MORRIS, JULIE A.* AND JOHN V. FREUDENSTEIN. 1Department of Biological Sciences, Kent State University, Kent OH 44242 2Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43212. - A systematic study of the North American Yellow Lady's Slipper orchids.
The North American Yellow Lady's Slipper Orchids (Cypripedium)
and their relatives present a large amount of variation that has
remained intractable to study of morphological characters alone. In
this study, the group was investigated using inter-simple sequence
repeat (ISSR) markers and morphometric analysis of floral structures.
Samples were collected from multiple populations of C.
parviflorum and C. pubescens from across their ranges, as
well as from populations of C. kentuckiense, C. candidum
and C. montanum. One population of C. californicum was
included as an outgroup. Individuals were scored for the presence or
absence of bands for 8 ISSR primers, and the data were analyzed
cladistically using parsimony, and phenetically using UPGMA and
neighbor-joining. Twenty-six floral characters were measured and
analyzed using principal component analysis; lip shape was quantified
using a truss approach. Populations of C. pubescens and C.
parviflorum are intermixed in all of the analyses with very few
patterns correlated with morphological differences. Some patterns
seem to relate to geographical distributions. This could mean either
that these morphologies have arisen independently multiple times, or
that they were perhaps largely distinct in the past, but continue to
exchange genes when in proximity. Populations of C.
kentuckiense fall out in two clades associated with two different
populations of C. pubescens. This could also be due to
convergent evolution or occurrences of secondary hybridization. In
each of these cases we favor the secondary gene flow hypothesis. The
distinctness of the white lady’s slippers, C. candidum and
C. montanum, from the rest of this clade is well supported.
Key words: Cypripedium, ISSR, morphometrics, Orchidaceae