Endemism and dispersal: comparative phylogeography of three surgeonfishes across the Hawaiian Archipelago
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ORIGINAL PAPER
Endemism and dispersal: comparative phylogeography of three surgeonWshes across the Hawaiian Archipelago JeV A. Eble · Robert J. Toonen · Brian W. Bowen
Received: 18 June 2008 / Accepted: 16 December 2008 / Published online: 6 January 2009 © Springer-Verlag 2009
Abstract To evaluate the hypothesis that a general correlation exists between species range size and dispersal ability, we surveyed mitochondrial cytochrome b sequence variation in three surgeonWsh species with vastly diVerent ranges: Ctenochaetus strigosus, Hawaiian endemic, N = 531; Zebrasoma Xavescens, North PaciWc, N = 560; Acanthurus nigrofuscus, Indo-PaciWc, N = 305. Collections were made throughout the 2,500 km expanse of the Hawaiian Archipelago and adjacent Johnston Atoll. Analyses of molecular variance demonstrate that all three species are capable of maintaining population connectivity on a scale of thousands of km (all species global ST = NS). However, rank order comparison of pairwise ST results and Exact test P-values revealed modest but signiWcantly diVerent patterns of gene Xow among the three species surveyed, with the degree of genetic structure increasing as range size decreases (P = 0.001). These results are consistent with mtDNA surveys of four additional Hawaiian reef fauna in which a wide-spread Indo-PaciWc species exhibited genetic homogeneity across the archipelago, while three endemics had signiWcant population subdivision over the same range. Taken together, these seven cases invoke the hypothesis that Hawaii’s endemic reef Wshes evolved from species with reduced dispersal ability that, after initial colonization, could not maintain contact with parent populations.
Communicated by M.I. Taylor. Electronic supplementary material The online version of this article (doi:10.1007/s00227-008-1119-4) contains supplementary material, which is available to authorized users. J. A. Eble (&) · R. J. Toonen · B. W. Bowen Hawaii Institute of Marine Biology, P.O. 1346, Kaneohe, HI 96744, USA e-mail: [email protected]
Introduction The life histories of most marine species are characterized by an early pelagic larval phase followed by a relatively sedentary juvenile and adult phase (reviewed by Thorson 1950; Crisp 1984; Strathmann 1993). Given the scale of ocean currents, larval propagules have the potential to interconnect distant populations (Scheltema 1986; Lessios et al. 1998; Mora and Sale 2002); however, determining the extent of inter-population connectivity for individual species is diYcult given that larval dispersal is a complex result of multiple processes, and tracking marine larvae has proven to be diYcult due to their small size and high mortality (Cowen et al. 2000; Levin 2006). Nonetheless, determining the degree to which populations interact is critical for understanding how species are formed (Hedgecock 1986; Palumbi 1994; Meyer et al. 2005), how communities are maintained (Sale and Kritzer 2003) and how conservation eVorts should be prioritized (Bowen 1999; Palumbi 2003). In recent literature, larval duration ha
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