Molecular evolution of the control region in feliform carnivores

Abstract

The mitochondrial control region and adjacent tRNA genes were sequenced for nine species of feliform carnivores including eight taxa in the family Felidae and one representative of Herpestidae. Both length and nucleotide site heterogeneity were observed. Length heterogeneity (within and between species) within the Felidae was the result of insertions/deletions in both 3' and 5 tandem arrays of repeats with an average size of 6 bp and 80 bp, respectively. Among carnivores the 5' tandem array was restricted to Felidae, whereas the 3' array occurred in all families examined. Although little evidence of secondary structure was found for the felid 5' repeats, their position and sequence similarity were highly conserved among felid taxa and between felids and unrelated orders of mammals. For instance, felid 5' repeats were 77% similar to tandem repeats found in shrews of the order Insectivora, and portions of the felid 5' repeats were highly similar to single copy sequences seen in other mammalian orders. At the nucleotide sequence level variation along the control region could be subdivided into conserved and variable domains, with all regions demonstrating a strong transitional/transversional bias. No significant rate heterogeneity was observed for the felid control region, and the overall rate of substitution (6.31 x 1 09̄/site/year) was slower by a factor of 10 relative to hominoid primates. Nucleotide sequences were used to examine relationships among the felid taxa, and the resultant phylogeny revealed strong support for a monophyletic Lynx, with relationships among lynx species being highly resolved. These data were compared to other phylogenetic hypotheses for felids derived from morphological and molecular characters, and both congruence and total evidence (combining all characters) were used to evaluate overall support for particular groupings. The control region data were found to be most congruent with findings from other molecular data.