The research project 'Epigenetic variation in seagrass clones: key to success without genetic variation?' was funded for three years by the Norwegian Research council, starting in spring 2015.
Seagrasses are flowering plants that grow in shallow coastal waters all around the world from tropical to subartic regions and rival tropical rainforests and coral reefs in economic value and in the ecosystem services they provide to humans. That seagrasses form meadows under water may explain why many people are not aware of their ecological and economic value, rivaling tropical rainforests and coral reefs in the ecosystems they provide to humans. All over the world, seagrass meadows are increasingly threatened by human impacts, including coastal erosion, over-fertilization, and global warming.
This work focuses on Zostera marina, also called eelgrass, the dominant seagrass in the Northern Hemisphere. Eelgrass grows new shoots along rhizomes running below the soil, just as strawberry plants grow new shoots along stolons. Thus, one or a few plants can grow an entire meadow; a big clone. A kilometre wide meadow can be a single clone, more than 1000 yrs old, and of exceptionally low genetic variation.
This is a paradox to evolutionary theory according to which only populations of high genetic variation will be able to adapt and survive perpetual environmental change. We suspect that the key to this paradox is a hidden layer of evolutionary relevant variation - called epigenetic variation.
Plants that are genetically identical, which means that they all share the same DNA sequence, can differ in DNA methylation, a common chemical modification that does not alter the DNA sequence but affects gene expression and, thus, the plants' characteristics.
The recent explosion of epigenetics in the scientific literature has focused primarily on medical implications and links to human health, virtually ignoring the evolutionary and ecological value of epigenetic variation in ecologically important non-model organisms. Our work aims to answer fundamental questions in the budding field of ecological epigenetics. If epigenetic variation is key for evolutionary success without genetic variation, plants may be able to adapt faster to environmental changes than we expect.
Zostera marina is an ideal model system for ecological epigenetics, given its ecological importance as key foundation species, and its partially clonal reproduction which eliminates the confounding effect of genetic variation.
The central aim of this proposal is to understand the role of epigenetic variation in the phenotypic plasticity of Zostera marina, a partially clonal marine plant with an ecological key role, thus filling fundamental knowledge gaps in the role of epigenetic versus genetic diversity as drivers of ecosystem resilience.
We focus on DNA methylation, the best studied mechanism in the context of heritable epigenetic variation. More specifically, we aim to: