Résumé
Adaptive radiation is the rapid diversification of a single lineage into
many species that inhabit a variety of environments or use a variety of
resources and differ in traits required to exploit these. Why some
lineages undergo adaptive radiation is not well-understood, but filling
unoccupied ecological space appears to be a common feature. We construct a
complete, dated, species-level phylogeny of the endemic Vangidae of
Madagascar. This passerine bird radiation represents a classic, but poorly
known, avian adaptive radiation. Our results reveal an initial rapid
increase in evolutionary lineages and diversification in morphospace after
colonizing Madagascar in the late Oligocene some 25 Mya. A subsequent key
innovation involving unique bill morphology was associated with a second
increase in diversification rates about 10 Mya. The volume of morphospace
occupied by contemporary Madagascan vangas is in many aspects as large
(shape variation)—or even larger (size variation)—as that of other
better-known avian adaptive radiations, including the much younger
Galapagos Darwin's finches and Hawaiian honeycreepers. Morphological
space bears a close relationship to diet, substrate use, and foraging
movements, and thus our results demonstrate the great extent of the
evolutionary diversification of the Madagascan vangas.