Friday, August 31, 2012

[Ornithology • 2012] Madagascar's Vangas beat Darwin’s finches in diversity • Extreme endemic radiation of the Malagasy Vangas (Passeriformes: Vangidae)

The Madagascan vangas include 22 species which differ considerably in terms of morphology and resulting foraging habits.. 
photo: Jon Fjeldså

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.

Keywords: core corvoidea, island endemism, lineage diversification, passeriformes, phylogenetics

The vanga family's members, revealing their extreme morphological diversity (Proceedings of the National Academy of Sciences)
Helmet vangas measure up to 30 centimeters. The bird has a huge blue bill which it uses to catch lizards, frogs and geckos. 
photo: Nick Athanas 

 Yamagishi, S.; Honda, M.; Eguchi, K. & Thorstrom, R. 2001. Extreme endemic radiation of the Malagasy Vangas (Aves: Passeriformes). J. Mol. Evol. 53(1): 39-46.

Jønsson, K.A; Fabre, P.-H.; Fritz, S.A. et al. 2012. Ecological and evolutionary determinants for the adaptive radiation of the Madagascan vangas. PNAS Early Edition. doi: 10.1073/pnas.1115835109

Evolution: Vangas beat Darwin’s finches in diversity

Evolution: Vangas beat Darwin’s finches in diversity: 
Madagascar’s vanga birds, new study