The mitochondrial genomes of three skippers: Insights into the evolution of the family Hesperiidae (Lepidoptera)

Abstract

We sequenced the mitogenomes of Astictopterus jama, Isoteinon lamprospilus and Notocrypta curvifascia to obtain further insight into the mitogenomic architecture evolution and performed phylogenetic reconstruction using 29 Hesperiidae mitogenome sequences. The complete mitogenome sequences of A. jama, I. lamprospilus and N. curvifascia are 15,430, 15,430 and 15,546 bp in size, respectively. All contain 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and an A + T-rich region. Nucleotide composition is A + T biased, and the majority of the protein-coding genes exhibit a negative AT-skew, which is reflected in the nucleotide composition, codon, and amino acid usage. The A + T-rich region is comprised of nonrepetitive sequences, including the motif ATAGA followed by a poly-T stretch, a microsatellite-like element next to the ATTTA motif, and a poly-A adjacent to tRNAs. Although most genes evolve under a strong purifying selection, the entire nad gene family (especially nad6) exhibits somewhat relaxed purifying selection, and atp8, evolving under a highly relaxed selection, is an outlier in the family Hesperiidae. Several different approaches relatively consistently indicated that nad6, atp8 and nad4 are comparatively fast-evolving genes in this family, which may have implications for future phylogenetic, population genetics and species diagnostics studies. For phylogenetic analyses of Hesperiidae, we tested a few datasets, and found that the one comprising all 37 genes produced the highest node support, indicating that the inclusion of RNAs improves the phylogenetic signal. Results indicate that subfamilies Euschemoninae, Heteropterinae, and Coeliadinae are monophyletic with strong nodal support, but Pyrginae and Eudaminae are paraphyletic. Finally, we confirm that A. jama and I. lamprospilus are close relatives.