Term Paper Prospectus
Jill Sutton
October 2, 1998.
Written Summary
Carnivorous plants have evolved
the ability to lure prey and utilize nutrients absorbed from captured prey
to fuel their metabolism. The unique ecological role of carnivorous
plant species provides opportunity for many interesting interactions including,
mutualism, competition and digestive symbioses (Givnish, 1989). The
purple pitcher plant (Sarracenia pupurea) has a modified leaf designed
to attract, capture and consume invertebrates and small vertebrates (Chapin
and Pastor, 1995). Bacterial symbionts and prey mutualists aid the
purple pitcher plant in the digestion and capture of various prey species;
allowing the extraction of environmentally limiting nutrients such as nitrogen,
phosphorus, sulfur and metals from digested prey (Hardwick and Giberson,
1996; Bradshaw and Creelman, 1984). The purple pitcher plant often resides
in acidic swamps, bogs and wet meadows (Heard, 1998). Pitcher plants
use nutrients absorbed from prey items to exploit areas that are low in
nutrient availability, discouraging competition with other non-carnivorous
plants (Chapin and Pastor, 1995).
The generalized structure of
a fully developed pitcher is a cylindrical open leaf, bounded by a hood
(Pietropaolo, 1986). The modified leaf shape collects water in a
cavity where captured animals drown and are digested by autolytic digestive
enzymes (Givnish, 1989). The accumulated water is not produced by
the plant itself making the pitcher dependent on the presence of rain or
moisture (Bradshaw and Creelman, 1984).
The pitcher consists of four
different sections that facilitate the attraction, capture and digestion
of prey (Pietropaolo, 1986). The first section, often called the
"attractive zone", is located on the underside of the hood (Newell and
Natase, 1998). The attractive zone is usually brightly colored and contains
sweet nectars to entice animals into the plant (Newell and Natase, 1998).
Downward sloping, stiff hairs, also located in the first section of the
pitcher, direct the movement of prey downward to the fluid below (Newell
and Natase, 1998). If this passive approach fails, a second section of
the pitcher offers numerous glands of nectar to entice the prey further
downward (Pietropaolo, 1986). When the prey contacts the second and
third zones they encounter a smooth, wax-like surface that breaks away
easily preventing escape (Newell and Natase, 1998). The fourth section,
the digestive and absorptive zone, also has downward pointing hairs to
prevent escape (Pietropaolo, 1986).
The fluid filled digestive and
absorptive section harbors a number of non-prey fauna including bacteria,
protozoans, rotifers and small crustaceans (Givnish, 1989). Unlike
most carnivorous species, the pitcher plant lacks digestive glands and
requires non-prey inhabitants to aid in the decomposition of prey
(Hardwick and Giberson (1996). The prey is digested and nutrients
are absorbed by the plant to increase photosynthesis and nectar production
and by the non-prey inhabitants to increase digestive enzyme synthesis
(Chapin and Pastor, 1995). Nutrient uptake has been reported to have
both positive and limiting effects on the plant growth of Sarracenia pupurea
(Cresswell, 1993).
The pitcher plant exhibits a
prey-mutualism relationship with a mosquito (Wyeomyia smithii) that uses
the pitcher fluid as a refuge for developing larvae (Lair et al., 1997).
Female mosquitos select pitcher plants by means of pitcher age, attractiveness,
and size (Natase e. al., 1995). She will usually deposit the eggs
into newly opened pitchers exhibiting attractive colors (Jaffe et al.,
1995). The larvae produced from the eggs will eventually make their
way to the fluid below and develop into adult mosquitos (Natase et al.,
1995). The pitcher benefits from this relationship by attracting
other prey items that feed on the mosquitos and their larvae (Givnish,
1989). The pitcher may also benefit from the recruitment of mosquitos
as potential pollinators (Givnish, 1989).
Annotated Bibliography
Bradshaw, W. E. and R. A. Creelman. 1984. Mutualism between
the carnivorous purple pitcher plant and its inhabitants.
The American Midland Naturalist. 112:294-304.
Examination of the roles of a mosquito and a midge in the quickening
of ammonia's presence in decomposition processes of the purple pitcher
plant. Evaluation of photosynthetic activity related to increased availability
of carbon dioxide through carnivorous processes. Good representation
of the effects of prey mutualism.
Chapin, C. T. and J. Pastor. 1995. Nutrient limitations
in the northern pitcher plant Sarracenia pupurea. Canadian
Journal of Botany. 73:728-734.
