The rate of whole-genome duplication can be accelerated by hybridization (original) (raw)
Related papers
The neutral rate of whole-genome duplication varies among yeast species and their hybrids
Nature Communications, 2021
Hybridization and polyploidization are powerful mechanisms of speciation. Hybrid speciation often coincides with whole-genome duplication (WGD) in eukaryotes. This suggests that WGD may allow hybrids to thrive by increasing fitness, restoring fertility and/or increasing access to adaptive mutations. Alternatively, it has been suggested that hybridization itself may trigger WGD. Testing these models requires quantifying the rate of WGD in hybrids without the confounding effect of natural selection. Here we show, by measuring the spontaneous rate of WGD of more than 1300 yeast crosses evolved under relaxed selection, that some genotypes or combinations of genotypes are more prone to WGD, including some hybrids between closely related species. We also find that higher WGD rate correlates with higher genomic instability and that WGD increases fertility and genetic variability. These results provide evidence that hybridization itself can promote WGD, which in turn facilitates the evoluti...
Spontaneous whole-genome duplication restores fertility in interspecific hybrids
Nature Communications
Interspecies hybrids often show some advantages over parents but also frequently suffer from reduced fertility, which can sometimes be overcome through sexual reproduction that sorts out genetic incompatibilities. Sex is however inefficient due to the low viability or fertility of hybrid offspring and thus limits their evolutionary potential. Mitotic cell division could be an alternative to fertility recovery in species such as fungi that can also propagate asexually. Here, to test this, we evolve in parallel and under relaxed selection more than 600 diploid yeast inter-specific hybrids that span from 100,000 to 15 M years of divergence. We find that hybrids can recover fertility spontaneously and rapidly through whole-genome duplication. These events occur in both hybrids between young and well-established species. Our results show that the instability of ploidy in hybrid is an accessible path to spontaneous fertility recovery.
Evolution, 2010
Whole-genome duplication has shaped the genomes of extant lineages ranging from unicellular fungi to vertebrates, and its association with several species-rich taxa has fuelled interest in its potential as a catalyst for speciation. One well-established model for the evolution of reproductive isolation involves the reciprocal loss of redundant genes at different loci in allopatric populations. Whole-genome duplication simultaneously doubles the entire gene content of an organism, resulting in massive levels of genetic redundancy and potential for reciprocal gene loss that may produce postzygotic reproductive isolation. Following whole-genome duplication, different populations can potentially change or lose gene function at different duplicate loci. If such populations come back into contact any F1 hybrids that are formed may suffer reduced fertility as some of the gametes they produce may not carry a full complement of functional genes. This reduction in hybrid fertility will be directly proportional to the number of divergently resolved loci between the populations. In this work, we demonstrate that initially identical populations of allotetraploid yeast subjected to mutagenesis rapidly evolve postzygotic reproductive isolation, consistent with the divergent loss of function of redundant gene copies.
Does hybridization between divergent progenitors drive whole-genome duplication?
Molecular Ecology, 2009
Hybridization and whole-genome duplication are both potential mechanisms of rapid speciation which sometimes act in concert. Recent surveys, showing that homoploid hybrid species tend to be derived from parents that are less evolutionarily divergent than parents of polyploid hybrid species (allopolyploids), have been interpreted as supporting a hypothesis that high divergence between hybridizing species drives whole-genome duplication. Here we argue that such conclusions stem from problems in sampling (especially the omission of autopolyploids) and null model selection, and underestimate the importance of selection. The data simply demonstrate that hybridization between divergent parents has a higher probability of successfully producing a species if followed by polyploidization.
2012
Background Interspecific hybridization occurs in every eukaryotic kingdom. While hybrid progeny are frequently at a selective disadvantage, in some instances their increased genome size and complexity may result in greater stress resistance than their ancestors, which can be adaptively advantageous at the edges of their ancestors' ranges. While this phenomenon has been repeatedly documented in the field, the response of hybrid populations to long-term selection has not often been explored in the lab.
Yeast as a Window into Changes in Genome Complexity Due to Polyploidization
Polyploidy and Genome Evolution, 2012
Due to the long history of genetic analyses in yeasts and their experimental tractability, the yeast genome duplication provides important perspectives on the genome and population-level processes that follow wholegenome duplication (WGD). We discuss the history of the discovery of the Saccharomyces cerevisiae WGD, with special emphasis on the role of comparative genomics in its analysis. We then explore models of the WGD shaped population and species divergence, both at a gene level (e.g., Dobzhansky-Muller incompatibility) and from the perspective of recent work on secondary allopolyploidy in Saccharomyces pastorianus. Finally, we explore the selective forces that act on the WGD-produced paralogs and shape their patterns of loss and retention. In addition to discussing the dosage balance hypothesis as it applies to the yeast WGD, we explore the role of the WGD in shaping several complex metabolic and regulatory phenotypes.
Defects Arising From Whole-Genome Duplications in Saccharomyces cerevisiae
Genetics, 2004
Comparisons among closely related species have led to the proposal that the duplications found in many extant genomes are the remnants of an ancient polyploidization event, rather than a result of successive duplications of individual chromosomal segments. If this interpretation is correct, it would support Ohno's proposal that polyploidization drives evolution by generating the genetic material necessary for the creation of new genes. Paradoxically, analysis of contemporary polyploids suggests that increased ploidy is an inherently unstable state. To shed light on this apparent contradiction and to determine the effects of nascent duplications of the entire genome, we generated isogenic polyploid strains of the budding yeast Saccharomyces cerevisiae. Our data show that an increase in ploidy results in a marked decrease in a cell's ability to survive during stationary phase in growth medium. Tetraploid cells die rapidly, whereas isogenic haploids remain viable for weeks. Unlike haploid cells, which arrest growth as unbudded cells, tetraploid cells continue to bud and form mitotic spindles in stationary phase. The stationary-phase death of tetraploids can be prevented by mutations or conditions that result in growth arrest. These data show that whole-genome duplications are accompanied by defects that affect viability and subsequent survival of the new organism.
Genomic Background Predicts the Fate of Duplicated Genes: Evidence From the Yeast Genome
Genetics, 2004
Gene duplication with subsequent divergence plays a central role in the acquisition of genes with novel function and complexity during the course of evolution. With reduced functional constraints or through positive selection, these duplicated genes may experience accelerated evolution. Under the model of subfunctionalization, loss of subfunctions leads to complementary acceleration at sites with two copies, and the difference in average rate between the sequences may not be obvious. On the other hand, the classical model of neofunctionalization predicts that the evolutionary rate in one of the two duplicates is accelerated. However, the classical model does not tell which of the duplicates experiences the acceleration in evolutionary rate. Here, we present evidence from the Saccharomyces cerevisiae genome that a duplicate located in a genomic region with a low-recombination rate is likely to evolve faster than a duplicate in an area of high recombination. This observation is consistent with population genetics theory that predicts that purifying selection is less effective in genomic regions of low recombination (Hill-Robertson effect). Together with previous studies, our results suggest the genomic background (e.g., local recombination rate) as a potential force to drive the divergence between nontandemly duplicated genes. This implies the importance of structure and complexity of genomes in the diversification of organisms via gene duplications.