Patterns and processes of molecular evolution critically influence inferences in phylogeny and phylogeography. Within primates, a shift in evolutionary rates has been identified as the rationale for contrasting findings from mitochondrial... more
Patterns and processes of molecular evolution critically influence inferences in phylogeny and phylogeography. Within primates, a shift in evolutionary rates has been identified as the rationale for contrasting findings from mitochondrial and nuclear DNA studies as to the position of Tarsius. While the latter now seems settled, we sequenced complete mitochondrial genomes of three Sulawesi tarsiers (Tarsius dentatus, T. lariang, and T. wallacei) and analyzed substitution rates among tarsiers and other primates to infer driving processes of molecular evolution. We found substantial length polymorphism of the D-loop within tarsier individuals, but little variation of predominant lengths among them, regardless of species. Length variation was due to repetitive elements in the CSB domain-minisatellite motifs of 35 bp length and microsatellite motifs of 6 bp length. Amino acid evolutionary rates were second highest among major primate taxa relative to nucleotide substitution rates. We observed many radical possibly function-altering amino acid changes that were rarely driven by positive selection and thus potentially slightly deleterious or neutral. We hypothesize that the observed pattern of an increased amino acid evolutionary rate in tarsier mitochondrial genomes may be caused by hitchhiking of slightly deleterious mutations with favored D-loop length variants selected for maximizing replication success within the cell or the mitochondrion.
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A 454-FLX low-coverage sequencing approach was used to assemble the mitochondrial genome of Radix balthica. The mtDNA sequence is 13,993 nt long and contains 37 genes (13 protein coding genes, two rRNAs and 22 tRNAs). Four genes, the 12S... more
A 454-FLX low-coverage sequencing approach was used to assemble the mitochondrial genome of Radix balthica. The mtDNA sequence is 13,993 nt long and contains 37 genes (13 protein coding genes, two rRNAs and 22 tRNAs). Four genes, the 12S RNA and seven tRNAs are transcribed in reverse order. The sequence is AT rich (71.3%), similar to other basommatophoran species. Comparison with the most closely related mt genomes available (Biomphalaria glabrata and Biomphalaria tenagophila) revealed identical gene orders except for five tRNAs. Next generation sequencing proved to be a fast and easy method for sequencing an entire mitochondrial genome.