Biological overview of the purple pitcher plant and the habitats that
it exploits. Evaluation of the required nutrients, and their
ideal concentration levels. Review of the costs and benefits of carnivory
to the pitcher plant.
Cresswell, J. E. 1993. The morphological correlates of Prey
Capture and resource parasitism in pitchers of the carnivorous
plant Sarracenia pupurea. The American
Midland Naturalist. 129:35-41.
An evaluation of the variation of prey capture and the potential relationship
to pitcher plant morphology. Potential relationships examined
between spatial density and variation in prey capture, along with associated
frequency of occluded pitchers due to occupation of spiders. Viable
explanation considering spiders as "resource parasites" to the larger,
shorter pitcher plants. Interesting connection between pitcher plant
size and accumulated biomass.
Givnish, T.J. 1989. Ecology and evolution of carnivorous
plants. pp. 234-290 In : W.G Abrahamson (ed.) Plant
Animal
Interactions. McGraw-Hill, New York.
480 pp.
Excellent overview of ecological and evolutionary characteristics of
carnivorous plants. Examines plant-animal interactions as prey, predator,
and symbiotic mutalism. Describes the costs and benefits of carnivory
and relates other theories and models to nutrient budgets.
Hardwick, M.E. and D.J. Giberson. 1996. Aquatic insect populations
in transplanted and natural populations of the purple
pitcher plant, Sarracenia pupurea, on Prince
Edward Island. Canadian Journal of Zoology. 74
(11):1956-1963.
Review of the biological relationship of aquatic insect populations
within the pitcher of the purple pitcher plant. Discussion of potential
prey inhabitants and their mutual or prey relationships with the pitcher
plant. Interesting discussion of the variation between natural and
transplanted specimens.
Heard, S. B. 1998. Capture rates of invertebrate prey by
the pitcher plant Sarracenia Pupurea L. American
Midland
Naturalist. 139:79-89.
An examination of capture rates and how they related to species of
invertebrate prey of the pitcher plant. General overview of the biology
of the pitcher pant. Evaluation of the relationship exhibited between
insect and carnivorous plants. Interesting depiction of the spatial
distribution of pitcher plants.
Jaffe, K., M. S. Blum, H.M. Fales, R.T. Mason, and A. Cabera.
1995. On insect attractants from pitcher plants of the genus
Heliamphora, Sarraceniaceae). Journal
of Chemical Ecology. 21(3):379-384.
An analysis of the various chemicals that are utilized by pitcher plants
to attract prey. Comparisons of pitcher health, size and accumulated
prey biomass were examined . Interesting overview of the diversity
of chemicals used to attract prey.
Lair, K.P., W.E. Bradshaw, and C.M. Holzpfel. 1997. Evolutionary
divergence of the genetic architecture underlying photo
periodism in the pitcher plant mosquito. Genetics.
147:1873-1883.
An overview of general mosquito behavior and characteristics.
The evaluation of evolutionary divergence between populations of mosquitos.
General Biology of the immature and mature stages of the life cycle of
the mosquito, and how it relates to the pitcher plant life cycle.
Natase, A..J., C. De la Rosa, and S.J. Newell. 1995. Abundance
of pitcher-plant mosquitoes, Wyeomyia smithii (Coq.)
(Diptera: Cuicidae) and midges, Meriocnemus knabi
Coq (Diptera: Chironomidae), in relation to pitcher characteristics of
Sarracenia pupurea. American Midland Naturalist.
133: 44-51.
An overview of the mosquito and midge development of larvae within
the fluid filled section of the pitcher plant. Potential factors
examined include microclimate, pitcher health, and fluid abundance.
Interesting evaluation of pitcher communities and associated relationship
with larval invertebrates.
Newell, S. J., and A. J. Natase. 1998. Efficiency of insect
capture by Sarracenia pupurea (Sarraceniaceae) the northern
pitcher plant. American Journal of
Botany 85(1):88-91.
A review of insect attraction techniques of the pitcher plant emphasizing
the efficiency of capture in the fluid filled traps. Evaluation of
the costs and benefits of carnivory to the pitcher plant were discussed
at a superficial level. The "natural efficiency" theory presented
seems to apply to the capture rates presented. Good application for
general overview.
Pietropaolo, J., and P. Pietropaolo. 1986. Carnivorous
plants of the world. Timber Press Inc. Portland, Oregon.
206 pp.
An organized book outlining specific characteristics of various carnivorous
plants including the pitcher plant. General discussion of carnivorous
plant habitat, biology, trapping techniques, potential inhabitants, and
sexual reproduction. Interesting display of propagation and cultivation
techniques.