Loss of heterozygosity drives adaptation in hybrid yeast
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PROVIDER: PRJNA376031 | ENA |
REPOSITORIES: ENA
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Project description:CGH arrays for Smukowski Heil, et al MBE 2017. Hybridization is often considered maladaptive, but sometimes hybrids can invade new ecological niches and adapt to novel or stressful environments better than their parents. The genomic changes that occur following hybridization that facilitate genome resolution and/or adaptation are not well understood. Here, we address these questions using experimental evolution of de novo interspecific hybrid yeast Saccharomyces cerevisiae x Saccharomyces uvarum and their parentals. We evolved these strains in nutrient limited conditions for hundreds of generations and sequenced the resulting cultures to identify genomic changes. Analysis of 16 hybrid clones and 16 parental clones identified numerous point mutations, copy number changes, and loss of heterozygosity events, including species biased amplification of nutrient transporters. We focused on a particularly interesting example, in which we saw repeated loss of heterozygosity at the high affinity phosphate transporter gene PHO84 in both intra- and interspecific hybrids. Using allele replacement methods, we tested the fitness of different alleles in hybrid and S. cerevisiae strain backgrounds and found that the loss of heterozygosity is indeed the result of selection on one allele over the other in both S. cerevisiae and the hybrids. This is an example where hybrid genome resolution is driven by positive selection on existing heterozygosity, and demonstrates that even infrequent outcrossing may have lasting impacts on adaptation.
2017-02-21 | GSE95086 | GEO
Project description:Hybridization is often considered maladaptive, but sometimes hybrids can invade new ecological niches and adapt to novel or stressful environments better than their parents. The genomic changes that occur following hybridization that facilitate genome resolution and/or adaptation are not well understood. Here, we examine hybrid genome evolution using experimental evolution of de novo interspecific hybrid yeast Saccharomyces cerevisiae × Saccharomyces uvarum and their parentals. We evolved these strains in nutrient-limited conditions for hundreds of generations and sequenced the resulting cultures identifying numerous point mutations, copy number changes, and loss of heterozygosity (LOH) events, including species-biased amplification of nutrient transporters. We focused on a particularly interesting example, in which we saw repeated LOH at the high-affinity phosphate transporter gene PHO84 in both intra- and interspecific hybrids. Using allele replacement methods, we tested the fitness of different alleles in hybrid and S. cerevisiae strain backgrounds and found that the LOH is indeed the result of selection on one allele over the other in both S. cerevisiae and the hybrids. This is an example where hybrid genome resolution is driven by positive selection on existing heterozygosity and demonstrates that even infrequent outcrossing may have lasting impacts on adaptation.
| S-EPMC5455960 | biostudies-literature
Project description:This experiment is the analysis of the transcriptomes of several hybrid yeast strains obtained by crossing natural (from wine) isolates of S. cerevisiae and S. uvarum. All isolations have been done from hybrid strains growing in exponential phase in YPD. Keywords: Strain comparison
2008-07-15 | GSE9888 | GEO
Project description:This experiment is the analysis of the transcriptomes of several hybrid yeast strains obtained by crossing natural (from wine) isolates of S. cerevisiae and S. uvarum. All isolations have been done from hybrid strains growing in exponential phase in YPD. Keywords: Strain comparison Transcriptomic analysis of three independent replicates of each yeast strain growing in exponential phase. Each replicate has been hybridized on a different macroarray (F19-F22-F24) as indicated in the sample files. A single DNA (S. cerevisiae 3002 wine strain) genomic hybridization, from the same labeling reaction, was done on the same macroarrays for normalization.
2010-06-25 | E-GEOD-9888 | biostudies-arrayexpress
Project description:Telomere behavior in a hybrid yeast
| PRJNA117033 | ENA
Project description:Changes in gene regulation rapidly accumulate between species and may contribute to reproductive isolation through misexpression of genes in interspecific hybrids. Hybrid misexpression, defined by expression levels outside the range of both parental species, is thought to be a result of cis- and trans-acting regulatory changes that interact in the hybrid, or arise from changes in the relative abundance of various tissues or cell types due to defects in developmental. Here, we show that misexpressed genes in a sterile interspecific Saccharomyces yeast hybrid result from a heterochronic shift in the timing of the normal meiotic gene expression program. By tracking nuclear divisions, we find that S. cerevisiae initiates meiosis earlier than its closest known relative, S. paradoxus, yet both species complete meiosis at the same time. Although the hybrid up- and down-regulates genes in a similar manner to both parents, the hybrid meiotic program occurs earlier than both parents. The timing shift results in a heterochronic pattern of misexpression throughout meiosis I and the beginning of meiosis II. Coincident with the timing of misexpression, we find an increase in the relative abundance of opposing cis and trans-acting changes and compensatory changes, as well as a transition from predominantly trans-acting to cis-acting expression divergence over the course of meiosis. However, misexpression does not appear to be a direct consequence of cis- and trans-acting regulatory divergence. Our results demonstrate that hybrid misexpression in yeast results from a heterochronic shift in the meiotic gene expression program.
2013-10-31 | GSE51809 | GEO
Project description:BackgroundHybrids are chimeric organisms with highly plastic heterozygous genomes that may confer unique traits enabling the adaptation to new environments. However, most evolutionary theory frameworks predict that the high levels of genetic heterozygosity present in hybrids from divergent parents are likely to result in numerous deleterious epistatic interactions. Under this scenario, selection is expected to favor recombination events resulting in loss of heterozygosity (LOH) affecting genes involved in such negative interactions. Nevertheless, it is so far unknown whether this phenomenon actually drives genomic evolution in natural populations of hybrids. To determine the balance between selection and drift in the evolution of LOH patterns in natural yeast hybrids, we analyzed the genomic sequences from fifty-five hybrid strains of the pathogenic yeasts Candida orthopsilosis and Candida metapsilosis, which derived from at least six distinct natural hybridization events.ResultsWe found that, although LOH patterns in independent hybrid clades share some level of convergence that would not be expected from random occurrence, there is an apparent lack of strong functional selection. Moreover, while mitosis is associated with a limited number of inter-homeologous chromosome recombinations in these genomes, induced DNA breaks seem to increase the LOH rate. We also found that LOH does not accumulate linearly with time in these hybrids. Furthermore, some C. orthopsilosis hybrids present LOH patterns compatible with footprints of meiotic recombination. These meiotic-like patterns are at odds with a lack of evidence of sexual recombination and with our inability to experimentally induce sporulation in these hybrids.ConclusionsOur results suggest that genetic drift is the prevailing force shaping LOH patterns in these hybrid genomes. Moreover, the observed LOH patterns suggest that these are likely not the result of continuous accumulation of sporadic events-as expected by mitotic repair of rare chromosomal breaks-but rather of acute episodes involving many LOH events in a short period of time.
| S-EPMC10173528 | biostudies-literature
Project description:We compared the genome-wide expression profiles of two yeast species (S. cerevisiae and S. paradoxus) using a two-species microarray that contain species-specific probes and can thus measure the expression levels of the two species simultaneosly. In Addition, we used the array to measure expression levels of the interspecific hybrid of these yeast species, while discriminating between the alleles that correspond to the two parental species. Comparison of the between-species differences and the within-hybrid allele differences allows us to separate cis from trans effects. Also, comparison of the overall expression in the hybrids (both alleles) with their parental species allows us to analyze hybrid over-expression and under-expression. Keywords: comparative transcriptome analysis, hybrid gene expression
2009-04-01 | GSE14708 | GEO