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1. Epigenetics Research in Evolutionary Biology: Perspectives on Timescales and Mechanisms

   https://doi.org/10.1093/molbev/msae170  

   Yi, Soojin V (September 2024, Molecular Biology and Evolution)

   Gaut, Brandon (Ed.)

   Abstract Epigenetics research in evolutionary biology encompasses a variety of research areas, from regulation of gene expression to inheritance of environmentally mediated phenotypes. Such divergent research foci can occasionally render the umbrella term “epigenetics” ambiguous. Here I discuss several areas of contemporary epigenetics research in the context of evolutionary biology, aiming to provide balanced views across timescales and molecular mechanisms. The importance of epigenetics in development is now being assessed in many nonmodel species. These studies not only confirm the importance of epigenetic marks in developmental processes, but also highlight the significant diversity in epigenetic regulatory mechanisms across taxa. Further, these comparative epigenomic studies have begun to show promise toward enhancing our understanding of how regulatory programs evolve. A key property of epigenetic marks is that they can be inherited along mitotic cell lineages, and epigenetic differences that occur during early development can have lasting consequences on the organismal phenotypes. Thus, epigenetic marks may play roles in short-term (within an organism's lifetime or to the next generation) adaptation and phenotypic plasticity. However, the extent to which observed epigenetic variation occurs independently of genetic influences remains uncertain, due to the widespread impact of genetics on epigenetic variation and the limited availability of comprehensive (epi)genomic resources from most species. While epigenetic marks can be inherited independently of genetic sequences in some species, there is little evidence that such “transgenerational inheritance” is a general phenomenon. Rather, molecular mechanisms of epigenetic inheritance are highly variable between species. 

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2. Integrating microbiome science and evolutionary medicine into animal health and conservation

   https://doi.org/10.1111/brv.13030  

   Bornbusch, Sally L.; Power, Michael L.; Schulkin, Jay; Drea, Christine M.; Maslanka, Michael T.; Muletz‐Wolz, Carly R. (November 2023, Biological Reviews)

   ABSTRACT Microbiome science has provided groundbreaking insights into human and animal health. Similarly, evolutionary medicine – the incorporation of eco‐evolutionary concepts into primarily human medical theory and practice – is increasingly recognised for its novel perspectives on modern diseases. Studies of host–microbe relationships have been expanded beyond humans to include a wide range of animal taxa, adding new facets to our understanding of animal ecology, evolution, behaviour, and health. In this review, we propose that a broader application of evolutionary medicine, combined with microbiome science, can provide valuable and innovative perspectives on animal care and conservation. First, we draw on classic ecological principles, such as alternative stable states, to propose an eco‐evolutionary framework for understanding variation in animal microbiomes and their role in animal health and wellbeing. With a focus on mammalian gut microbiomes, we apply this framework to populations of animals under human care, with particular relevance to the many animal species that suffer diseases linked to gut microbial dysfunction (e.g. gut distress and infection, autoimmune disorders, obesity). We discuss diet and microbial landscapes (i.e. the microbes in the animal's external environment), as two factors that are (i) proposed to represent evolutionary mismatches for captive animals, (ii) linked to gut microbiome structure and function, and (iii) potentially best understood from an evolutionary medicine perspective. Keeping within our evolutionary framework, we highlight the potential benefits – and pitfalls – of modern microbial therapies, such as pre‐ and probiotics, faecal microbiota transplants, and microbial rewilding. We discuss the limited, yet growing, empirical evidence for the use of microbial therapies to modulate animal gut microbiomes beneficially. Interspersed throughout, we propose 12 actionable steps, grounded in evolutionary medicine, that can be applied to practical animal care and management. We encourage that these actionable steps be paired with integration of eco‐evolutionary perspectives into our definitions of appropriate animal care standards. The evolutionary perspectives proposed herein may be best appreciated when applied to the broad diversity of species under human care, rather than when solely focused on humans. We urge animal care professionals, veterinarians, nutritionists, scientists, and others to collaborate on these efforts, allowing for simultaneous care of animal patients and the generation of valuable empirical data. 

