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Luo M, Hu J. Alternative splicing in parallel evolution and the evolutionary potential in sticklebacks. J Anim Ecol 2024. [PMID: 39056271 DOI: 10.1111/1365-2656.14157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 06/28/2024] [Indexed: 07/28/2024]
Abstract
Repeatability of adaptation to similar environments provides opportunity to evaluate the predictability of natural selection. While many studies have investigated gene expression differences between populations adapted to contrasting environments, the role of post-transcriptional processes such as alternative splicing has rarely been evaluated in the context of parallel adaptation. To address the aforementioned knowledge gap, we reanalysed transcriptomic data from three pairs of threespine stickleback (Gasterosteus aculeatus) ecotypes adapted to marine or freshwater environment. First, we identified genes with repeated expression or splicing divergence across ecotype pairs, and compared the genetic architecture and biological processes between parallelly expressed and parallelly spliced loci. Second, we analysed the extent to which parallel adaptation was reflected at gene expression and alternative splicing levels. Finally, we tested how the two axes of transcriptional variation differed in their potential for evolutionary change. Although both repeated differential splicing and differential expression across ecotype pairs showed tendency for parallel divergence, the degree of parallelism was lower for splicing than expression. Furthermore, parallel divergences in splicing and expression were likely to be associated with distinct cis-regulatory genetic variants and functionally unique set of genes. Finally, we found that parallelly spliced genes showed higher nucleotide diversity than parallelly expressed genes, indicating splicing is less susceptible to genetic variation erosion during parallel adaptation. Our results provide novel insight into the role of splicing in parallel adaptation, and underscore the contribution of splicing to the evolutionary potential of wild populations under environmental change.
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Affiliation(s)
- Man Luo
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, China
| | - Juntao Hu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, China
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Ren X, Zhao J, Hu J. Non-concordant epigenetic and transcriptional responses to acute thermal stress in western mosquitofish (Gambusia affinis). Mol Ecol 2024:e17332. [PMID: 38529738 DOI: 10.1111/mec.17332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 02/28/2024] [Accepted: 03/18/2024] [Indexed: 03/27/2024]
Abstract
Climate change is intensifying the frequency and severity of extreme temperatures. Understanding the molecular mechanisms underlying the ability to cope with acute thermal stress is key for predicting species' responses to extreme temperature events. While many studies have focused on the individual roles of gene expression, post-transcriptional processes and epigenetic modifications in response to acute thermal stress, the relative contribution of these molecular mechanisms remains unclear. The wide range of thermal limits of western mosquitofish (Gambusia affinis) provides an opportunity to explore this interplay. Here, we quantified changes in gene expression, alternative splicing, DNA methylation and microRNA (miRNA) expression in muscle tissue dissected from mosquitofish immediately after reaching high (CTmax) or low thermal limit (CTmin). Although the numbers of genes showing expression and splicing changes in response to acute temperature stress were small, we found a possibly larger and non-redundant role of splicing compared to gene expression, with more genes being differentially spliced (DSGs) than differentially expressed (DEGs), and little overlap between DSGs and DEGs. We also identified a small proportion of CpGs showing significant methylation change (i.e. differentially methylated cytosines, DMCs) in fish at thermal limits; however, there was no overlap between DEGs and genes annotated with DMCs in both CTmax and CTmin experiments. The weak interplay between epigenetic modifications and gene expression was further supported by our discoveries of no differentially expressed miRNAs. These findings provide novel insights into the relative role of different molecular mechanisms underlying immediate responses to extreme temperatures and demonstrate non-concordant responses of epigenetic and transcriptional mechanisms to acute temperature stress.
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Affiliation(s)
- Xingyue Ren
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, P. R. China
| | - Junjie Zhao
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, P. R. China
| | - Juntao Hu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, P. R. China
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Bernatchez L, Ferchaud AL, Berger CS, Venney CJ, Xuereb A. Genomics for monitoring and understanding species responses to global climate change. Nat Rev Genet 2024; 25:165-183. [PMID: 37863940 DOI: 10.1038/s41576-023-00657-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2023] [Indexed: 10/22/2023]
Abstract
All life forms across the globe are experiencing drastic changes in environmental conditions as a result of global climate change. These environmental changes are happening rapidly, incur substantial socioeconomic costs, pose threats to biodiversity and diminish a species' potential to adapt to future environments. Understanding and monitoring how organisms respond to human-driven climate change is therefore a major priority for the conservation of biodiversity in a rapidly changing environment. Recent developments in genomic, transcriptomic and epigenomic technologies are enabling unprecedented insights into the evolutionary processes and molecular bases of adaptation. This Review summarizes methods that apply and integrate omics tools to experimentally investigate, monitor and predict how species and communities in the wild cope with global climate change, which is by genetically adapting to new environmental conditions, through range shifts or through phenotypic plasticity. We identify advantages and limitations of each method and discuss future research avenues that would improve our understanding of species' evolutionary responses to global climate change, highlighting the need for holistic, multi-omics approaches to ecosystem monitoring during global climate change.
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Affiliation(s)
- Louis Bernatchez
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, Quebec, Canada
| | - Anne-Laure Ferchaud
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, Quebec, Canada.
