Résumé
Freshwaters represent less than 1% of Earth's surface and 0.02% of
available aquatic habitable volume, but host nearly half of the 35,500
known species of bony fishes. Ostariophysan fishes represent 70% of all
freshwater fishes with ca. 12,000 species distributed in five speciose
orders. They constitute a large radiation whose internal phylogenetic
relationships are still intensively debated. To better understand their
early evolutionary history and origin, we reconstructed their phylogenetic
relationships through a dense taxonomic sampling and the combined use of
complete mitochondrial genomes and sequences of four nuclear genes.
Maximum Likelihood of phylogenetic reconstructions and time tree estimates
were applied to a data set consisting of 687 ostariophysan species for a
total of 21,701 aligned positions, including 15,707 variable sites, and a
Maximum Likelihood of model-based estimation of ancestral areas was used
to reconstruct the early evolution of Otophysi. We produced a highly
supported hypothesis of phylogenetic relationships among Otophysi, which
points to the importance of plate tectonics in triggering several
divergence events jointly with several subsequent range rearrangements,
further consistent with the contraction of the tropical belt that started
at the end of the Cretaceous and lasted throughout the Paleogene. The
divergence of Cypriniformes and Characiphysi results from the joint
influence of the separation of Laurasia and Gondwana, while the origin of
Characiphysi is located in West Gondwana, and the subsequent expansion of
the group cannot be explained without considering transcontinental
dispersal.