The Role of Epigenetic Modifications in Evolution: Understanding How Environmental Factors Shape Heritable Gene Expression Across Generations

Epigenetic modifications provide a mechanism through which environmental factors can induce heritable changes in gene expression without altering the underlying DNA sequence. While the Modern Synthesis emphasises genetic mutation and natural selection as the primary drivers of evolution, growing evidence highlights the role of DNA methylation, histone modifications, and non-coding RNAs in enabling phenotypic plasticity and transgenerational inheritance. These mechanisms allow organisms to respond to environmental conditions more rapidly than genetic changes alone would permit, and in some cases, these responses are transmitted across generations via the germline. Empirical studies from both plant and animal systems demonstrate how exposures to stress, nutritional changes, and chemical disruptors can leave stable epigenetic marks. Additionally, large-scale genomic rearrangements such as chromoanagenesis point to the potential for abrupt structural variation to interact with epigenetic processes. Incorporating such findings within the framework of the Extended Evolutionary Synthesis expands traditional evolutionary models, offering a more integrated understanding of how environmental stimuli shape heritable variation and influence evolutionary trajectories over both short and long timescales.