- Parks Canada, Office of the Chief Ecosystem Scientist, Protected Areas Establishment, Quebec City, Quebec, Canada.
| | - Chloé Suzanne Berger
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, Quebec, Canada
| | - Clare J Venney
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, Quebec, Canada
| | - Amanda Xuereb
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, Quebec, Canada
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de Carvalho CF, Slate J, Villoutreix R, Soria-Carrasco V, Riesch R, Feder JL, Gompert Z, Nosil P. DNA methylation differences between stick insect ecotypes. Mol Ecol 2023; 32:6809-6823. [PMID: 37864542 DOI: 10.1111/mec.17165] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/12/2023] [Accepted: 09/25/2023] [Indexed: 10/23/2023]
Abstract
Epigenetic mechanisms, such as DNA methylation, can influence gene regulation and affect phenotypic variation, raising the possibility that they contribute to ecological adaptation. Beginning to address this issue requires high-resolution sequencing studies of natural populations to pinpoint epigenetic regions of potential ecological and evolutionary significance. However, such studies are still relatively uncommon, especially in insects, and are mainly restricted to a few model organisms. Here, we characterize patterns of DNA methylation for natural populations of Timema cristinae adapted to two host plant species (i.e. ecotypes). By integrating results from sequencing of whole transcriptomes, genomes and methylomes, we investigate whether environmental, host and genetic differences of these stick insects are associated with methylation levels of cytosine nucleotides in the CpG context. We report an overall genome-wide methylation level for T. cristinae of ~14%, with methylation being enriched in gene bodies and impoverished in repetitive elements. Genome-wide DNA methylation variation was strongly positively correlated with genetic distance (relatedness), but also exhibited significant host-plant effects. Using methylome-environment association analysis, we pinpointed specific genomic regions that are differentially methylated between ecotypes, with these regions being enriched for genes with functions in membrane processes. The observed association between methylation variation and genetic relatedness, and with the ecologically important variable of host plant, suggests a potential role for epigenetic modification in T. cristinae adaptation. To substantiate such adaptive significance, future studies could test whether methylation can be transmitted across generations and the extent to which it responds to experimental manipulation in field and laboratory studies.
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Affiliation(s)
| | - Jon Slate
- School of Biosciences, University of Sheffield, Sheffield, UK
| | | | | | - Rüdiger Riesch
- University of Montpellier, CEFE, CNRS, EPHE, IRD, Montpellier, France
- Department of Biological Sciences, Centre for Ecology, Evolution and Behaviour, Royal Holloway University of London, Egham, UK
| | - Jeffrey L Feder
- Department of Biology, Notre Dame University, South Bend, Indiana, USA
| | | | - Patrik Nosil
- School of Biosciences, University of Sheffield, Sheffield, UK
- University of Montpellier, CEFE, CNRS, EPHE, IRD, Montpellier, France
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Venney CJ, Anastasiadi D, Wellenreuther M, Bernatchez L. The Evolutionary Complexities of DNA Methylation in Animals: From Plasticity to Genetic Evolution. Genome Biol Evol 2023; 15:evad216. [PMID: 38015807 PMCID: PMC10701099 DOI: 10.1093/gbe/evad216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/22/2023] [Accepted: 11/22/2023] [Indexed: 11/30/2023] Open
Abstract
The importance of DNA methylation in plastic responses to environmental change and evolutionary dynamics is increasingly recognized. Here, we provide a Perspective piece on the diverse roles of DNA methylation on broad evolutionary timescales, including (i) short-term transient acclimation, (ii) stable phenotypic evolution, and (iii) genomic evolution. We show that epigenetic responses vary along a continuum, ranging from short-term acclimatory responses in variable environments within a generation to long-term modifications in populations and species. DNA methylation thus unlocks additional potential for organisms to rapidly acclimate to their environment over short timeframes. If these changes affect fitness, they can circumvent the need for adaptive changes at the genome level. However, methylation has a complex reciprocal relationship with genetic variation as it can be genetically controlled, yet it can also induce point mutations and contribute to genomic evolution. When habitats remain constant over many generations, or populations are separated across habitats, initially plastic phenotypes can become hardwired through epigenetically facilitated mutagenesis. It remains unclear under what circumstances plasticity contributes to evolutionary outcomes, and when plastic changes will become permanently encoded into genotype. We highlight how studies investigating the evolution of epigenetic plasticity need to carefully consider how plasticity in methylation state could evolve among different evolutionary scenarios, the possible phenotypic outcomes, its effects on genomic evolution, and the proximate energetic and ultimate fitness costs of methylation. We argue that accumulating evidence suggests that DNA methylation can contribute toward evolution on various timescales, spanning a continuum from acclimatory plasticity to genomic evolution.
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Affiliation(s)
- Clare J Venney
- Institut de Biologie Intégrative des Systèmes (IBIS), Département de Biologie, Université Laval, Québec, QC, Canada
| | - Dafni Anastasiadi
- The New Zealand Institute for Plant and Food Research Ltd, Nelson Research Centre, Nelson, New Zealand
| | - Maren Wellenreuther
- The New Zealand Institute for Plant and Food Research Ltd, Nelson Research Centre, Nelson, New Zealand
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Louis Bernatchez
- Institut de Biologie Intégrative des Systèmes (IBIS), Département de Biologie, Université Laval, Québec, QC, Canada
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