Worley, Anne C. , Ford, Bruce A. , Ghazvini, Habibollah , Sawich, Lauren .
Morphological and genetic evidence for hybridization between a rare and common lady’s-slipper orchid, Cypripedium candidum and C. parviflorum (Orchidaceae).
Extinction through hybridization can be a significant threat to endangered species. This threat is greatest when hybrids are vigorous and fertile, putting the rare parental species at risk of extinction due to genetic assimilation. We examined hybridization between the globally endangered small white lady’s slipper (Cypripedium candidum) and the common yellow lady’s slipper (C. parviflorum var. makasin and C. p. var. pubescens) in four Manitoban populations. We used 10 morphological characters and 1061 AFLP loci to characterize variation in 186 plants. Canonical correlation analysis showed an extremely high correspondence between morphological and molecular data sets (r = 0.97 for the first axis) indicating morphology was highly predictive of the underlying genetic structure of individuals. Separate multivariate analyses of morphological (PCA) and genetic (PCoA) data clearly distinguished the two parental species. The two varieties of C. parviflorum were morphologically divergent but had complete genetic overlap. Hybrids were intermediate, and Â± evenly distributed between the parental species. This symmetry suggested bi-directional backcrossing and the potential for introgression. However, limited overlap between hybrids and parents indicated that most C. candidum and C. parviflorum individuals were distinct, despite the presence of hybrids in all populations. Thus, genetic assimilation had not yet occurred in the populations we examined. Future studies will compare the extent and direction of hybridization in small and large C. candidum populations, and the degree to which the widespread C. parviflorum has incorporated genetic material from other Cypripedium species.
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1 - University of Manitoba, Biological Sciences, Winnipeg, Manitoba, R3T 2N2
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, July 29th, 2008
Time: 8:30 AM