Intraspecific diversity of fission yeast mitochondrial genomes

Abstract

ABSTRACTThe fission yeastSchizosaccharomyces pombeis an important model organism, but its natural diversity and evolutionary history remain under-studied. In particular, the population genomics of theS. pombemitochondrial genome (mitogenome) has not been thoroughly investigated. Here, we assembled the complete circular-mapping mitogenomes of 192S. pombeisolatesde novo, and found that these mitogenomes belong to 69 non-identical sequence types ranging from 17618 bp to 26910 bp in length. Using the assembled mitogenomes, we identified 20 errors in the reference mitogenome and discovered two previously unknown mitochondrial introns. Analysing sequence diversity of these 69 types of mitogenomes revealed two highly distinct clades, with only three mitogenomes exhibiting signs of inter-clade recombination. This diversity pattern suggests that currently availableS. pombeisolates descend from two long-separated ancestral lineages. This conclusion is corroborated by the diversity pattern of the recombination-repressedK-region located between donor mating-type locimat2andmat3in the nuclear genome. We estimated that the two ancestralS. pombelineages diverged about 31 million generations ago. These findings shed new light on the evolution ofS. pombeand the datasets generated in this study will facilitate future research on genome evolution.