Epigenetics

chlamybubbles

(Ilkka)

How does non-genetic change affect evolutionary responses? Can short-term epigenetic responses tell us anything about the genetic changes that are likely to occur during evolution? 

What is the role of epigenetics in evolutionary adaptation?

First of all, what is epigenetics? In modern terms epigenetics can be defined as changes in gene transcription through modulation of chromatin, which are not brought about by changes in DNA sequence. These changes can be chemical modification of DNA by methylation or its associated histone proteins by different modifications. These changes can be inherited to daughter cells and sometimes even across generations.

We now know that epigenetic mechanisms are behind many phenomena, such as parental imprinting and regulation of gene expression based some environmental cues. It seems that some epigenetic phenomena can function as a cellular memory within individuals life time. It has been also claimed that sometimes epigenetic changes can be inherited across generations and while some of these examples are somewhat controversial it is now clear that this can happen. However, the extent of epigenetic inheritance is poorly understood at the moment.

It has been claimed that the existence epigenetic phenomena is of great importance to evolutionary theory. There are different ways in which we can imagine epigenetic effects to influence evolutionary outcomes. First, we could think that there are two different mutation systems present, the genetic and the epigenetic system. Presumably these systems have different properties and this could influence the rate and outcome of adaptation. Other way of thinking about epigenetics is that  this system is closely related to phenotypic plasticity and epigenetics could in theory allow the inheritance of acquired gene expression states that are induced by the environment. However, empirical understanding lacks far behind as to what, if any, implications epigenetics has for evolution.

In this project we investigating the questions: How does non-genetic change affect evolutionary responses? Can short-term epigenetic responses tell us anything about the genetic changes that are likely to occur during evolution? We are addressing these questions using both theoretical and empirical approaches.

We make theoretical models where we incorporate epigenetics to understand how epigenetics influences adaptation. Models are also important to generate predictions that we can test empirically. For empirical tests we use the single celled algae Chlamydomonas reinhardtii. We are running experiments to see how changing to epigenetic capabilities of the algae influences its ability to adapt to novel environments.

Publications from the project:

  • Filipposes paper in PloS One