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Genetics Section

Cronn, RC [1], Horning, Matthew [1], Huot, Rebecca [2].

Genetic diversity in hexaploid Calamagrostis breweri (Poaceae), a narrow alpine endemic.

Shorthair reedgrass (Calamagrostis breweri Thurber) is a delicate caespitose grass known from limited alpine locations in Oregon (Mt. Hood, Mt. Jefferson) and California (Salmon, Klamath, and Trinity Ranges; Sierra Nevada Range). Because of the rarity of this species in Oregon (State Heritage rank of S2, “potentially imperiled”), genetic studies of the Mt. Hood and Mt. Jefferson populations have been initiated to characterize the distinctiveness of these populations to each other and to C. breweri from California. Genetic variation in 200 tillers from four locations (Mt. Hood, OR; Mt. Jefferson, OR; Mt. Eddy, CA; Tioga Pass, CA) was evaluated by screening chloroplast DNA haplotype variation and nuclear Amplified Fragment Length Polymorphism (AFLP) variation. Analysis of chloroplast DNA showed complete differentiation between the Tioga population and more northerly populations, as well as a dramatic reduction in haplotypes (five at Tioga, o­ne in northern populations). This genetic discontinuity correlates with chromosomal differences between these entities, and it provides additional support for recognizing southern (e.g., Tioga; 2n = 28) and northern (2n = 42) C. breweri as separate species. Populations from Oregon show far less nuclear AFLP variation than either Californian population. Within Oregon, plants from Mt. Hood exhibit almost twice the variation (65 variable bands; He = 0.151) as plants from Mt. Jefferson (36 variable markers; He = 0.094). Despite a low level of AFLP diversity, Hood and Jefferson populations show clear differences in the apportionment of genetic variation; estimates of subdivision based o­n variance in allele frequencies (fPT = 0.154; P = 0.001) are significant and largely attributed to three marker loci. Results from this study indicate that Hood and Jefferson populations may be sufficiently distinct to show patterns of local adaptation, an hypothesis that will be tested in planned common garden experiments

1 - USDA Forest Service, Forest Genetics, Pacific Nothwest Research Station, 3200 SW Jefferson Way, Corvallis, Oregon, 97331-4401, USA
2 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA

population genetic diversity
Calamagrostis breweri
chloroplast DNA

Presentation Type: Paper
Session: 41-14
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 11:30 AM
Abstract ID:722

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