Interspecific Interactions: Parasitism, Mutualism

Types of Interspecific Interactions

• Need to recognize different types, such as parasitism, predation, and mutualism
• Be able to place them on a matrix of +/- interactions

Mutualism

• Know the differences among trophic, habitat, and service mutualisms
• Understand how the costs and benefits involved with mutualisms affect their evolution and maintenance
• Understand the implications of cheating in mutualisms, especially with the yucca-yucca moth system

Parasitism

• Know what parasites and parasitoids are
• Be able to distinguish between the two
• Familiarize with parasite-host & parasitoid-host interactions
• Understand both the Red Queen Hypothesis and coevolution between parasites and hosts
• Understand how the costs and benefits of sexual reproduction relate to coevolution
• Familiarize with the New Zealand mudsnail case study

Herbivory

• Recognize basic types of herbivory-defense strategies
• Understand the population and community effects of herbivory in goldenrod-dominated oldfield communities
• Understand evolutionary anachronism

Predation

• Recognize basic predation strategies and animal defenses against it

Predator-Prey Dynamics

• Interpret each part of the original Lotka-Volterra predator-prey model
• Understand zero-growth isoclines mathematically and biologically

Competition

• Know the difference between a fundamental and realized niche
• Understand how to quantify them experimentally
• Understand the difference between interspecific and intraspecific competition
• Understand the difference between exploitative/resource (indirect) and interference (direct) competition
• Understand how to experimentally identify limiting resources
• Specifically testing competition between two similar species (e.g., Connell's barnacles)
• Understand limiting similarity, resource partitioning, character displacement, and the "ghost of competition past”

Lotka-Volterra Model

• Understand how spatial and temporal variation promote coexistence
• Understand “equilibrium" in relation to population growth and the difference between a stable and unstable equilibrium
• Interpret phase planes, including the meaning of zero-growth isoclines, unstable vs. stable equilibria
• Relate phase planes to plots of population trajectories over time
• Interpret each part of the Lotka-Volterra competition model
• Know the "competition coefficient", aij
• Understand the relationship between phase plots, model parameters, and ecological interpretations for the four qualitatively different outcomes
• Understand how intraspecific and interspecific competition affect coexistence of competitors versus competitive exclusion

Disturbances

• Understand disturbances and disturbance regimes
• Connect disturbance regime changes expected community structure changes
• State key predictions of the Intermediate Disturbance Hypothesis
• Understand how those predictions relate to life-history tradeoffs
• Distinguish among the three models of succession proposed by Connell and Slatyer
• Know the difference between primary and secondary succession

Food Webs

• Understand trophic cascades, behavioral cascades, top-down control, and bottom-up control
• Understand the exploitation ecosystem model (aka the 'Step Model')
• Know what an "ecosystem engineer” is
• How it relates to keystone and dominant species
• Understand the "3 Rs" of community stability: Resistance, Return time, Resilience
• Know what Alternative Stable States are
• Understand what features make communities more stable in the face of disturbance (especially variation in connectance and diversity)
• Understand Community Impact and Total Importance
• Be able to distinguish between keystone species and dominant species (recognize that keystone species do not have to be predators)
• Diagram the direct and indirect interactions among populations

Disease Ecology

• Understand how interactions between infected and susceptible individuals contributes to disease spread (i.e., new infections)