Causes and consequences of competitor diversity in food webs.

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題名:
Causes and consequences of competitor diversity in food webs.
著者: Jerome J. Weis
Yale University.
主題: Ecology
所屬期刊: Dissertation Abstracts International 75-09B(E).
描述: The production of biomass is understood as a reciprocal relationship between resources and consumers where (i) consumer species richness and biomass are driven directly by variation in the availability of resources and (ii) competitor species richness results in variation in resource competition and resource use that directly influences competitor biomass. Here I ask how competitor richness influences competitor biomass in ecosystems where there are 'top-down' consumptive effects on those competitor communities.
Predation has important cascading impacts on primary producer biomass and community composition in many ecosystems. In coastal New England lakes, both the presence and life history form of the zooplanktivorous fish alewife (Alosa pseudoharengus) have strong influence on the biomass, size structure and community composition of crustacean zooplankton communities. I show that alewife life history led to small but statistically significant differences in phytoplankton community composition among treatments. This compositional difference was driven primarily by an increase in the density of two edible phytoplankton genera associated with lower zooplankton biomass in the anadromous alewife treatment.
I use a three-trophic level consumer-resource model to ask how differential responses to predation influence consumer diversity effects at two scales; (i) in patches with and without predator populations, and (ii) at a 'regional' scale, consisting of one patch with- and one patch without a predator population. At the local scale, the strength and direction of consumer diversity effects depended on the strength of the differential response to predation. At the regional scale, I observed transgressive overyielding driven by a positive complementarity effect for parameters that define a strong differential response to predation.
I ask if there is a positive correlation between plankton competitor richness and competitor biomass in a landscape of lakes where variation in predation by a zooplanktivorous fish, alewife (Alosa pseudoharengus ) impacts the richness and biomass of lower trophic levels. I use data from two data sets designed to measure plankton community responses to alewife presence and life history; a whole-lake survey of 12-lakes and a pelagic mesocosm experiment. In the mesocosm experiment, I observed a significant positive relationship between zooplankton species richness and biomass associated with alewife presence and life history. A weaker positive relationship between phytoplankton genus richness and biomass was associated with variation in total phosphorus over time. In the 12-lake survey, zooplankton biomass was driven by spatial and temporal variation in alewife presence, but not correlated with zooplankton species richness.
In a microcosm experiment ask how the species richness of an assemblage of five species of freshwater phytoplankton influences phytoplankton biomass in the presence and absence of a population of the zooplankton herbivore Daphnia pulicaria. In the absence of Daphnia, species rich phytoplankton communities yielded more biomass than average monoculture phytoplankter populations at two time periods. This overyielding was driven primarily by a selection effect driven by a fast growing diatom species early in the experiment, and a high yielding Chlorophycean green species late. In the presence of Daphnia, the same two species dominated phytoplankton polycultures, but polyculture biomass was never greater than average monoculture biomass.
出版者: Thesis (Ph.D.)--Yale University, 2014.
建立日期: 2014
格式: 166 p..
語言: 英文
識別號: ISBN9781321063608
資源來源: NUTN ALEPH

連結

Causes and consequences of competitor diversity in food webs.

Jerome J. Weis Yale University. 2014

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