Persistence of high-level heteroplasmy through biparental transmission of a selfish mitochondrion in Drosophila paulistorum

• Heteroplasmy, or the coexistence of multiple mitotypes in an individual, has during recent years been shown to be more common in animals than previously anticipated. However, cases of stable, high-titer heteroplasmy are still relatively rare, as are systems with consistent paternal mitochondrial inheritance. In this study, we sequenced and assembled the full mitochondrial genomes of 23 Neotropical Drosophila lines belonging to six species of the willistoni group and three of the saltans group and discovered that 40% the 13 sequenced Drosophila paulistorum lines, are persistently heteroplasmic. We further showed that the mitochondria of D. paulistorum are polyphyletic, forming two clades, a and b, and that mitochondria of the a2 clade are exclusively found in heteroplasmic flies. Genomic analysis indicates that a2 is a functional mitochondrion, with no signs of loss of function mutations. Even so, our results demonstrate that a2 displays unusual features, including lack of titer response to energetic demands, higher titer in males than females, and consistent biparental transmission due to rapid replication during early embryo development. Together these features indicate that a2 might be a selfish mitochondrion that persists due to efficient biparental transmission.Using the assembled genomes, we reconstructed the evolutionary history of mitochondria in the willistoni subgroup and identified signs of multiple mitochondrial losses, gains and introgressions. The data indicated an a-like mitochondrial ancestor in the willistoni subgroup, with the b mitochondrion likely being acquired through introgression from an unidentified donor. We hypothesize that the selfish characteristics of a2 might have emerged as a response to competition for inheritance with the introgressed b

Ämnesord

NATURVETENSKAP  -- Biologi -- Evolutionsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Evolutionary Biology (hsv//eng)

Nyckelord

Biologi med inriktning mot molekylär evolution

Biology with specialization in Molecular Evolution

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)