Historical colonization and demography of the Mediterranean damselfish, Chromis chromis

Authors

  • VERA S. DOMINGUES,

    Corresponding author
    1. Instituto Superior de Psicologia Aplicada, Unidade de Investigação em Eco-Etologia, R. Jardim do Tabaco 34, 1149-041 Lisboa, Portugal,
    2. Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 100 Shaffer Road, Santa Cruz, 95060, California, USA,
    3. IMAR/DOP, Universidade dos Açores, Cais de Santa Cruz-9901-862 Horta, Açores, Portugal
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  • GIUSEPPE BUCCIARELLI,

    1. Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 100 Shaffer Road, Santa Cruz, 95060, California, USA,
    2. Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy,
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  • VITOR C. ALMADA,

    1. Instituto Superior de Psicologia Aplicada, Unidade de Investigação em Eco-Etologia, R. Jardim do Tabaco 34, 1149-041 Lisboa, Portugal,
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  • GIACOMO BERNARDI

    1. Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 100 Shaffer Road, Santa Cruz, 95060, California, USA,
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Vera S. Domingues, Fax: +351 218860954; E-mail: veradomingues@ispa.pt

Abstract

The desiccation of the Mediterranean Sea during the Messinian Salinity Crisis 6.0–5.3 million years ago (Ma), caused a major extinction of the marine ichthyofauna of the Mediterranean. This was followed by an abrupt replenishment of the Mediterranean from the Atlantic after the opening of the Strait of Gibraltar. In this study, we combined demographic and phylogeographic approaches using mitochondrial and nuclear DNA markers to test the alternative hypotheses of where (Atlantic or Mediterranean) and when (before or after the Messinian Salinity Crisis) speciation occurred in the Mediterranean damselfish, Chromis chromis. The closely related geminate transisthmian pair Chromis multilineata and Chromis atrilobata was used as a way of obtaining an internally calibrated molecular clock. We estimated C. chromis speciation timing both by determining the time of divergence between C. chromis and its Atlantic sister species Chromis limbata (0.93–3.26 Ma depending on the molecular marker used, e.g. 1.23–1.39 Ma for the control region), and by determining the time of coalescence for C. chromis based on mitochondrial control region sequences (0.14–0.21 Ma). The time of speciation of C. chromis was always posterior to the replenishment of the Mediterranean basin, after the Messinian Salinity Crisis. Within the Mediterranean, C. chromis population structure and demographic characteristics revealed a genetic break at the Peloponnese, Greece, with directional and eastbound gene flow between western and eastern groups. The eastern group was found to be more recent and with a faster growing population (coalescent time = 0.09–0.13 Ma, growth = 485.3) than the western group (coalescent time = 0.13–0.20 Ma, growth = 325.6). Our data thus suggested a western origin of C. chromis, most likely within the Mediterranean. Low sea water levels during the glacial periods, the hydrographic regime of the Mediterranean and dispersal restriction during the short pelagic larval phase of C. chromis (18–19 days) have probably played an important role in C. chromis historical colonization.

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