I am studying threats to the endangered Colorado endemic plant, Physaria bellii, Bell’s Twinpod.  Physaria. bellii is found only in Larimer, Boulder and Jefferson counties in Colorado, on soils in the Niobrara and Pierre formations.  It is in the Brassicaceae, and is a self-incompatible perennial.  Although populations are currently thought to be stable, P. bellii still faces several threats including habitat fragmentation, competition with exotic invasives and hybridization with a more common congener, P. vitulifera.
       My study has two main components.  First, I will use molecular markers, such as AFLPs or microsatellites, to characterize the genetic structure of the approximately 20 populations.  Analysis of these markers can reveal evidence of phenomena such as inbreeding depression, outbreeding depression or genetic drift.  Inferences can then be made as to the relative health of each population.  Secondly, I will use morphology, pollination studies and molecular markers to assess the threat from hybridization with P. vitulifera.  The two species’ ranges overlap slightly and anecdotal evidence suggests the presence of hybrids.  The extent of the hybrid zone, fertility of the hybrids and whether P. bellii is threatened by hybridization will be determined.
        The results of this study will be made available to landowners and other interested parties.  This information should be valuable when decisions are made regarding future efforts to protect this species.

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