Ph.D. Dissertation

		Shefferson, R.P. 2004.Evolutionary ecology of rare geophytes: dormancy and
		mycorrhizae in Cypripedium species. Ph.D. dissertation, University of California at Berkeley, Berkeley, California. 199p.

Abstract Orchids begin life consuming carbon provided by their mycorrhizal fungi. It is
thought that when they become photosynthetic adults, orchids lose their need for
fungal carbon. However, lady's slipper orchids (genus Cypripedium) can spend years
without sprouting and photosynthesizing, suggesting a potential lifelong need for
mycorrhizal carbon. This condition, called 'adult dormancy', suggests parallels to
nonphotosynthetic plants, which acquire all of their carbon from mycorrhizal fungi.
Here, I explored the links between adult dormancy and potential mycotrophy in genus
Cypripedium by: 1) documenting dormancy across multiple Cypripedium species; 2)
exploring the life history context of sprouting; 3) attempting to induce dormancy
experimentally; 4) identifying the primary fungi mycorrhizal with genus Cypripedium;
and 5) exploring mycorrhizal specialization in this group. In a ten-year census of
populations of C. candidum, C. parviflorum, and C. × andrewsii sympatric in a wet
meadow in Lake Co., Illinois, USA, I documented parallel trends in adult dormancy
among all populations. Dormancy durations up to six years were observed, and
dormancy occurred at a cost to annual survival of ten to twenty percent. Reproductive
trade-offs were most easily observed in smaller adults of all species. In an
experimental study of defoliation and shading on populations of C. calceolus and
Cephalanthera longifolia in Estonia, adult dormancy was not induced, but treated
plants experienced decreases in sprout quality suggesting scramble competition
among ramets. PCR amplification and sequencing of key genomic loci from
mycorrhizally colonized orchid tissue revealed that Cypripedium species as a whole
form mycorrhizal associations primarily with members of the fungal family
Tulasnellaceae, although some also associate with family Sebacinaceae.
Cypripedium species associating with both fungal families associated with a narrower
phylogenetic breadth of tulasnelloid fungi than those associating with only tulasnelloid
fungi, as were Cypripedium populations associating with fewer families relative to
populations with more families. Regional variation in mycorrhizal association
suggested a geographic mosaic of coevolving mycorrhizal associations. Cypripedium
species may be specialized on fungi that best provide carbon during their early years
or during dormancy. Conversely, they may be specialized on fungi that best provide
nitrogen or phosphorus.

Dissertation copyright notice: © 2004 by Richard P. Shefferson

Ph.D. Dissertation