A thirty million year-old inherited heteroplasmy.
Due to essentially maternal inheritance and a bottleneck effect during early oogenesis, newly arising mitochondrial DNA (mtDNA) mutations segregate rapidly in metazoan female germlines. Consequently, heteroplasmy (i.e. the mixture of mtDNA genotypes within an organism) is generally resolved to homoplasmy within a few generations. Here, we report an exceptional transpecific heteroplasmy (predicting an alanine/valine alloacceptor tRNA change) that has been stably inherited in oniscid crustaceans for at least thirty million years. Our results suggest that this heteroplasmy is stably transmitted across generations because it occurs within mitochondria and therefore escapes the mtDNA bottleneck that usually erases heteroplasmy. Consistently, at least two oniscid species possess an atypical trimeric mitochondrial genome, which provides an adequate substrate for the emergence of a constitutive intra-mitochondrial heteroplasmy. Persistence of a mitochondrial polymorphism on such a deep evolutionary timescale suggests that balancing selection may be shaping mitochondrial sequence evolution in oniscid crustaceans.
Doublet
Vincent
V
Université de Poitiers, Laboratoire Ecologie, Evolution, Symbiose, UMR CNRS 6556, Poitiers, France.
Souty-Grosset
Catherine
C
Bouchon
Didier
D
Cordaux
Richard
R
Marcadé
Isabelle
I
D000818:Animals; D001135:Armadillos / Q000235:genetics*; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics; D005580:Fossils; D018740:Genetic Heterogeneity; D016678:Genome; D008928:Mitochondria / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020641:Polymorphism, Single Nucleotide; D023121:RNA, Messenger, Stored / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics
D004272:DNA, Mitochondrial; D023121:RNA, Messenger, Stored; D012343:RNA, Transfer