PARENT SESSION
Oral Session #3: Conservation Ecology: Threatened and Endangered Species.
Presiding: J. Lawler
Monday, August 5. 8:00 AM to 11:30 AM. Graham Meeting Room, TCC.

The Real Deal? Seeking evidence of hybridization in the endangered Colorado endemic Physaria bellii (Bell's Twinpod).

Courter, L.^*,1, ¹ Colorado State University, Fort Collins, CO

ABSTRACT- Physaria bellii (Brassicaceae) is found on open shale and sandstone washes of the Niobrara and Pierre formations in Larimer, Boulder and Jefferson Counties in Colorado. It has been classified as "imperiled" (G2S2) by the Colorado Natural Heritage Program. Although populations are considered stable, P. bellii probably has never been common due to its particular habitat preferences. There is an approximately 30 mile gap in the north-south distribution of P. bellii. South of this gap, P. bellii has been anecdotally reported to hybridize with a more common congener, P. vitulifera. Results will be presented from a study using molecular markers to look for evidence that hybridization is occurring, since hybridization with more common congeners can threaten rare species. Amplified Fragment Length Polymorphisms (AFLPs) were used to generate species-specific markers. Data on the frequency of these markers in pure parental individuals and putative hybrids will be presented in addition to data on morphological characters that differ between species. Finally, results will be presented from a search for putative hybrids conducted north of the gap in this species' distribution. If hybrids are confined to the southern part of P. bellii's range, then the gap in P. bellii's distribution may serve as an effective barrier to introgression of P. vitulifera alleles into the main part of P. bellii's range.

KEY WORDS: hybridization, endemic, AFLPs, plants