Demographic response to shading and defoliation in two woodland orchids

Shefferson, Richard P.; Kull, Tiiu; Tali, Kadri

doi:10.1007/bf02805264

Cited by 30 publications

(19 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Parallel patterns in vegetative dormancy among nearby populations of both orchids and mariposa lilies reinforce the notion that climatic factors may drive dormancy (Miller et al. 2004; Shefferson et al. 2006; but see Shefferson & Tali 2007).…”

Section: Vegetative Dormancy As Life‐history Adaptationsupporting

confidence: 59%

The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plants

Shefferson¹

2009

Journal of Ecology

Self Cite

125

View full text Add to dashboard Cite

Summary1. 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.

show abstract

Section: Vegetative Dormancy As Life‐history Adaptationsupporting

confidence: 59%

The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plants

Shefferson¹

2009

Journal of Ecology

Self Cite

125

View full text Add to dashboard Cite

show abstract

“…9) may reduce available resources in nondrying shoots. A shading experiment on MX Cephalanthera longifolia induced a reduction in flower number per shoot in the following years (Shefferson et al 2006), further supporting the notion that limiting C resources interferes with fitness in MX orchids. Curiously, fruiting did not enhance detectable increase in dormancy of our albino and green individuals, contrasting with fruiting costs reported for diverse autotrophic orchids (Primack and Stacy 1998, Jacquemyn et al 2010, Sletvold and Å gen 2011: Their ability to recover C from mycorrhizal fungi after fruiting may buffer the previous reproductive efforts.…”

Section: Albinos' Fitness Is Reduced As Compared With Green Individualsmentioning

confidence: 59%

Why do mixotrophic plants stay green? A comparison between green and achlorophyllous orchid individuals in situ

Roy

Gonneau

Rocheteau

et al. 2013

Ecological Monographs

123

View full text Add to dashboard Cite

Abstract. Some forest plants adapt to shade by mixotrophy, i.e., they obtain carbon both from photosynthesis and from their root mycorrhizal fungi. Fully achlorophyllous species using exclusively fungal carbon (the so-called mycoheterotrophic plants) have repeatedly evolved from such mixotrophic ancestors. However, adaptations for this evolutionary transition, and the reasons why it has happened a limited number of times, remain unknown. We investigated this using achlorophyllous variants (i.e., albinos) spontaneously occurring in Cephalanthera damasonium, a mixotrophic orchid. In two populations, we compared albinos with co-occurring green individuals in situ. We investigated vegetative traits, namely, shoot phenology, dormancy, CO 2 and H 2 O leaf exchange, mycorrhizal colonization, degree of mycoheterotrophy (using 13 C abundance as a proxy), and susceptibility to pathogens and herbivores. We monitored seed production (in natural or experimental crosses) and seed germination. Albinos displayed (1) more frequent shoot drying at fruiting, possibly due to stomatal dysfunctions, (2) lower basal metabolism, (3) increased sensitivity to pathogens and herbivores, (4) higher dormancy and maladapted sprouting, and, probably due to the previous differences, (5) fewer seeds, with lower germination capacity. Over the growing season, green shoots shifted from using fungal carbon to an increasingly efficient photosynthesis at time of fruiting, when fungal colonization reached its minimum. Conversely, the lack of photosynthesis in fruiting albinos may contribute to carbon limitation, and to the abovementioned trends. With a 10 3 3 fitness reduction, albinos failed a successful transition to mycoheterotrophy because some traits inherited from their green ancestors are maladaptive. Conversely, mycoheterotrophy requires at least degeneration of leaves and stomata, optimization of the temporal pattern of fungal colonization and shoot sprouting, and new defenses against pathogens and herbivores. Transition to mycoheterotrophy likely requires progressive, joint evolution of these traits, while a sudden loss of photosynthesis leads to unfit plants. We provide explanations for the evolutionary stability of mixotrophic nutrition and for the rarity of emergence of carbon sinks in mycorrhizal networks. More broadly, this may explain what prevents the emergence of fully heterotrophic taxa in the numerous other mixotrophic plant or algal lineages recently described.

show abstract

“…Large plants may, therefore, be able to capture enough resources to allow flowering to occur for several consecutive years, whereas small plants may fail to flower for several consecutive years. Flowering may thus be particularly costly in shaded environments (Shefferson et al 2006). In addition, shading may also affect flower production, either as a direct consequence of shading or through reductions in plant size.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, shading may also affect flower production, either as a direct consequence of shading or through reductions in plant size. For example, shading led to a significant decline in the number of flowers per ramet and a decrease in ramet height in the woodland orchids Cypripedium calceolus and Cephalanthera longifolia (Shefferson et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Size‐dependent flowering and costs of reproduction affect population dynamics in a tuberous perennial woodland orchid

2010

View full text Add to dashboard Cite

Summary1. In woodland herbs, the probability of flowering and costs associated with reproduction may strongly depend on environmental context (shade vs. light habitats) and on plant size. This may be particularly true for tuberous orchids that inhabit woodlands, as the amount of incoming radiation and total leaf area strongly determine photosynthetic capacity and hence the amount of carbohydrates that can be relocated to below-ground storage organs that form next year's rosette and flowering stalk. 2. To fully comprehend the impact of size-dependent reproduction on population dynamics under varying light conditions, life cycle models should therefore include plant size in a continuous manner. In this study, annual changes in plant size and demographic behaviour of the tuberous perennial orchid Orchis purpurea were monitored during seven consecutive years (2003)(2004)(2005)(2006)(2007)(2008)(2009)) in open and shaded woodland. Integral projection models (IPMs) and life table response experiments (LTRE) were used to investigate the extent to which variation in plant size affected the overall population dynamics of this species and to decompose differences in population growth rates between populations of open and shaded woodland into contributions from growth, survival and reproduction. 3. Both plants in shaded and light environments needed to be a certain size to initiate flowering, but this threshold size was almost three times as large in shaded environments as in light environments. Plants in open woodlands flowered more frequently over the years, showed less size regression after flowering and produced significantly more fruits than plants in shaded environments, resulting in significantly larger population growth rates. 4. Our life cycle models revealed that costs of reproduction, measured at the population-level, were small in the light environment, and more than buffered by the increase in survival of flowering plants compared to non-flowering plants. In the shade environment, however, the costs of reproduction were significant and made the difference between a stable (current) and a growing (without reproduction costs) population. 5. Synthesis. Light penetration to the soil is a key variable determining population dynamics of woodland orchids. Our analyses show that differences in vital rates related to size-dependent reproduction (flowering) and growth are essential drivers of changes in orchid population dynamics in different light environments. The combination of IPMs and LTREs thus proves to be very useful when studying the fitness consequences of size-and context-dependent phenomena like flowering strategies and costs of reproduction.

show abstract

Demographic response to shading and defoliation in two woodland orchids

Cited by 30 publications

References 36 publications

The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plants

The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plants

Why do mixotrophic plants stay green? A comparison between green and achlorophyllous orchid individuals in situ

Size‐dependent flowering and costs of reproduction affect population dynamics in a tuberous perennial woodland orchid

Contact Info

Product

Resources

About