Nexus file for: Molecular diversification of hummingbirds

The tempo of species diversification in large clades can reveal
fundamental evolutionary mechanisms that operate on large temporal and
spatial scales. Hummingbirds have radiated into a diverse assemblage of
specialized nectarivores comprising 338 species, but their evolutionary
history has not, until now, been comprehensively explored. We studied
hummingbird diversification by estimating a time-calibrated phylogeny for
284 hummingbird species, demonstrating that hummingbirds invaded South
America by ~22 million years ago, and subsequently diversified into nine
principal clades. Using ancestral state reconstruction and diversification
analyses, we (1) estimate the age of the crown-group hummingbird
assemblage, (2) investigate the timing and patterns of lineage
accumulation for hummingbirds overall and regionally, and (3) evaluate the
role of Andean uplift in hummingbird speciation. Detailed analyses reveal
disparate clade-specific processes that allowed for ongoing species
diversification. One factor was significant variation among clades in
diversification rates. For example, the nine principal clades of
hummingbirds exhibit ~15-fold variation in net diversification rates, with
evidence for accelerated speciation of a clade that includes the Bee,
Emerald, and Mountain Gem groups of hummingbirds. A second factor was
colonization of key geographic regions, which opened up new ecological
niches. For example, some clades diversified in the context of the uplift
of the Andes Mountains, whereas others were affected by the formation of
the Panamanian land bridge. Finally, although species accumulation is
slowing in all groups of hummingbirds, several major clades maintain rapid
rates of diversification on par with classical examples of rapid adaptive
radiation.