Molecular systematics of the South American caviomorph rodents: relationships among species and genera in the family Octodontidae

• Published in: Molecular phylogenetics and evolution Vol. 26; no. 3; pp. 476 - 489
• Main Authors: Honeycutt, Rodney L, Rowe, Diane L, Gallardo, Milton H
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2003
• Subjects: 12S rRNA; Abrocomidae; Aconaemys; Animals; Base Sequence; Caviomorph rodents; Ctenomyidae; Echimyidae; Environment; Evolution, Molecular; Genetic Variation; Growth hormone; Likelihood Functions; Molecular clocks; Molecular phylogeny; Molecular Sequence Data; Myocastoridae; Octodon; Octodontidae; Octodontomys; Octomys; Phylogeny; Receptors, Somatotropin - genetics; RNA, Ribosomal - genetics; Rodentia - classification; Rodentia - genetics; rRNA 12S; South America; Spalacopus; Tympanoctomys; South America; 12S rRNA; Molecular phylogeny; Caviomorph rodents; Growth hormone; Octodontidae; Molecular clocks
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1016/S1055-7903(02)00368-8

Nucleotide sequences from mitochondrial (12S rRNA) and nuclear (growth hormone receptor) genes were used to investigate phylogenetic relationships among South American hystricognath rodents of the superfamily Octodontoidea, with special emphasis on the family Octodontidae. Relationships among most taxa were well resolved by a combined analysis of both genes, and the molecular phylogeny was used to address several long-standing phylogenetic problems. The family Abrocomidae was the most basal lineage within the superfamily Octodontoidea,
sensu stricto, and the family Ctenomyidae was sister to the family Octodontidae, followed by a monophyletic group containing the families Myocastoridae and Echimyidae. A basic dichotomy was observed within the family Octodontidae. The Argentine desert specialists,
Tympanoctomys and
Octomys, grouped separate from
Octodontomys, which was sister to a clade containing a monophyletic
Octodon and a clade represented by species of
Aconaemys and
Spalacopus.
Aconaemys was paraphyletic relative to
Spalacopus. The phylogeny was used as an interpretive framework for an examination of variation in several non-molecular characters. The primitive diploid number for most of the octodontoids was determined to be between 46 and 56, and the primitive genome size 8.2
pg. Members of the Octodontidae appeared to be derived from an ancestral stock occupying lower elevations in scrub habitat. Furthermore, estimates of divergence time from the molecular data provided a temporal perspective for changes in plant communities, which demonstrated turnover and diversification in response to climatic and geologic events occurring in the Miocene through the Pleistocene.