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Title:Effects of diversity on community assembly dynamics in newly formed pond communities
Author(s):Holmes-Singh, Christopher
Advisor(s):Cáceres, Carla E.
Department / Program:School of Integrative Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Fresh Water
Genetic Variation
Daphnia: Growth & Development
Community Assembly
Intraspecific Variation
Interspecific Variation
Freshwater Zooplankton
Colonization Dynamics
Community Dissimilarity
Spatial Structure
Priority Effect
Monopolization Hypothesis
Phenotypic Plasticity
Alternative Stable States
Local Factors
Regional Factors
Community Structure
Experimental Ponds
Abstract:Theory suggests that the initial level of genetic or species diversity in a new habitat will influence community assembly dynamics. Previous studies have shown that species diverse communities can buffer against invasion by heterospecifics. In addition, the monopolization hypothesis predicts that a genetically diverse population will be more likely to adapt to the local environment, monopolize resources, and buffer against invading competitors. This rapid evolution of a focal population can enhance priority effects thereby decreasing invasibility of later arriving colonists (termed evolution-mediated priority effects). Nevertheless, empirical investigations of these diversity effects, at both the genetic and species level remain rare, especially for animal systems. To test this theory, we conducted a field experiment in which initial stocking diversity (both intra- and interspecies) of freshwater zooplankton in newly constructed pools was manipulated in a 2x2 fully factorial design. Zooplankton communities and several abiotic variables were sampled every two weeks (from May to August) for 3 years. Estimates of overland dispersal were measured in the second year of study. We also conducted laboratory assays on ecologically relevant traits for our focal Daphnia pulex clones originally stocked in the field experiment to determine if performance in the field (ability to persist) was determined by genotype differences and/or phenotypic plasticity in the population growth rate parameter, r. Despite theoretical predictions, after 3 years we found no difference in taxonomic richness or diversity among stocking treatments. A total of 31 species were recorded in the metacommunity with an average cumulative taxonomic richness ranging from 6.1 to 7.6 species per pool. Dispersal of zooplankton taxa was rapid with 8 taxa dispersing in 7 days, but we found no difference in the number of dispersing propagules based on number of neighboring source pools. Pools in the same patch, delimited into landscape “hexagons”, had similar community composition and variation in community structure was explained by average pH and dissolved oxygen concentration. Populations of our focal species, Daphnia pulex, exhibited rapid evolutionary change after the second year of study. However, performance in the field was not explained by genotype differences in intrinsic rate of natural increase (r) measured in the laboratory assays on high food, but may be explained by varying levels of plasticity in r among clones. Our study demonstrates that despite theoretical predictions that genetic diversity of a focal population and initial species diversity should influence community assembly dynamics, they do not appear to have an effect on early successional community species richness and diversity, or population persistence of the focal species D. pulex. Local abiotic factors or differences in dispersal rates among taxa may have a larger influence on community assembly dynamics in freshwater zooplankton metacommunities.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Christopher J Holmes-Singh
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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