Article

Lessios HA, Robertson DR.. Crossing the impassable: genetic connections in 20 reef fishes across the eastern Pacific barrier. Proc R Soc B Biol Sci 273: 2201-2208

Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Panama.
Proceedings of the Royal Society B: Biological Sciences (Impact Factor: 5.05). 10/2006; 273(1598):2201-8. DOI: 10.1098/rspb.2006.3543
Source: PubMed

ABSTRACT

The 'impassable' Eastern Pacific Barrier (EPB), ca 5000 km of deep water separating the eastern from the central Pacific, is the World's widest marine biogeographic barrier. Sequencing of mitochondrial DNA in 20 reef fish morphospecies encountered on both sides of the barrier revealed cryptic speciation in two. Among the other 18 species only two showed significant differentiation (as revealed by haplotype networks and FST statistics) between the eastern and the central Pacific. Coalescence analyses indicated that genetic similarity in the 18 truly transpacific species resulted from different combinations of ages of most recent invasion and of levels of recurrent gene flow, with estimated times of initial separation ranging from approximately 30000 to 1 Myr (ago). There is no suggestion of simultaneous interruptions of gene flow among the species. Migration across the EPB was previously thought to be exclusively eastward, but our evidence showed two invasions from east to west and eight cases in which subsequent gene flow possibly proceeded in the same direction. Thus, the EPB is sporadically permeable to propagules originating on either side.

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Available from: Harilaos Lessios, May 12, 2014
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    • "For all species, we targeted the mtDNA control region (CR) to infer genetic patterns using DNA extraction and amplification protocols detailed inMirams et al. (2011). A suitable length of CR proved difficult to amplify for A. triostegus, so we used ATPase subunit 6 and 8 (ATP6-8) amplified with ATP8.2 and CO3.2 (Lessios & Robertson, 2006). Amplicons were purified, sequenced, and sequences were manually checked and aligned as perLiggins et al. (2015). "
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    ABSTRACT: AimTo determine which seascape features have shaped the spatial genetic patterns of coral reef fishes, and to identify common patterns among species related to dispersal traits [egg type and pelagic larval duration (PLD)].LocationIndian and Pacific Oceans, including the Indo-Australian Archipelago.Methods We sampled coral reef fishes with differing dispersal traits (Pomacentrus coelestis, Dascyllus trimaculatus, Hailchoeres hortulanus and Acanthurus triostegus) and characterized spatial (mtDNA) genetic patterns using AMOVA-clustering and measures of genetic differentiation. Similarity in the spatial genetic patterns among species was assessed using the congruence among distance matrices method and the seascape features associated with the genetic differentiation of each species were identified using multiple regression of distance matrices (MRDM) and stepwise model selection.ResultsSimilar spatial genetic patterns were found for P. coelestis and H. hortulanus, despite their differing egg type (benthic versus pelagic). MRDM indicated that geographical distance was underlying their correlated genetic patterns. Species with pelagic eggs (A. triostegus and H. hortulanus) also had correlated patterns of genetic differentiation (Dest); however, a common underlying seascape feature could not be inferred. Additionally, the common influence of the Torres Strait and the Lydekker/Weber's line was identified for the genetic patterns of differentiation for P. coelestis and A. triostegus, despite their differing dispersal traits, and the uncorrelated spatial genetic patterns of these species.Main conclusionsOur study demonstrates the value of a quantitative, hypothesis-testing framework in comparative phylogeography. We found that dispersal traits (egg type and PLD) did not predict which species had similar spatial genetic patterns or which seascape features were associated with these patterns. Furthermore, even in the absence of visually similar, or correlated spatial genetic patterns, our approach enabled us to identify seascape features that had a common influence on the spatial genetic patterns of co-distributed species.
    Full-text · Article · Feb 2016 · Journal of Biogeography
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    • "Flotsam may function as a habitat substitute for fish in transition from a pelagic to a demersal life stage (Hunter & Mitchell, 1967), acting as a nursery refuge for juvenile reef fishes that have not yet located the reef habitat at the end of the pelagic-larval stage (Kingsford, 1993; Wells & Rooker, 2004). Large expanses of open ocean represent essentially impassable barriers to terrestrial and near-shore marine organisms that are unable to survive in the pelagic realm, or that have either no pelagic dispersal stage or one of short duration (Lessios & Robertson, 2006; Kleiber et al., 2011). For reef fishes, rafts can provide a suitable substratum at the stage when they would normally settle into benthic habitats, and thus can potentially enhance the probability of long-distance dispersal (Mora et al., 2001; Robertson et al., 2004). "
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    Full-text · Article · Jul 2015 · Journal of Biogeography
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    • "The SST over the latter period averaged ∼ 0.6 °C warmer than the preceding 15 years (consistent with Figure 14d in Rayner et al., 2006). The colonisation of an oceanic archipelago by a littoral species in historical times represents a notable example of the effectiveness of sporadic larval dispersal events in suitable climatic conditions (Lessios and Robertson, 2006). The temperature rise that affected the North-East Atlantic sea surface waters caused an impact on the circulation patterns around the Azores. "
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    Full-text · Article · Jul 2015 · Heredity
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