Epigenetics continues to fascinate, especially the notion that it blurs the line between “nature and nurture” and could make Lamarckian adaptation via the inheritance of acquired characteristics possible. That this is in principle possible is clear: in the model plant Arabidopsis thaliana (Thale cress), experimentally induced DNA methylation variation can be inherited and affect important traits. The question is whether this is important in nature. Recent studies of A. thaliana have revealed a pattern of correlation between levels of methylation and climate variables that strongly suggests that methylation is important in adaptation. However, somewhat paradoxically, the experiments also showed that much of the variation for this epigenetic trait appears to have a genetic rather than an epigenetic basis. This suggest that epigenetics may indeed be important for adaptation, but as part of a genetic mechanism that is currently not understood. The goal of this project was to determine whether the global pattern of methylation has a genetic or an epigenetic basis, and to use this information to elucidate the ultimate basis for the global pattern of variation: natural selection.
The main conclusion of the project was that the pattern of epigenetic variation is impossible to understand without understanding transposable element variation, which in turn is impossible to understand without independently sequencing and aligning population samples of genomes. Hence much of the effort of the project was devoted to this, a major undertaking. Experiments to answer the mechanisms of inheritance are only now being analyzed with this in mind.
