Molecular phylogeny of the springhare, Pedetes capensis, based on mitochondrial DNA sequences

The phylogenetic position of the Pedetidae, represented by a single speciesPedetes capensis, is controversial, reflecting in part the retention ofboth Hystricomorphous and Sciurognathous characteristics in this rodent. Inan attempt to clarify the species evolutionary relationships, mtDNA genesequences from 10 rodent species (representing seven families) wereanalyzed using phenetic, parsimony, and maximum-likelihood methods ofphylogenetic inference; the rabbit, Oryctolagus cuniculus (OrderLagomorpha), and cow, Bos taurus (Order Artiodactyla), were used asoutgroups. Investigation of 714 base pairs of the protein-coding cytochromeb gene indicate strong base bias at the third codon position withsignificant rate heterogeneity evident between the three structural domainsof this gene. Similar analyses conducted on 816 base pairs of the 12S rRNAgene revealed a transversion bias in the loop sections of all taxa. Thecytochrome b gene sequences proved useful in resolving associations betweenclosely related species but failed to produce consistent tree topologies atthe family level. In contrast, phylogenetic analysis of the 12S rRNA generesulted in strong support for the clustering ofPedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusionof the Hystricidae/Thryonomyidae and Sciuridae, a finding which isconcordant with studies of rodent fetal membranes as well as reproductiveand other anatomical features.