Ancestral Admixture Is the Main Determinant of Global Biodiversity in Fission Yeast.

TitleAncestral Admixture Is the Main Determinant of Global Biodiversity in Fission Yeast.
Publication TypeJournal Article
Year of Publication2019
AuthorsTusso, S, Nieuwenhuis, BPS, Sedlazeck, FJ, Davey, JW, Jeffares, DC, Wolf, JBW
JournalMol Biol Evol
Volume36
Issue9
Pagination1975-1989
Date Published2019 Sep 01
ISSN1537-1719
Abstract

Mutation and recombination are key evolutionary processes governing phenotypic variation and reproductive isolation. We here demonstrate that biodiversity within all globally known strains of Schizosaccharomyces pombe arose through admixture between two divergent ancestral lineages. Initial hybridization was inferred to have occurred ∼20-60 sexual outcrossing generations ago consistent with recent, human-induced migration at the onset of intensified transcontinental trade. Species-wide heritable phenotypic variation was explained near-exclusively by strain-specific arrangements of alternating ancestry components with evidence for transgressive segregation. Reproductive compatibility between strains was likewise predicted by the degree of shared ancestry. To assess the genetic determinants of ancestry block distribution across the genome, we characterized the type, frequency, and position of structural genomic variation using nanopore and single-molecule real-time sequencing. Despite being associated with double-strand break initiation points, over 800 segregating structural variants exerted overall little influence on the introgression landscape or on reproductive compatibility between strains. In contrast, we found strong ancestry disequilibrium consistent with negative epistatic selection shaping genomic ancestry combinations during the course of hybridization. This study provides a detailed, experimentally tractable example that genomes of natural populations are mosaics reflecting different evolutionary histories. Exploiting genome-wide heterogeneity in the history of ancestral recombination and lineage-specific mutations sheds new light on the population history of S. pombe and highlights the importance of hybridization as a creative force in generating biodiversity.

DOI10.1093/molbev/msz126
Alternate JournalMol. Biol. Evol.
PubMed ID31225876
PubMed Central IDPMC6736153
Grant ListUM1 HG008898 / HG / NHGRI NIH HHS / United States