The Role of Epigenetics in Evolution: The Extended Synthesis (original) (raw)
Related papers
Epigenetics and Evolution: An Overview
2010
After many years of neglect, the developmental aspect of heredity and its place in evolution are now receiving attention. In this overview, I discuss the relationship between epigenetic inheritance (mainly cellular epigenetic inheritance) and biological evolution. I point to six effects and implications of epigenetic inheritance that are important for evolutionary studies: (i) evolution can occur along the epigenetic axis without changes in DNA base sequence; (ii) epigenetic inheritance can affect the stability of the selective environment and speed up genetic accommodation; (iii) epigenetic variations can bias and target changes in DNA base sequence, leading to both microand macro-evolutionary changes; (iv) epigenetic inheritance constrains and channels the evolution of ontogeny; (v) epigenetic variations and epigenetic inheritance systems were important during the major evolutionary transitions; (vi) the genetic evolution of epigenetic inheritance systems is an important part of e...
The evolutionary implications of epigenetic inheritance
Interface Focus, 2017
The Modern Evolutionary Synthesis (MS) forged in the mid-twentieth century was built on a notion of heredity that excluded soft inheritance, the inheritance of the effects of developmental modifications. However, the discovery of molecular mechanisms that generate random and developmentally induced epigenetic variations is leading to a broadening of the notion of biological heredity that has consequences for ideas about evolution. After presenting some old challenges to the MS that were raised, among others, by Karl Popper, I discuss recent research on epigenetic inheritance, which provides experimental and theoretical support for these challenges. There is now good evidence that epigenetic inheritance is ubiquitous and is involved in adaptive evolution and macroevolution. I argue that the many evolutionary consequences of epigenetic inheritance open up new research areas and require the extension of the evolutionary synthesis beyond the current neo-Darwinian model.
The hairy problem of epigenetics in evolution
It has long been suspected that epigenetic mechanisms could contribute to heritable phenotypic variation, and thus to the diversity and evolutionary potential of natural populations. In recognition of the growing evidence bearing on this possibility, the National Evolutionary Synthesis Center (Durham, NC) recently hosted an interdisciplinary gathering of epigeneticists, experimental evolutionary ecologists, behavioral ecologists, theoretical population and quantitative geneticists and philosophers of science to discuss methods available to investigate epigenetic variation and epigenetic inheritance, as well as how to evaluate their importance for phenotypic evolution. This vibrant new arena is attracting empirical studies involving natural, non-model systems, including those merging robust ecological experimental design with chemical manipulation of genome-wide DNA methylation with 5-azacytidine or screening for methylation sensitive amplified fragment length polymorphisms (MS-AFLPs) in response to stress, different habitats and natural levels of herbivory. While these studies have convincingly shown correlations between genome wide changes in methylation with external environment, they ultimately are unsatisfying because surveys such as these do not readily translate into changes in expression of specific genes, particularly those that might be suspected to have ecological relevance. In general, across non-model systems with little or no DNA sequence information, it still is quite challenging to actually demonstrate the specific effects of epigenetic modification on ecologically and evolutionarily relevant phenotypes. Scoville et al. (2011) have taken a significant step forward in this direction,identifying a target gene that may be epigenetically modified, adding a remarkable new chapter to the emerging body of work on epigenetic inheritance of trichome density in yellow monkeyflower (Mimulus guttatus).
2018
Studying the phenotypic evolution of organisms in terms of populations of genes and genotypes, the Modern Synthesis (MS) conceptualizes biological evolution in terms of 'inter-organismal' interactions among genes sitting in the different individual organisms that constitute a population. It 'black-boxes' the complex 'intra-organismic' molecular and developmental epigenetics mediating between genotypes and phenotypes. To conceptually integrate epigenetics and evo-devo into evolutionary theory, advocates of an Extended Evolutionary Synthesis (EES) argue that the MS's reductive gene-centrism should be abandoned in favor of a more inclusive organism-centered approach. To push the debate to a new level of understanding, we introduce the evolutionary biology of 'intra-genomic conflict' (IGC) to the controversy. This strategy is based on a twofold rationale. First, the field of IGC is both ‘gene-centered’ and 'intra-organismic' and, as such, coul...
Epigenetic Inheritance and Its Role in Evolutionary Biology: Re-Evaluation and New Perspectives
Biology, 2016
Epigenetics increasingly occupies a pivotal position in our understanding of inheritance, natural selection and, perhaps, even evolution. A survey of the PubMed database, however, reveals that the great majority (>93%) of epigenetic papers have an intra-, rather than an inter-generational focus, primarily on mechanisms and disease. Approximately~1% of epigenetic papers even mention the nexus of epigenetics, natural selection and evolution. Yet, when environments are dynamic (e.g., climate change effects), there may be an "epigenetic advantage" to phenotypic switching by epigenetic inheritance, rather than by gene mutation. An epigenetically-inherited trait can arise simultaneously in many individuals, as opposed to a single individual with a gene mutation. Moreover, a transient epigenetically-modified phenotype can be quickly "sunsetted", with individuals reverting to the original phenotype. Thus, epigenetic phenotype switching is dynamic and temporary and can help bridge periods of environmental stress. Epigenetic inheritance likely contributes to evolution both directly and indirectly. While there is as yet incomplete evidence of direct permanent incorporation of a complex epigenetic phenotype into the genome, doubtlessly, the presence of epigenetic markers and the phenotypes they create (which may sort quite separately from the genotype within a population) will influence natural selection and, so, drive the collective genotype of a population.
Evolutionary significance of epigenetic variation
Several chapters in this volume demonstrate how epigenetic work at the molecular level over the last few decades has revolutionized our understanding of genome function and developmental biology. However, epigenetic processes not only further our understanding of variation and regulation at the genomic and cellular levels, they also challenge our understanding of heritable phenotypic variation at the level of whole organisms and even the process of evolution by natural selection. Although many of the epigenetic mechanisms involved in differential gene expression are reset each generation, some epigenetic marks are faithfully transmitted across generations. In addition, we now know that natural variation exists not only at the DNA sequence level but also the epigenetic level. This may be particularly common in plants, and several studies suggest that epigenetic variation alone can cause significant heritable variation in phenotypic traits. Because of these observations, there is currently increasing interest in understanding the role of epigenetic processes in ecology and evolution.
Epigenetic Inheritance and Evolution
1995
We discuss the role of cell memory in heredity and evolution. We describe the properties of the epigenetic inheritance systems (EISs) that underlie cell memory and enable environmentally and developmentally induced cell phenotypes to be transmitted in cell lineages, and argue that transgenerational epigenetic inheritance is an important and neglected part of heredity. By looking at the part EISs have played in the evolution of multicellularity, ontogeny, chromosome organization, and the origin of some post-mating isolating mechanisms, we show how considering the role of epigenetic inheritance can sometimes shed light on major evolutionary processes.