Mitochondrial DNA reveals Pleistocenic colonisation of the Mediterranean by loggerhead turtles (Caretta caretta)

Marcel Clusa, Carlos Carreras, Marta Pascual, Andreas Demetropoulos, Dimitris Margaritoulis, Alan F. Rees, Abdulmaula A. Hamza, Mona Khalil, Monica Aureggi, Yaniv Levy, Ogüz Türkozan, Adolfo Marco, Alex Aguilar, Luis Cardona

Research output: Contribution to journalArticlepeer-review


As the loggerhead turtle (Caretta caretta) is a philopatric species with a strong genetic structure, the analysis of mtDNA can be used to track evolutionary and colonisation events. In this study we use a genetic approach to understand the population structure of C. caretta in the Mediterranean Sea and to test whether loggerheads could have colonised the Mediterranean during the Pleistocene and survived the cold phases in warm refugia. We amplified a long mtDNA D-loop fragment (815. bp) from 168 dead hatchlings sampled from a selection of rookeries in the Eastern Mediterranean: Libya, Israel, Lebanon, Cyprus and Greece. Previously published data from Turkey and Calabria (Southern Italy) were also included in the analyses. The population nesting in Libya emerged as the oldest population in the Mediterranean, dating from the Pleistocene ca. 65,000. years ago (20,000-200,000). This reveals that the Libyan population might have settled in the Mediterranean basin before the end of the last glacial period. The remaining nesting sites, except Calabria, were subsequently colonised as the population expanded. The populations nesting in Eastern Turkey and Western Greece settled ca. 30,000. years ago (10,000-100,000), whereas the remaining populations originated as a result of a more recent Holocenic expansion. As Calabria presented a unique Atlantic haplotype, found nowhere else in the Mediterranean, we consider this nesting site as the result of an independent colonisation event from the Atlantic and not the recent spread of Mediterranean populations. This reveals that the current genetic structure of C. caretta rookeries in the Mediterranean would be the result of at least two colonisation events from the Atlantic, the oldest one in Libya and a most recent in Calabria, combined with local extinctions during Pleistocenic glaciations and re-colonisations from glacial refugia in Libya, Eastern Turkey and Western Greece.

Original languageEnglish
Pages (from-to)15-24
Number of pages10
JournalJournal of Experimental Marine Biology and Ecology
StatePublished - Jan 2013
Externally publishedYes


  • Caretta caretta
  • Genetic structuring
  • Glacial refugia
  • Molecular clock
  • MtDNA
  • Phylogeography

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


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