGuire in email.
By looking at the rate of diversification, geneticists can make a guess about how long ago all AIDS strains were the same.
However, the rate of diversification in the Hylopezus/Myrmothera clade appeared to have remained constant through time, with no major shifts over the 20 million years.
These findings demonstrate that the rate of diversification has decreased for marine fish over the Cenozoic but is in sharp expansion for freshwater fish.
This is quite recent for this modern avian family, particularly in view of the large number of species that are alive today, revealing these birds experienced a rapid rate of diversification after they reached South America.
Professor McGuire added that although the Bees and certain other groups are still diversifying rapidly and will do so for a long time to come, the rate of diversification has slowed for all hummingbird clades -- particularly for the Brilliants and Coquettes, which diversified primarily in the Andes.
Instead of expecting an explosion of dinosaur diversity corresponding to the rise of angiosperms, he says, it's possible the plants prevented a decline in the rate of diversification.
A new avian family tree, represented here as a circle, reveals this increasing rate of diversification of feathered creatures during the past 50 million years.
Yet some studies have demonstrated that dispersal into new areas can lead to an increase in the rate of diversification (e.g., Moore and Donoghue 2007), which suggests that there is a relationship between the rate of cladogenesis and biogeographic evolution.
Over the following 70 or 80 million years, the rate of diversification accelerated by an order of magnitude and the diversity of life began to resemble that of today, although they did not resemble the species of today.
