title: Independent adaptation to riverine habitats allowed survival of ancient cetacean lineages.
abstract: The four species of "river dolphins" are associated with six separate great river systems on three subcontinents and have been grouped for more than a century into a single taxon based on their similar appearance. However, several morphologists recently questioned the monophyly of that group. By using phylogenetic analyses of nucleotide sequences from three mitochondrial and two nuclear genes, we demonstrate with statistical significance that extant river dolphins are not monophyletic and suggest that they are relict species whose adaptation to riverine habitats incidentally insured their survival against major environmental changes in the marine ecosystem or the emergence of Delphinidae.
authors.affiliation: Unit of Evolutionary Genetics, and Unit of Bioinformatics, Free University of Brussels, Institute of Molecular Biology and Medicine, B-6041 Gosselies, Belgium.
authors.forename: I
authors.initials: I
authors.lastname: Cassens
authors.forename: S
authors.initials: S
authors.lastname: Vicario
authors.forename: V G
authors.initials: VG
authors.lastname: Waddell
authors.forename: H
authors.initials: H
authors.lastname: Balchowsky
authors.forename: D
authors.initials: D
authors.lastname: Van Belle
authors.forename: W
authors.initials: W
authors.lastname: Ding
authors.forename: C
authors.initials: C
authors.lastname: Fan
authors.forename: R S
authors.initials: RS
authors.lastname: Mohan
authors.forename: P C
authors.initials: PC
authors.lastname: Simões-Lopes
authors.forename: R
authors.initials: R
authors.lastname: Bastida
authors.forename: A
authors.initials: A
authors.lastname: Meyer
authors.forename: M J
authors.initials: MJ
authors.lastname: Stanhope
authors.forename: M C
authors.initials: MC
authors.lastname: Milinkovitch
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics*; D002591:Cetacea / Q000502:physiology*; D004272:DNA, Mitochondrial / Q000235:genetics; D008969:Molecular Sequence Data
chemical_list: D004272:DNA, Mitochondrial