Meeting Abstract
Populations that are adapted to local conditions may lose fitness as climate changes. This phenomenon, called adaptive lag, is potentially significant for Arctic ecosystems where the climate is warming rapidly and locally adapted populations occupy large areas. Eriophorum vaginatum is a tussock-forming sedge that occupies more than 300 million km2 in northern Alaska, Canada, and Siberia, where it contributes up to 37% of primary productivity and forms the undulating structure of tussock tundra. A 31- year reciprocal transplant experiment with E. vaginatum in Alaska showed that mass/tiller and flowering exhibited local adaptation, whereas survival and the growth rates of tiller populations displayed adaptive lag. Analysis of population genomic data using ddRAD sequencing showed significant differentiation between populations of E. vaginatum north and south of the tree line. In a common garden, northern populations senesced earlier than southern populations. In a second experiment established in 2014, gross primary productivity of tussocks from warmer southern sites was more sensitive to transplanting than that of tussocks from northern sites, which suggests that ecotypic control of GPP may affect the response of ecosystem productivity to climate change. As the climate warms, gene flow from south to north is likely to be limited for this long-lived species, and the probability of evolutionary rescue is not great. Instead, the abundance of E. vaginatum may decline followed by its replacement by shrubs. Because of the important role of this species in the Arctic tundra ecosystem, patterns of primary productivity and nutrient cycling are also likely to change.
