Mitochondrial DNA intra-individual variation in a bumblebee species: A challenge for evolutionary studies and molecular identification

• Published in: Mitochondrion 2020-07, Vol.53, p.243-254
• Main Authors: Ricardo, Paulo Cseri, Françoso, Elaine, Arias, Maria Cristina
• Format: Article
• Language: English
• Subjects: Animals; Bees - classification; Bees - genetics; Bombus morio; COI; DNA, Mitochondrial - genetics; Evolution, Molecular; Heteroplasmy; Mitochondria - genetics; mtDNA; NUMTs; Phylogeny; Sequence Analysis, DNA - veterinary
• ISSN: 1567-7249; 1872-8278
• DOI: 10.1016/j.mito.2020.06.007

•Heteroplasmy is a common condition in the bumblebee Bombus morio.•Shared heteroplasmic haplotypes can mislead inferences about genetic structure and differentiation.•Heteroplasmy and (mostly) NUMTs can affect species identification through DNA barcoding.•mtDNA sequences should be used cautiously, and evidence of heteroplasmy and NUMTs should not be neglected. Mitochondrial DNA (mtDNA) regions have been widely used as molecular markers in evolutionary studies and species identification. However, the presence of heteroplasmy and NUMTs may represent obstacles. Heteroplasmy is a state where an organism has different mitochondrial haplotypes. NUMTs are nuclear pseudogenes originating from mtDNA sequences transferred to nuclear DNA. Evidences of heteroplasmy were already verified in the bumblebee Bombus morio in an earlier study. The present work investigated in more detail the presence of intra-individual haplotypes variation in this species. Heteroplasmy was detected in individuals from all the ten sampled locations, with an average of six heteroplasmic haplotypes per individual. In addition, some of these heteroplasmic haplotypes were shared among individuals from different locations, suggesting the existence of stable heteroplasmy in B. morio. These results demonstrated that heteroplasmy is likely to affect inferences based on mtDNA analysis, especially in phylogenetic, phylogeographic and population genetics studies. In addition, NUMTs were also detected. These sequences showed divergence of 2.7% to 12% in relation to the mitochondrial haplotypes. These levels of divergence could mislead conclusions in evolutionary studies and affect species identification through DNA barcoding.