© 2006 Society of Systematic Biologists
Multiple Origins of the Juan Fernández Kelpfish Fauna and Evidence for Frequent and Unidirectional Dispersal of Cirrhitoid Fishes Across the South Pacific
1 School of Life and Environmental Sciences, Deakin University, PO Box 423 Warrnambool, Victoria, 3280, Australia
2 Museo Nacional de Historia Natural Casilla 787, Santiago, Chile
3 Escuela Recursos Naturales, Universidad del Mar Amunátegui 1838, Viña del Mar, Chile
Edited by Adrian Patterson: Associate Editor
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Abstract |
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Phylogenetic relationships were reconstructed among chironemid fishes based on morphological and molecular (lrRNA, NADH4, S7 ribosomal protein) characters. Two sympatric species from Juan Fernández in the southeast Pacific are not sister taxa, but rather exhibit independent relationships to Australian/New Zealand chironemids. The most plausible explanation for these relationships and contemporary distributions is an Australian/New Zealand origin of the family, followed by two trans-Pacific dispersal and colonization events, facilitated by larval entrapment within the West Wind Drift. This study demonstrates that the diversity of taxa on an island can reflect multiple colonizations, rather than in situ diversification, even in the case of very small, isolated, and geologically recent islands. When taken in conjunction with studies of related taxa, our results indicate that transoceanic dispersal of temperate cirrhitoid fishes in the South Pacific has been frequent and unidirectional. Molecular estimates of divergence time between southeast Pacific chironemids and their western relatives predate the emergence of Juan Fernández, consistent with hypotheses that much of the marine nearshore faunas of young southeast Pacific islands may be the product of successive transfer from older, now submerged islands.
Keywords: Approximately unbiased test; biogeography; combinability; dispersal; island; seamount; Southern Hemisphere; West Wind Drift
Received November 21, 2004; Revised February 14, 2005; Accepted March 6, 2006
4 Current Address: Department of Zoology, University of Otago, 340 Great King Street, Dunedin, New Zealand E-mail: Chris.Burridge{at}stonebow.otago.ac.nz (C.P.B.)