Evolutionary perspectives on bee mtDNA from mito-OMICS analyses of a solitary species

The analysis of mitochondrial DNA polymorphism has been applied in multiple organisms to obtain information about species biology, ecology, population dynamics, and evolution. In this manuscript, the complete sequencing and characterization of the mitochondrial genome (mtGenome) of Tetrapedia diversipes are reported and discussed from comparative and evolutionary perspectives among all mtGenomes available for bees so far. The T. diversipes mtGenome is 15,358 bp long and exhibits the typical set of genes and an A+T-rich region of 588 bp. The overall base composition is biased towards A/T (84.3%), with 42.6% A, 41.7% T, 9.8% C, and 5.9% G nucleotides. The obtained data also comprise the mitochondrial DNA methylation and single-nucleotide polymorphic sites of one T. diversipes population. Transcription follows the ``tRNA punctuation{''} model, with at least three primary polycistronic transcripts that are posteriorly processed. Additionally, higher expression rates of the 16S gene suggest the existence of an exclusive transcription site in this region, and the differential expression of the 12S gene between larvae and adults reveals different isoforms for this gene. The sequence order of protein-coding and rRNA genes is conserved across different bee lineages, and differences are restricted to tRNA gene positions. The present results characterize numerous understudied aspects of bee mtGenomes, and a major evolutionary review of this molecule within the group is provided. Therefore, this work is a valuable resource for studying mitochondrial molecular biology and evolution in bees. (AU)