Speaker
Description
Recent experiments have shown that spontaneous epigenetic variation exists. This means variation in heritable epigenetic changes that behave in a manner analogous to genetic variation. Currently this sort of variation is best understood for DNA methylation in plants. We know that spontaneous DNA methylation changes happen, and the rate of these changes is many orders of magnitude higher than for genetic mutations. Based on theoretical models the extent on how epigenetic variation changes evolutionary dynamics depends on the properties of epigenetic variation. Namely the rate of spontaneous epigenetic changes, their stability, and the distribution of their phenotypic effects. If both epigenetic and genetic variation are present, and they both can affect the phenotype, this leads to an evolutionary dynamic where adaptation proceeds first using epigenetic variation and subsequently the same phenotype is fixed using genetic mutations. The question remains does this happen in the real world. We studied this question experimentally using the single celled algae Chlamydomonas, and observed that manipulation of the epigenetic system affected adaptation. Moreover, we observed many DNA methylation changes, that could not be explained by cis-acting mutations. In summary, epigenetic changes have the potential to influence adaptation, but to determine their importance we need better estimates of their phenotypic effects.
