Hybridization and the origin of new yeast lineages

Abstract

Hybrids originate from the mating of two diverged organisms, resulting in novel lineages that have chimeric genomes. Hybrids may exhibit unique phenotypic traits that are not necessarily intermediate between those present in the progenitors. These unique traits may enable them to thrive in new environments. Many hybrid lineages have been discovered among yeasts in the Saccharomycotina, of which many have industrial or clinical relevance, but this might reflect a bias towards investigating species with relevance to humans. Hybridization has also been proposed to be at the root of the whole genome duplication in the lineage leading to Saccharomyces cerevisiae. Thus hybridization seems to have played a prominent role in the evolution of Saccharomycotina yeasts, although it is still unclear how common this evolutionary process has been during the evolution of this and other fungal clades. Similarly, the evolutionary aftermath of hybridization, including implications at the genomic, transcriptional, physiological, or ecological levels remain poorly understood. In this review I survey recent findings from genomic analysis of yeast hybrids of industrial or clinical relevance, and discuss the evolutionary implications of genomic hybridization for the origin of new lineages, including when such hybridization results in a whole genome duplication.

Species-wide transposable element repertoires retrace the evolutionary history of theSaccharomyces cerevisiaehost

“…Interestingly, hybridization events can lead to new TE variants and this reveals some possible long-term impact of natural hybridization on the TE landscape. By analogy with the transgressive phenotypic traits that arise through hybridization [63,64], these new TE repertoires can therefore being shaped during the so-called reticulated evolution [65]. Exploration of species that result from hybridization events, exhibit admixed populations or contain recursive hybrids [66] will therefore be insightful to dissect the formation, the evolution and the impact of these newly emerging TE repertoires.…”

Hybridization Outcomes Have Strong Genomic and Environmental Contingencies

“…One of the best-documented cases are the species in the genus of the model microbe Saccharomyces budding yeast. Interspecies hybridization has featured prominently in Saccharomyces' ancient (Marcet-Houben and Gabaldón 2015;Peris et al 2017) and recent (Gallone et al 2019;Libkind et al 2011;Peris et al 2014) evolutionary history (reviewed in Boynton and Greig 2014;Gabaldón 2020).…”

Patterns and impacts of nonvertical evolution in eukaryotes: a paradigm shift

“…However, since it involves a specific mechanism (i.e., cell fusion and combination of two complete genomes) and has a number of known particularities, I will here treat hybridization separately, restricting HGT to the transfer of genes by means other than mating mechanisms. According to the degree of divergence and the amount of gene flow between the parental species, I have previously defined three types of hybrid genetic zones 60 that may lead to different outcomes (see Fig. 4 for details).…”

“…Left panel represents the three possible hybrid zones, as described in Ref. 60. The square indicates a space of connectivity ( x ‐axis, the amount of gene flow) and genetic relatedness ( y ‐axis, genetic divergence) between putative lineages.…”