Chameleon radiation by oceanic dispersal.
Historical biogeography is dominated by vicariance methods that search for a congruent pattern of fragmentation of ancestral distributions produced by shared Earth history. A focus of vicariant studies has been austral area relationships and the break-up of the supercontinent Gondwana. Chameleons are one of the few extant terrestrial vertebrates thought to have biogeographic patterns that are congruent with the Gondwanan break-up of Madagascar and Africa. Here we show, using molecular and morphological evidence for 52 chameleon taxa, support for a phylogeny and area cladogram that does not fit a simple vicariant history. Oceanic dispersal--not Gondwanan break-up--facilitated species radiation, and the most parsimonious biogeographic hypothesis supports a Madagascan origin for chameleons, with multiple 'out-of-Madagascar' dispersal events to Africa, the Seychelles, the Comoros archipelago, and possibly Reunion Island. Although dispersal is evident in other Indian Ocean terrestrial animal groups, our study finds substantial out-of-Madagascar species radiation, and further highlights the importance of oceanic dispersal as a potential precursor for speciation.
Raxworthy
C J
CJ
American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024-5192, USA. rax@amnh.edu
Forstner
M R J
MR
Nussbaum
R A
RA
D000349:Africa; D000818:Animals; D005075:Biological Evolution; D004641:Emigration and Immigration; D004777:Environment; D019143:Evolution, Molecular; D005843:Geography; D007194:India; D019156:Indian Ocean; D008116:Lizards / Q000145:classification / Q000235:genetics / Q000502:physiology*; D008270:Madagascar; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny