Postglacial migration shaped the genomic diversity and global distribution of the wild ancestor of lager-brewing hybrids

LANGDON, QUINN K.; PERIS, DAVID; EIZAGUIRRE, JUAN I.; OPULENTE, DANA A.; BUH, KELLY V.; SYLVESTER, KAYLA; JARZYNA, MARTIN; RODRÍGUEZ, MARÍA E.; LOPES, CHRISTIAN A.; LIBKIND, DIEGO; HITTINGER, CHRIS TODD

PLOS Genetics

plos

Lugar: San Francisco; Año: 2020 vol. 16

The wild, cold-adapted parent of hybrid lager-brewing yeasts, Saccharomyces eubayanus,has a complex and understudied natural history. The exploration of this diversity can beused both to develop new brewing applications and to enlighten our understanding of thedynamics of yeast evolution in the wild. Here, we integrate whole genome sequence andphenotypic data of 200 S. eubayanus strains, the largest collection known to date. S.eubayanus has a multilayered population structure, consisting of two major populations thatare further structured into six subpopulations. Four of these subpopulations are found exclusivelyin the Patagonian region of South America; one is found predominantly in Patagoniaand sparsely in Oceania and North America; and one is specific to the Holarctic ecozone.Plant host associations differed between subpopulations and between S. eubayanus and itssister species, Saccharomyces uvarum. S. eubayanus is most abundant and geneticallydiverse in northern Patagonia, where some locations harbor more genetic diversity than isfound outside of South America, suggesting that northern Patagonia east of the Andes wasa glacial refugium for this species. All but one subpopulation shows isolation-by-distance,and gene flow between subpopulations is low. However, there are strong signals of ancientand recent outcrossing, including two admixed lineages, one that is sympatric with and onethat is mostly isolated from its parental populations. Using our extensive biogeographicaldata, we build a robust model that predicts all known and a handful of additional regions ofthe globe that are climatically suitable for S. eubayanus, including Europe where host accessibilityand competitive exclusion by other Saccharomyces species may explain its continuedelusiveness. We conclude that this industrially relevant species has rich naturaldiversity with many factors contributing to its complex distribution and natural history.