Allozymic variation and systematic relationships of the Octodontidae and allied taxa (Mammalia, Rodentia)

Abstract

Genetic variation and the allozymic relationships of five families comprising 23 species of hystricognath rodents were examined using electrophoretic data from 19 presumptive gene loci. Direct-count heterozygosity ranged from 0% to 13.6%, and polymorphism varied from 0% to 36.8%. Fixed allele differences were instrumental for the segregation of taxa as summarized by the Distance Wagner procedure and by majority-rule consensus trees. The monophyly of the Octodontidae, and the family rank of the Abrocomidae and Ctenomyidae is supported by the data. Monotypic Myocastor coypus is not resolved as a distinct family but appeared within the Caviidae. Within the Octodontidae, paraphyly was detected in polytypic Octodon, whereas a high bootstrap value supported the node containing the desert specialists O. mimax (2n = 56) and Tympanoctomys barreare (2n = 102). The implications of allozymic data as a robust phylogenetic signal that connected biochemical associations to the prediction of tetraploidy in T. barrerae are discussed.