Abstract
Complete mitochondrial genomes contain large and diverse datasets for species delineation. To better understand the divergence of the two morphologically indistinguishable weevil species in Curculionini, we first sequenced and compared their complete mitochondrial genomes. The complete mitochondrial genomes of Curculio chinensis and Curculio sp. were 19,713 bp with an A + T content of 76.61% and 19,216 bp with an A + T content of 76.85%, respectively. All 37 of the typical mitochondrial genes were determined in both species. The 13 protein sequences of the two species shared high homology (about 90%) except for ATP8 (73.08%). The differences in secondary structure of ATP8 were the number of possible proteins and nucleic acid binding sites. There were 22 and 15 mismatched base-pairs in the tRNA secondary structures from C. chinensis and Curculio sp., respectively. Maximum Likelihood and Bayesian analyses indicated that Curculio sp. is a novel species closely related to C. chinensis. The divergence time estimation suggests that Cryptorhynchinae and Curculionini lines diverged in the Cenozoic Period, while C. chinensis and Curculio sp. diverged at 6.7079 (95% CI 5–13) Mya. This study demonstrates the utility of using complete mitochondrial gene sets for phylogenetic analysis and enhances our understanding of the genetic basis for the evolution of the Curculionini.
Highlights
Complete mitochondrial genomes contain large and diverse datasets for species delineation
Ktze. (Theaceae) which have been widely cultivated as important economic trees in China, and it is often identified as Curculio chinensis Chevrolat[1,2,3,4]
They are associated with metabolism, life cycle, and apoptosis and are abundant in energy consuming tissues related to essential biological functions[6,7]
Summary
Were 19,713 bp and 19,216 long, respectively (GenBank accessions MG728094 and MG728095) (Table S1) The genomes of both species contained all 37 typical animal mitochondrial genes, including 13 protein-coding genes, 22 tRNA genes, and two rRNA genes (Fig. S1). No gene rearrangement was observed in either species compared with the putative ancestral and sibling superfamily arrangement (Fig. S1) This is consistent with the lack of rearrangement found in all sequenced Curculionini species[8,11]. The mitochondrial genome of C. chinensis has intergenic spacers with lengths ranging from 1 to 103 bp in 24 different locations. Nine pairs of genes were directly adjacent one another, which included the pairs rrnL-trnV and trnV-rrnS (Table 2) In both species, the longest intergenic spacer was located between trnS2 and NAD1. In C. chinensis PCGs, only one gene (NAD1) used ATA, seven used ATT, and five used
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