Systematics Section / ASPT
Uyeda, Josef , Gross, Briana , Kephart, Susan .
Species Boundaries and Hybridization in Sympatric Species of Western Camassia (Agavaceae).
THE genus Camassia Lindl. (Agavaceae) is remarkable for its historic importance to western indigenous populations and dominance in wetland prairies, yet the six North American species have been little studied despite high morphological and geographic variation. Considerable potential for hybridization exists where the ranges of great camas (Camassia leichtlinii) and common camas (C. quamash) overlap in the Pacific Northwest. We used multivariate morphological and allozyme analyses and hand pollination to investigate species boundaries and putative hybrid zones at multiple sites extending from Oregon to British Columbia. Camassia quamash and C. leichtlinii differed significantly for bulb size, plant height, leaf width, number of flowers per inflorescence, corolla diameter, tepal length and width, and days to flowering in all years that traits were measured. Putative hybrids resembled C. quamash in flower number per inflorescence and sepal width, but were similar to C. leichtlinii in flowering time. Genotypes inferred from 12 resolvable loci across three buffer systems gave higher mean Neiís genetic identity (I) in intraspecific (0.90) versus interspecific (0.76) comparisons, with four alleles unique to either C. leichtlinii or C. quamash and five additional alleles common in one species but rare in the other. Sympatric populations also varied in the apparent extent of gene flow and genetic identity. Fruit set after hand pollination did not differ significantly with pollination type but interspecific crosses yielded significantly smaller capsule size, fewer seeds, and lower mean seed weight than intraspecific crosses. Less than 10 % of hybrid seeds germinated, significantly fewer than for open-pollinated controls (P < 0.000). Principle Component Analysis (PCA), hybrid indices, and crossing data all support species-level distinction of C. quamash and C. leichtlinii and further suggest that hybridization may contribute important variability in natural populations.
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1 - Willamette University, Department of Biology, 900 State Street, Salem, Oregon, 97301, USA
2 - Indiana University, Department of Biology, Jordan Hall, 1001 East Third Street, Bloomington, Indiana, 47405, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM