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Abstract(s)
The northeastern Atlantic and the Mediterranean
Sea share geological histories and display great faunal
affinities. The majority of the Mediterranean species have
Atlantic origins, with a few species with tropical affinities.
These include the parrotfish Sparisoma cretense and the
wrasse Thalassoma pavo that are restricted to the subtropical
northeastern Atlantic, the Macaronesian archipelagos
(Azores, Madeira, and Canaries) and the southern Mediterranean.
The Pleistocene glaciations have been described as having different effects on the fauna of the two regions. During
glacial peaks, Mediterranean waters remained warmer
than those of the adjacent Atlantic. Within the eastern
Atlantic, the effects of Pleistocene glaciations were differentiated.
Here, we perform a comparative analysis focusing on
T. pavo and S. cretense populations from the northeastern
Atlantic and the Mediterranean to assess the effects of Pleistocene
glaciations in these two species. Sequences from the
mitochondrial control region were obtained and analyzed
combining phylogeographic and demographic approaches.
Gene flow between Atlantic and Mediterranean populations
was shown to be very high. The Mediterranean populations
of T. pavo and S. cretense showed high levels of genetic
diversity, even in the eastern basin, pointing to an ancient
colonization event. This suggests that both species must
have been able to persist in the Mediterranean during the
cold Pleistocene periods. Historical migration estimates
revealed a Mediterranean towards Atlantic trend in the case
of T. pavo, which may reflect the re-colonization of areas in
the Atlantic by fish that survived the cold phases in relatively
warmer Mediterranean refugia. Our data also showed
that within the Macaronesian Archipelagos, migrations
occurred from Madeira towards the Azores, for both T. pavo
and S. cretense, thus supporting a post-glacial colonization
of the Azores by fish that persisted in the warmer region of
Madeira. Similar geographic distributions, thermal affinities,
and means of dispersion for T. pavo and S. cretense resulted
in a similar response to the effects of Pleistocene glaciations,
as evidenced by identical phylogeographic patterns.
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Citation
Marine Biology, 154, 465-474