Genetic Discrimination of Spiranthes cernua Species Complex in South Carolina
Lucy A. Dueck
Savannah
River Ecology Laboratory, Drawer E, Aiken, SC 29802 USA
E-mail: dueck@srel.edu
James A. Fowler
South
Carolina Native Plant Society, Greenville, SC 29605 USA
Cris S. Hagen and Travis C. Glenn
Savannah
River Ecology Laboratory, Drawer E, Aiken, SC 29802 USA
Abstract
The genus Spiranthes (subfamily Orchidoideae, tribe Cranichideae)
has long been taxonomically problematic, and the compilospecies S.
cernua especially is perplexing because of hybridization and polymorphism.
Several populations of fall-blooming Spiranthes located in upstate
South Carolina differ from S. cernua in some morphological features,
but the ranges of other candidates in the species complex are more distant
(S. ochroleuca—Northeast, S. odorata—Southeast
coastal plain). Samples for genetic analysis therefore were collected
from these populations and outgroup species to compare with standards
of several Spiranthes species. Segments of DNA from the three
plant genomes—nuclear, mitochondrial, and chloroplast—were
amplified by PCR, sequenced, and then used for phylogenetic reconstruction.
Results from the organelle genomes suggest that one of the two suspected
S. cernua deviants has more affinity with S. ochroleuca
and differs from the other populations, which grouped mainly with S.
cernua standards. The conservative nuclear segment shows few intra-generic
differences. This pilot survey verifies the southern range extent of some
genes of a Spiranthes species. The survey also provides tools
for a broader study of the molecular phylogeny of this genus in North
America, which will be needed to delimit populations and habitats for
future conservation efforts.
Keywords: Spiranthes cernua, orchid genetics, DNA sequencing, molecular systematics.
SREL
Reprint #2930
Dueck, L. A., J. A. Fowler, C. S. Hagen, and T. C. Glenn. 2005. Genetic Discrimination of Spiranthes cernua Species Complex in South Carolina. Selbyana 26(1,2): 145-154.
