The Heat Is on: Epigenetics and Climate Change-Associated Competition

Overview

Permafrost, a layer of frozen soil under the Arctic surface, stores nutrients that are typically inaccessible to plants. As climate change warms the Arctic, the melting permafrost releases those nutrients to the active layer, altering the environment. Analyzing Arctic species’ cellular basis of adaptation is crucial to understanding how the ecosystem as a whole will respond to the rapidly changing climate. We quantified global DNA methylation to assess the epigenetic component of adaptation. Salix pulchra is a foundational vascular plant that serves nutritional and habitat needs for many Arctic communities. Scientists at Toolik Field Station, located in the North Slope of the Alaska, annually fertilize the LTER (Long Term Ecological Research) plots with nitrogen and phosphorus to simulate the melting permafrost’s release of nutrients. The ITEX OTC (International Tundra Experiment Open Top Containers) plots are designed to retain heat and thus mimic the Arctic’s projected temperature increases. Using Salix samples collected from these experimental plots, we characterized the molecular response to thawing permafrost. We collected three leaves of Salix pulchra from three individuals at each site (ITEX OTC's, LTER, and wild), and analyzed these samples for differential global DNA methylation. Results of the LTER analyses show that as nutrient load increases, Salix increases global DNA methylation. These results suggest that nutrients, presumably released by thawing permafrost, may provide a competitive edge to previously nutrient limited species. The community level effect of this competition may be that historically dominant species “hunker down,” turning down gene expression of housekeeping genes to conserve energy for stress response and survival. Data from the OTCs display a similar but dampened correlation; the global methylation of OTC Salix lies between that of wild and ITEX Salix. This result may be due to the differences between the experiments; whereas the ITEX plots are fertilized yearly, the OTC plots just have a container around them to retain heat. This less drastic change from the wild condition may cause the less drastic methylation level change in the OTC Salix. Our investigation provides preliminary evidence for epigenetic adaptation in species that are forced to undergo adaptation to a rapidly changing environment. In addition, this study offers novel insights that come from an approach that uses molecular tools to interrogate critical questions from experimental ecology.

Competition history

• AJAS 2019 Category not listed

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