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3. Using targeted genome methylation for crop improvement

   https://doi.org/10.1093/jxb/eraf131  

   Wang, Zhibo; Bart, Rebecca_S; Lechon, ed., Tamara (March 2025, Journal of Experimental Botany)

   Abstract Genome editing allows scientists to specifically change the DNA sequence of an organism. This powerful technology now fuels basic biology discovery and tangible crop improvement efforts. There is a less well understood layer of information encoded in genomes, known collectively as ‘epigenetics’, that impacts gene expression, without changing the DNA sequence. Epigenetic processes allow organisms to rapidly respond to environmental fluctuation. Like genome editing, recent advances have demonstrated that it is possible to edit the epigenome of a plant and cause heritable phenotypic changes. In this review, we aim to specifically consider the unique advantages that targeted epigenome editing might provide over existing biotechnology tools. This review is aimed at a broad audience. We begin with a high-level overview of the tools currently available for crop improvement. Next, we present a more detailed overview of the key discoveries that have been made in recent years, primarily using the model system Arabidopsis, new efforts to extend targeted methylation to crop plants, the current status of the technology, and the challenges that remain to realize the full potential of targeted epigenome editing. We end with a forward-looking commentary on how epi-alleles might interface with breeding programs across a variety of crops. 

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4. Phylogenomics of the Epigenetic Toolkit Reveals Punctate Retention of Genes across Eukaryotes

   https://doi.org/10.1093/gbe/evaa198  

   Weiner, Agnes K; Cerón-Romero, Mario A; Yan, Ying; Katz, Laura A (December 2020, Genome Biology and Evolution)

   Archibald, John (Ed.)

   Abstract Epigenetic processes in eukaryotes play important roles through regulation of gene expression, chromatin structure, and genome rearrangements. The roles of chromatin modification (e.g., DNA methylation and histone modification) and non-protein-coding RNAs have been well studied in animals and plants. With the exception of a few model organisms (e.g., Saccharomyces and Plasmodium), much less is known about epigenetic toolkits across the remainder of the eukaryotic tree of life. Even with limited data, previous work suggested the existence of an ancient epigenetic toolkit in the last eukaryotic common ancestor. We use PhyloToL, our taxon-rich phylogenomic pipeline, to detect homologs of epigenetic genes and evaluate their macroevolutionary patterns among eukaryotes. In addition to data from GenBank, we increase taxon sampling from understudied clades of SAR (Stramenopila, Alveolata, and Rhizaria) and Amoebozoa by adding new single-cell transcriptomes from ciliates, foraminifera, and testate amoebae. We focus on 118 gene families, 94 involved in chromatin modification and 24 involved in non-protein-coding RNA processes based on the epigenetics literature. Our results indicate 1) the presence of a large number of epigenetic gene families in the last eukaryotic common ancestor; 2) differential conservation among major eukaryotic clades, with a notable paucity of genes within Excavata; and 3) punctate distribution of epigenetic gene families between species consistent with rapid evolution leading to gene loss. Together these data demonstrate the power of taxon-rich phylogenomic studies for illuminating evolutionary patterns at scales of >1 billion years of evolution and suggest that macroevolutionary phenomena, such as genome conflict, have shaped the evolution of the eukaryotic epigenetic toolkit. 

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5. Avenues of reef-building coral acclimatization in response to rapid environmental change

   https://doi.org/10.1242/jeb.239319  

   Putnam, Hollie M. (February 2021, Journal of Experimental Biology)

   null (Ed.)

   ABSTRACT The swiftly changing climate presents a challenge to organismal fitness by creating a mismatch between the current environment and phenotypes adapted to historic conditions. Acclimatory mechanisms may be especially crucial for sessile benthic marine taxa, such as reef-building corals, where climate change factors including ocean acidification and increasing temperature elicit strong negative physiological responses such as bleaching, disease and mortality. Here, within the context of multiple stressors threatening marine organisms, I describe the wealth of metaorganism response mechanisms to rapid ocean change and the ontogenetic shifts in organism interactions with the environment that can generate plasticity. I then highlight the need to consider the interactions of rapid and evolutionary responses in an adaptive (epi)genetic continuum. Building on the definitions of these mechanisms and continuum, I also present how the interplay of the microbiome, epigenetics and parental effects creates additional avenues for rapid acclimatization. To consider under what conditions epigenetic inheritance has a more substantial role, I propose investigation into the offset of timing of gametogenesis leading to different environmental integration times between eggs and sperm and the consequences of this for gamete epigenetic compatibility. Collectively, non-genetic, yet heritable phenotypic plasticity will have significant ecological and evolutionary implications for sessile marine organism persistence under rapid climate change. As such, reef-building corals present ideal and time-sensitive models for further development of our understanding of adaptive feedback loops in a multi-player (epi)genetic continuum. 

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