Genome rearrangements and pervasive meiotic drive cause hybrid infertility in fission yeast.
Bottom Line: Hybrid sterility is one of the earliest postzygotic isolating mechanisms to evolve between two recently diverged species.Two of these driving loci are linked by a chromosomal translocation and thus constitute a novel type of paired meiotic drive complex.Our study reveals how quickly multiple barriers to fertility can arise.
Affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.Show MeSH
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Mentions: This shows the numbers of each parental and recombinant class that were used to calculate recombination frequencies in Sk/Sp hybrids. These data are shown in simplified form in Figure 4—figure supplement 2. We crossed Sk and Sp strains to measure recombination frequencies between the indicated loci. Both parental and recombinant classes illustrate the effects of meiotic drive on the inheritance of each locus. In each cross, Sk-derived alleles are overrepresented. Sk/Sp cM were calculated from the data shown using Haldane’s formula and the Sp cM were calculated using the genome average of 0.16 cM/ kilobase (Smith, 2009; Young et al., 2002) because crossover frequencies are relatively uniform in Sp and most of the intervals are too large to be measured directly. *In the SZY142x180 cross, not all progeny were used to calculate recombination frequencies between lys7 and other markers. This was because the cross contained both lys7− and lys1− alleles. The lys7+lys1− and lys7−lys1− genotypes could not be distinguished because they have the same phenotype. For that reason, we considered only Lys1+ (G418 sensitive) progeny so that we could use the Lys phenotype to genotype lys7. In all crosses, only spores containing one copy of the assayed chromosome were considered.
Affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.