COLLABORATIVE RESERARCH: Symbiosis and Repercussions of Extreme Ecological Specificity

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The non-photosynthetic plant Pterospora andromedea relies on an obligate relationship with a fungus in the genus Rhizopogon to obtain carbon and energy. This fungus in turn relies on an obligate association with conifer trees to obtain its carbon and energy. Such complex tripartite symbioses have been little studied. However, under conditions of human disturbance or climate change, extreme dependence on highly specific associations within the relationships may lead to population decline. Indeed, populations of Pterospora are in steep decline in eastern North America, but appear to be secure in the west. The proposed research will investigate the historic association, co-migration and genetic structure in Pterospora/Rhizopogon pairs from across North America. The central hypothesis is that health and vigor of this relationship will be highest in the center of its geographic range (e.g. Pacific Northwest) and that populations that exist outside of this optimal center, including those that are disjunct or at range margins (New England), will exhibit lower relative abundance and higher genetic differentiation, possibly due to increased effects of genetic drift and reduced gene flow. This investigation will elucidate historic patterns and variation in ecological specificity in this complex plant-fungal symbiosis and determine factors that explain contemporary patterns of population genetic structure of symbionts at the community level.This is a collaborative project that involves the synergistic melding of complementary expertise between two research teams, one from a small, liberal arts college (Centre College) and the other at a research intensive University (U of Wyoming). This collaboration will support research training and mentoring of a postdoctoral scholar, and several graduate students. Further, this research will fundamentally enhance the liberal arts learning environment at a primarily rural undergraduate institution by providing a dynamic research opportunity to stimulate the scientific development of undergraduate students and a meaningful mentorship opportunity.