[Taxacom] Origin of New Caledonian biogeography

John Grehan jgrehan at sciencebuff.org
Mon Nov 17 13:07:47 CST 2008

This paper should be relevant to anyone interested in the integration of biogeography and earth history. A pdf can be accessed at 




Biological disjunction along the West Caledonian fault,

New Caledonia: a synthesis of molecular phylogenetics

and panbiogeography



This paper documents a newly discovered pattern of biological disjunction between NW and SE New Caledonia.

The disjunction occurs in 87 (mapped) taxa, including plants, moths and lizards, and correlates spatially with the

West Caledonian fault. This fault is controversial; some geologists interpret it as a major structure, others deny

that it exists. It may have undergone 150–200 km of lateral movement and it is suggested that this has caused the

biological disjunction by pulling populations apart. The disjunction matches similar dextral disjunctions of taxa

along transform faults in New Zealand, New Guinea, California and Indonesia. Major biogeographic patterns –

whether centres of diversity, boundaries of allopatric taxa or disjunctions – all include taxa with many different

degrees of differentiation. Studies using a clock model of evolution will therefore interpret a biogeographic pattern

as the result of many disparate events. However, this line of reasoning reaches the untenable conclusion that

biogeographic patterns, including normal allopatry, are always caused by chance dispersal, never by vicariance. A

more productive approach, avoiding the pitfalls of a fossil-based molecular clock, involves a close examination of

molecular clades, comparative biogeography and tectonics. The New Caledonia example documented here shows

that this can lead to novel, testable predictions.


Dr. John R. Grehan

Director of Science

Buffalo Museum of Science1020 Humboldt Parkway

Buffalo, NY 14211-1193

email: jgrehan at sciencebuff.org

Phone: (716) 896-5200 ext 372




Ghost moth research


Human evolution and the great apes




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