Related Experiment Video
Updated: Jul 2, 2026
10:20
Linking Predation Risk, Herbivore Physiological Stress and Microbial Decomposition of Plant Litter
Published on: March 12, 2013
Intraspecific variation in a predator affects community structure and cascading trophic interactions
David M Post1, Eric P Palkovacs, Erika G Schielke
1Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520-8106, USA. david.post@yale.edu
Ecology
|August 19, 2008
Summary
Intraspecific variation in alewife (Alosa pseudoharengus) life history and foraging traits significantly alters zooplankton communities and trophic cascades. This predator variation impacts ecosystem processes by modifying predator-prey interactions.
Area of Science:
- Ecology
- Evolutionary Biology
- Freshwater Ecosystems
Background:
- Intraspecific phenotypic variation is common but its ecosystem-level effects are unclear.
- Predator variation can influence community structure and trophic interactions.
- Alewives (Alosa pseudoharengus) exhibit life history and foraging variations.
Purpose of the Study:
- To investigate how intraspecific variation in alewives affects pelagic zooplankton community structure.
- To determine the impact of alewife life history (seasonal vs. year-round freshwater residence) and foraging morphology on trophic cascades.
- To understand the role of predator phenotypic diversity in regulating ecosystem processes.
Main Methods:
- Compared zooplankton community structure, algal biomass, and total phosphorus in lakes with landlocked, anadromous, or no alewives.
- Analyzed the effects of alewife freshwater residence duration and foraging morphology differences.
- Assessed changes in zooplankton body size and biomass based on alewife presence and type.
Main Results:
- Alewife presence and variation strongly influenced zooplankton community structure, with landlocked alewife lakes showing small zooplankton year-round, and no-alewife lakes showing large zooplankton year-round.
- Anadromous alewife lakes exhibited seasonal zooplankton size shifts.
- In summer, alewife foraging morphology affected zooplankton biomass and body size, and intraspecific variation altered trophic cascade strength.
Conclusions:
- Intraspecific phenotypic variation in predators like alewives significantly regulates zooplankton community structure.
- Predator variation modifies the strength and form of trophic cascades, impacting ecosystem processes.
- Understanding intraspecific diversity is crucial for predicting ecological and ecosystem responses.
Related Concept Videos
02:39Predator-Prey Interactions
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.Although predation is commonly associated with carnivory, for...
01:28Microbial Interactions: Predation
Microbial predation refers to the process by which one microorganism kills and consumes another to obtain nutrients and energy. It encompasses both bacterial and protozoan predators. This interaction plays a crucial role in shaping microbial communities and regulating nutrient cycling.Bacterial Predators: Epibiotic vs. EndobioticBacterial predators are classified based on their mode of attack as either epibiotic or endobiotic. Epibiotic predators, such as Vampirococcus, attach to the surface of...
02:34Competition
When organisms require the same limited resources within an environment, they may have to compete for them. Competition is a net-negative interaction. Even if two competing individuals or populations do not interact directly, the overall fitness of both competitors is lowered as a result of not having full access to the limited resource.Intraspecific competition, which occurs between individuals of the same species, serves as a natural mechanism for regulating population size. Too much...
00:58Symbiosis
Symbiotic relationships are long-term, close interactions between individuals of different species that affect the distribution and abundance of those species. When a relationship is beneficial to both species, this is called mutualism. When the relationship is beneficial to one species but neither beneficial nor harmful to the other species, this is called commensalism. When one organism is harmed to benefit another, the relationship is known as parasitism. These types of relationships often...
00:30What are Populations and Communities?
Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting populations of different species. Metapopulations span multiple populations of the same species that occupy different areas. Metapopulations interact through immigration and emigration, providing genetic diversity that lends resilience to harsh environments. Population size and density can be estimated using quadrat and mark and recapture...
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.Positive Frequency-Dependent SelectionIn positive...