Shefferson 2009

		Shefferson, R.P. 2009. The evolutionary ecology of vegetative dormancy in
		mature herbaceous perennials. Journal of Ecology 97:1000-1009.

Summary
1. I present an evolutionary ecology interpretation of vegetative dormancy in mature
herbaceous perennials. This kind of vegetative dormancy has been noted for at least
40 years, but has only recently become a topic of study.
2. Vegetative dormancy may be considered in a life-history context. Both vegetative
dormancy and mortality typically decrease with increasing size. Vegetative dormancy’s
relationship to reproduction is more complex, because some species increase
flowering and fruiting after dormancy while others do the opposite.
3. If vegetative dormancy is adaptive, then it is most likely a bet-hedging trait.
Dormancy-prone plants are often long-lived, and in such organisms, bet-hedging
traits should counter the effects of environmental stochasticity on adult survival. This
adaptive context may vary by life span, because in shorter-lived plants, fitness is most
sensitive to changes in reproduction rather than survival.
4. Vegetative dormancy could evolve if the costs of sprouting ever outweigh the
benefits. The benefits of sprouting include: (i) photosynthesis and (ii) the opportunity
to flower and reproduce. The costs include: (i) greater chance of herbivory, (ii) greater
need for limiting nutrients, and (iii) greater maintenance costs. The many losses of
photosynthesis among plants suggest that these benefits may not always outweigh
the costs.
5. Vegetative dormancy may be an evolutionary step towards the loss of
photosynthesis. Many non-photosynthetic plants acquire carbon from their mycorrhizal
fungi. Many autotrophic, dormancy-prone plants also acquire some carbon from their
mycorrhizal fungi. Further, nonphotosynthetic plants often become dormant to an even
greater extent than autotrophic, dormancy-prone plants.
6. Synthesis. Vegetative dormancy often occurs in clades with non-photosynthetic,
myco-heterotrophic plants, with implications for the evolution of traits involved in
carbon nutrition. The links between vegetative dormancy, other life-history traits,
mycorrhizas and the loss of photosynthesis should provide exciting directions for
further research in plant evolutionary ecology. Particularly needed is an assessment
of the physiology of vegetative dormancy, including whether the mycorrhiza is a carbon
source in all dormancy-prone plant species. Equally important is a better
understanding of the genetic relationships among photosynthesis, myco-heterotrophy
and dormancy.

Shefferson 2009