Structure and evolution of the mitochondrial control region of the pollen beetleMeligethes thalassophilus(Coleoptera: Nitidulidae)

Abstract

The organization of the mitochondrial DNA (mtDNA) control region (CR) of the pollen beetle Meligethes thalassophilus is described. This mtDNA CR represents the longest sequenced for beetles so far, since the entire nucleotide sequence ranges from approximately 5000 to approximately 5500 bp. The CR of M. thalassophilus is organized in three distinct domains: a conserved domain near the tRNAIle gene, a variable domain flanking the 12S rRNA gene, and a relatively large central tandem array made up of a variable number of approximately 170 bp repeats that is responsible for the intraspecific length variation observed. Like other CRs found in insects, the M. thalassophilus CR contains two long homopolymeric runs that may be involved in mtDNA replication. Furthermore, conserved stem-and-loop structures in the repetitive domain were identified and their possible role in generating length variation is examined. Intraspecific comparison of the tandem repeat elements of M. thalassophilus suggests mechanisms of concerted evolution leading to homogenization of the repetitive region. The utility of such an array of tandem repeats as a genetic marker for assessing population-level variability and evolutionary relationships among populations is discussed. Finally, the technical difficulties found in isolating the mtDNA CR in beetles are remarked upon.