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Effects of warming ...
Effects of warming and nutrient enrichment on feeding behavior, population stability and persistence of consumers and their resources
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- Uszko, Wojciech, 1985- (författare)
- Umeå universitet,Institutionen för ekologi, miljö och geovetenskap
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- Diehl, Sebastian, Professor (preses)
- Umeå universitet,Institutionen för ekologi, miljö och geovetenskap
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- Persson, Lennart, Professor (preses)
- Umeå universitet,Institutionen för ekologi, miljö och geovetenskap
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- Vasseur, David, Professor (opponent)
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
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(creator_code:org_t)
- ISBN 9789176015445
- Umeå : Umeå University, 2016
- Engelska 27 s.
- Relaterad länk:
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https://umu.diva-por... (primary) (Raw object)
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- Consumer-resource interactions are the basic building blocks of every food web. In spite of being a central research theme of longstanding interest in ecology, the mechanisms governing the stability and persistence of consumer-resource interactions are still not entirely understood. In particular, theoretical predictions on consumer-resource stability along gradients of temperature and nutrient enrichment diverge widely and are sometimes in conflict with empirical results. In this thesis I address these issues from the angle of the functional response, which describes a consumer’s feeding rate as a function of resource density. Specifically, I explore mechanistic, nutrient-based consumer-resource interaction models with respect to the influence of feeding behavior (the shape of the functional response), environmental temperature, nutrient enrichment, and resource quality on consumer-resource stability and persistence. In order to parameterize these models I performed extensive laboratory experiments with pairs of freshwater pelagic algae and grazers of the genus Daphnia, which are widespread, ecologically important model organisms.I found a sigmoidal type III functional response in every studied Daphnia-algae species pair. The exact form of its shape is described by an exponent b which is determined by fitting functional response models to the experimental data. A high value of b can stabilize consumer-resource systems under the otherwise destabilizing influence of nutrient enrichment, as predicted by a novel stability criterion relating b to the consumer’s prey handling time, food conversion efficiency and mortality. Estimated parameter values and, consequently, stability predictions are sensitive to the method of parameter estimation, and I propose a new estimation procedure that minimizes parameter uncertainty. Because many consumers’ feeding rates depend on temperature, warming is expected to strongly affect food web stability. In functional response experiments over a broad temperature gradient, I found that the attack rate coefficient and the maximum ingestion rate of Daphnia are hump-shaped functions of temperature. Moreover, the functional response exponent increases with warming towards stronger type III responses. Plugging these findings into a nutrient-based consumer-resource model, I found that predator persistence is a U-shaped function of temperature in nutrient enrichment-temperature space. Enrichment easily turns the system unstable when the consumer has a type II response, whereas a type III response opens up a large region of stability at intermediate, for the consumer optimal, temperatures. These findings reconcile seemingly conflicting results of earlier studies of temperature effects on consumer-resource dynamics, which can be mapped as special cases onto the enrichment-temperature space. I finally demonstrate the utility of three key model ingredients - temperature dependence of rate parameters, a mechanistic description of the dynamics of algal resources, and a type III functional response in Daphnia - by successfully implementing them in the description and explanation of phytoplankton-Daphnia dynamics in a mesocosm experiment exploring effects of warming on the spring succession of the plankton.
Ämnesord
- NATURVETENSKAP -- Biologi -- Ekologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Ecology (hsv//eng)
Nyckelord
- consumer-resource
- Daphnia
- functional response
- nutrient enrichment
- parameter estimation
- persistence
- plankton
- predator-prey
- stability
- temperature
- type II
- type III
- warming
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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