The Molecular Phylogenetics of Tuco-Tucos (genusCtenomys,Rodentia: Octodontidae) Suggests an Early Burst of Speciation

• Published in: Molecular phylogenetics and evolution 1998-02, Vol.9 (1), p.88-99
• Main Authors: Lessa, Enrique P, Cook, Joseph A
• Format: Article
• Language: English
• Subjects: Animals; Base Composition; Ctenomys; cytochrome b; Cytochrome b Group - analysis; Cytochrome b Group - genetics; DNA, Mitochondrial - analysis; DNA, Mitochondrial - genetics; Evolution, Molecular; Genetic Variation; mitochondrial DNA; Molecular Sequence Data; Octodontidae; Phylogeny; Rats; Rodentia - genetics
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1006/mpev.1997.0445

Variation in the nucleotide sequence of the entire mitochondrial cytochrome b gene (1140 bp) was examined for 27 individuals representing 13 species of South American rodents of the generaCtenomys, Octodontomys, Tympanoctomys,andSpalacopus.Representatives of the family Echimyidae,EuryzygomatomysandMesomys,were used as outgroups to test the monophyly of the Octodontinae and Ctenomyinae. Relationships among species of tuco-tucos (genusCtenomys) were also examined including representatives of the three described subgenera and the two sperm morphs. Reciprocal monophyly of the Octodontinae and Ctenomyinae is strongly supported. Several basal relationships among species of the genusCtenomysare poorly resolved, suggesting the possibility of a hard polytomy due to a rapid and potentially simultaneous radiation early in the history of the genus. In other cases, clades within the Ctenomyinae previously identified on the basis of allozymes, chromosomes, parasites, or skull morphology were supported. Calibrations based on the fossil record suggest that the mitochondrial cytochrome b of these caviomorphs has evolved at a rapid rate, comparable to those proposed forMus-Rattus,and three to four times higher than ungulate rates.