Fact sheet 9: Epigenetics at the community level

Bárbara Díez Rodríguez

The emerging field of community and ecosystem genetics has shown that genetic diversity, defined as any measure that quantifies the magnitude of genetic variability within a population, has a strong impact on populations, communities and ecosystems both at the same and at different trophic levels. [1, 2] For instance, it has been shown that higher genetic diversity has a positive correlation on species diversity in a given grassland community [3]. Genetic diversity of the host plant can influence arthropod communities. For example, susceptibility to certain herbivores was shown to be influenced by host genotype in poplar [4]. A study by Johnson et al. [5] showed that the number of plant genotypes affected the arthropod community found on Oenethera biennis, translating into positive effects on total arthropod species richness, and in a study by Robinson et al. [6] genetic variation in functional traits was found to affect arthropod community composition in aspen trees (P. tremulae). However, there are also reports, where the host genotype does not show any influence on associated arthropod communities, e.g. in oak [7]. Genetic diversity of dominant plant species can also affect nutrient flux. For example, genotypic variation in aspen can have a strong effect on some processes, like litter decomposition [8]. Generally speaking, intraspecific trait variability contributes to amplify the functional diversity of plant communities, a key component of biodiversity with important implications for species coexistence and ecosystem functioning [9]. Until not so long ago, the underlying DNA sequence was thought to be the main source of biodiversity and to provide the baseline for evolution by natural selection and genetic diversity [10], but more recent studies show that heritable epigenetic variation can have adaptive effects on populations [11], has a bigger role in plasticity than previously thought, and that genetic mutations are not the only source of phenotypic variation [12, 13]. For instance, it has been shown that epigenetic mechanisms have a role in allelopathy and that epigenetic changes might be more determinant than genetic variability in the success of plant invasions [14, 15]. Also, epigenetic variation has a role on how plants respond to environmental stress conditions [16]. Therefore, an epigenomics approach to study ecosystem and community processes becomes especially important because these processes represent the combined effects of interactions among multiple species, environmental variation and complex feedback mechanisms that can be difficult to understand in an evolutionary context.

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