The mitochondrial genome of Melipona fasciculata and Melipona quadrifasciata: molecular evolution dynamics in stingless bees (Hymenoptera: Meliponini) mitogenomes

Abstract

Mitochondrial genomes serve as crucial data sources for evolutionary studies and the development of species conservation markers. However, due to the vast diversity of stingless bees, mitogenome research has been limited. Here, we assembled and annotated the mitochondrial genomes of Melipona fasciculata and M. quadrifasciata for a comparative analysis to explore the evolution of stingless bee (Meliponini) mtDNA. DNA sequences for M. fasciculata were obtained through total DNA sequencing, while those for M. quadrifasciata were sourced from public databases. The mitochondrial genomes of M. fasciculata and M. quadrifasciata span 15,207 bp (AT% = 87.08) and 15,341 bp (AT% = 87.95), respectively, and contain the typical 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes found in insects. Comparative analysis with previously sequenced Meliponini genomes revealed a 10% increase in GC% in Indo-Malay/Australasian stingless bees, particularly in PCG regions. Meliponini mitogenomes displayed a high level of complex rearrangement events with five rearrangement blocks. Among the eight mitogenomes studied, tRNA genes exhibited greater mobility and involvement in genomic rearrangement events. NADH dehydrogenase subunit genes in the genera Melipona, Tetragonula, and LepidoTrigona showed higher nucleotide diversity compared to the standard Cox1 DNA barcode gene. We propose nad1, nad2, nad3, nad5, and atp6 as potential barcode genes for species discrimination within the Meliponini group. This study unveils two novel mitochondrial genomes and provides compelling evidence of the intricate evolution of Meliponini mitochondrial genomes.