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Schwartz LC, González VL, Strong EE, Truebano M, Hilbish TJ. Transgressive gene expression and expression plasticity under thermal stress in a stable hybrid zone. Mol Ecol 2024; 33:e17333. [PMID: 38597343 DOI: 10.1111/mec.17333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 02/21/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024]
Abstract
Interspecific hybridization can lead to myriad outcomes, including transgressive phenotypes in which the hybrids are more fit than either parent species. Such hybrids may display important traits in the context of climate change, able to respond to novel environmental conditions not previously experienced by the parent populations. While this has been evaluated in an agricultural context, the role of transgressive hybrids under changing conditions in the wild remains largely unexplored; this is especially true regarding transgressive gene expression. Using the blue mussel species complex (genus Mytilus) as a model system, we investigated the effects of hybridization on temperature induced gene expression plasticity by comparing expression profiles in parental species and their hybrids following a 2-week thermal challenge. Hybrid expression plasticity was most often like one parent or the other (50%). However, a large fraction of genes (26%) showed transgressive expression plasticity (i.e. the change in gene expression was either greater or lesser than that of both parent species), while only 2% were intermediately plastic in hybrids. Despite their close phylogenetic relationship, there was limited overlap in the differentially expressed genes responding to temperature, indicating interspecific differences in the responses to high temperature in which responses from hybrids are distinct from both parent species. We also identified differentially expressed long non-coding RNAs (lncRNAs), which we suggest may contribute to species-specific differences in thermal tolerance. Our findings provide important insight into the impact of hybridization on gene expression under warming. We propose transgressive hybrids may play an important role in population persistence under future warming conditions.
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Affiliation(s)
- Lindsey C Schwartz
- Department of Biological Sciences, The University of South Carolina, Columbia, South Carolina, USA
- Department of Invertebrate Zoology, Smithsonian National Museum of Natural History, Washington, District of Columbia, USA
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana, USA
| | - Vanessa L González
- Informatics and Data Science Center, Smithsonian National Museum of Natural History, Washington, District of Columbia, USA
| | - Ellen E Strong
- Department of Invertebrate Zoology, Smithsonian National Museum of Natural History, Washington, District of Columbia, USA
| | - Manuela Truebano
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | - Thomas J Hilbish
- Department of Biological Sciences, The University of South Carolina, Columbia, South Carolina, USA
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2
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The evolutionary and ecological potential of yeast hybrids. Curr Opin Genet Dev 2022; 76:101958. [PMID: 35834944 DOI: 10.1016/j.gde.2022.101958] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/18/2022] [Accepted: 06/21/2022] [Indexed: 01/19/2023]
Abstract
Recent findings in yeast genetics and genomics have advanced our understanding of the evolutionary potential unlocked by hybridization, especially in the genus Saccharomyces. We now have a clearer picture of the prevalence of yeast hybrids in the environment, their ecological and evolutionary history, and the genetic mechanisms driving (and constraining) their adaptation. Here, we describe how the instability of hybrid genomes determines fitness across large evolutionary scales, highlight new hybrid strain engineering techniques, and review tools for comparative hybrid genome analysis. The recent push to take yeast research back 'into the wild' has resulted in new genomic and ecological resources. These provide an arena for quantitative genetics and allow us to investigate the architecture of complex traits and mechanisms of adaptation to rapidly changing environments. The vast genetic diversity of hybrid populations can yield insights beyond those possible with isogenic lines. Hybrids offer a limitless supply of genetic variation that can be tapped for industrial strain improvement but also, combined with experimental evolution, can be used to predict population responses to future climate change - a fundamental task for biologists.
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3
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Pfennig A, Lachance J. Hybrid fitness effects modify fixation probabilities of introgressed alleles. G3 GENES|GENOMES|GENETICS 2022; 12:6583188. [PMID: 35536195 PMCID: PMC9258535 DOI: 10.1093/g3journal/jkac113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 04/28/2022] [Indexed: 11/12/2022]
Abstract
Hybridization is a common occurrence in natural populations, and introgression is a major source of genetic variation. Despite the evolutionary importance of adaptive introgression, classical population genetics theory does not take into account hybrid fitness effects. Specifically, heterosis (i.e. hybrid vigor) and Dobzhansky–Muller incompatibilities influence the fates of introgressed alleles. Here, we explicitly account for polygenic, unlinked hybrid fitness effects when tracking a rare introgressed marker allele. These hybrid fitness effects quickly decay over time due to repeated backcrossing, enabling a separation-of-timescales approach. Using diffusion and branching process theory in combination with computer simulations, we formalize the intuition behind how hybrid fitness effects affect introgressed alleles. We find that hybrid fitness effects can significantly hinder or boost the fixation probability of introgressed alleles, depending on the relative strength of heterosis and Dobzhansky–Muller incompatibilities effects. We show that the inclusion of a correction factor (α, representing the compounded effects of hybrid fitness effects over time) into classic population genetics theory yields accurate fixation probabilities. Despite having a strong impact on the probability of fixation, hybrid fitness effects only subtly change the distribution of fitness effects of introgressed alleles that reach fixation. Although strong Dobzhansky–Muller incompatibility effects may expedite the loss of introgressed alleles, fixation times are largely unchanged by hybrid fitness effects.
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Affiliation(s)
- Aaron Pfennig
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - Joseph Lachance
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332, USA
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4
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Bendixsen DP, Frazão JG, Stelkens R. Saccharomyces yeast hybrids on the rise. Yeast 2021; 39:40-54. [PMID: 34907582 DOI: 10.1002/yea.3684] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/19/2021] [Accepted: 12/08/2021] [Indexed: 12/23/2022] Open
Abstract
Saccharomyces hybrid yeasts are receiving increasing attention as a powerful model system to understand adaptation to environmental stress and speciation mechanisms, using experimental evolution and omics techniques. We compiled all genomic resources available from public repositories of the eight recognized Saccharomyces species and their interspecific hybrids. We present the newest numbers on genomes sequenced, assemblies, annotations, and sequencing runs, and an updated species phylogeny using orthogroup inference. While genomic resources are highly skewed towards Saccharomyces cerevisiae, there is a noticeable movement to use wild, recently discovered yeast species in recent years. To illustrate the degree and potential causes of reproductive isolation, we reanalyzed published data on hybrid spore viabilities across the entire genus and tested for the role of genetic, geographic, and ecological divergence within and between species (28 cross types and 371 independent crosses). Hybrid viability generally decreased with parental genetic distance likely due to antirecombination and negative epistasis, but notable exceptions emphasize the importance of strain-specific structural variation and ploidy differences. Surprisingly, the viability of crosses within species varied widely, from near reproductive isolation to near-perfect viability. Geographic and ecological origins of the parents predicted cross viability to an extent, but with certain caveats. Finally, we highlight publication trends in the field and point out areas of special interest, where hybrid yeasts are particularly promising for innovation through research and development, and experimental evolution and fermentation.
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Affiliation(s)
- Devin P Bendixsen
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
| | - João G Frazão
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Rike Stelkens
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
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Madden AA, Lahue C, Gordy CL, Little JL, Nichols LM, Calvert MD, Dunn RR, Smukowski Heil C. Sugar-seeking insects as a source of diverse bread-making yeasts with enhanced attributes. Yeast 2021; 39:108-127. [PMID: 34687090 DOI: 10.1002/yea.3676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/08/2021] [Accepted: 10/17/2021] [Indexed: 11/10/2022] Open
Abstract
Insects represent a particularly interesting habitat in which to search for novel yeasts of value to industry. Insect-associated yeasts have the potential to have traits relevant to modern food and beverage production due to insect-yeast interactions, with such traits including diverse carbohydrate metabolisms, high sugar tolerance, and general stress tolerance. Here, we consider the potential value of insect-associated yeasts in the specific context of baking. We isolated 63 yeast strains from 13 species of hymenoptera from the United States, representing 37 yeast species from 14 genera. Screening for the ability to ferment maltose, a sugar important for bread production, resulted in the identification of 13 strains of Candida, Lachancea, and Pichia species. We assessed their ability to leaven dough. All strains produced baked loaves comparable to a commercial baking strain of Saccharomyces cerevisiae. The same 13 strains were also grown under various sugar and salt conditions relevant to osmotic challenges experienced in the manufacturing processes and the production of sweet dough. We show that many of these yeast strains, most notably strains of Lachancea species, grow at a similar or higher rate and population size as commercial baker's yeast. We additionally assessed the comparative phenotypes and genetics of insect-associated S. cerevisiae strains unable to ferment maltose and identified baking-relevant traits, including variations in the HOG1 signaling pathway and diverse carbohydrate metabolisms. Our results suggest that non-conventional yeasts have high potential for baking and, more generally, showcase the success of bioprospecting in insects for identifying yeasts relevant for industrial uses.
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Affiliation(s)
- Anne A Madden
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA.,The Microbe Institute, Everett, Massachusetts, USA
| | - Caitlin Lahue
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA.,Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA.,University of North Carolina Chapel-Hill, Chapel Hill, North Carolina, USA
| | - Claire L Gordy
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Joy L Little
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Lauren M Nichols
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Martha D Calvert
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA.,Department of Food Science and Technology, Virginia Tech, Blacksburg, Virginia, USA
| | - Robert R Dunn
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Caiti Smukowski Heil
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA
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