Chap14

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Table 13.1: Types of Species Interactions
- Definitions based on the net impact on each species or individual involved:
  - Competition: Both species negatively impacted
    - Example: A lion and a hyena fighting over a carcass; both expend energy and risk injury.
  - Mutualism: Both species positively impacted
    - Example: A penstemon and the bee that pollinates it; the penstemon spreads its genes while the bee gets food.
  - Predation/Parasitism: Species 1 is positively impacted while species 2 is negatively impacted
    - Example: A fungus growing on a wild rosebush causes disease to the rose while benefiting the fungus.
  - Herbivory: Involves consumption of plants, generally not resulting in death but negatively impacting the plant.
  - Commensalism: Species 1 positively impacted, species 2 not impacted
    - Example: An orchid growing on a tree has a support structure, benefiting by being more accessible to pollinators, without impacting the tree.
  - Amensalism: Species 1 negatively impacted, species 2 not impacted
    - Example: A sunflower growing in the shade of a walnut tree.
  - Neutralism: Neither species positively or negatively impacted
    - Example: Two species of insects living on the same plant using different parts without affecting each other.

Predation: An organism kills another organism and consumes it.
Herbivory: An animal feeds on some portion of a plant but does not usually kill it.
Parasitism: An organism lives on or in a host, usually reducing the host’s fitness, sometimes killing it but usually not.
Parasitoid: A special case of predation where insect larvae live as parasites and eventually consume their host.
Pathogen: An organism inducing disease and reducing the fitness of hosts, may or may not kill the hosts.
- Example: Borrelia burgdorferii (causes Lyme disease).

Discusses the classic ecological scenario of the Snowshoe Hare and Lynx predation cycles, highlighting:
- Earlier hypotheses including sunspots and solar radiation cycles as causes of energy cycles.
- The impact of disease and food loss following overpopulation.
- Ongoing research emphasizing the complexity of predator-prey interactions, notably studies by Charles Krebs et al.

Key Variables:
- Prey (H) = Host
- p = Predation Rate
- $ext{Predation Rate (p) = Prey killed per unit of time}$
Impact: Depends on both host and predator populations, with predator growth influenced by prey availability (c).
Approximate one cycle in predator-prey relationship dynamics.

Refuges: Addition of spatial complexity enhances predator-prey oscillations, but does not fully solve challenges in simple systems under laboratory conditions.
Example by Gause: Paramecium aurelia and protozoan predator Didinium nasutum.
- Oscillations maintained with periodic immigration; influenced by real-world complexities (e.g., metapopulations on heterogeneous landscapes).

Investigated herbivorous and predatory mite dynamics utilizing habitat patches.
Results showed more intricate spatial arrangements produce viable predator-prey oscillations.
- Acknowledges the ecological variability over time and space, marking it as a foundational exploration in landscape ecology.

Emphasizes variability in the capture/consumption rate (p) across spatially structured populations.
Explains how environmental gradients influence predation dynamics, including different habitat types.

Case Study: Isle Royale National Park in Lake Superior illustrates:
- Low predation leads to high herbivory,
- Conversely, high predation leads to low herbivory, influencing balsam fir growth suppression and release dynamics.
Explains the lag effects observed (1-2 years behind moose variations).

Discuss how predation influences herbivory behavior, showcasing real-world examples, notably:
- Yellowstone National Park reintroduction of wolves influencing elk foraging behavior, revealing "The ecology of fear."

Behavioral Alteration: For example, certain parasitic worms in starlings change host behavior, enhancing parasite propagation.
- Discuss the work by Kathleen McAuliffe ("This Is Your Brain on Parasites") discussing manipulative effects of parasites on host behavior and broader socio-historical implications.
- Example of toxoplasmosis affecting rodent fear response to cats.

Integrative Concepts: Life histories, dispersal, and population ecology link with diversities in host presence and land use change.

Key Species:
- American Dog Tick (Dermacentor variabilis) linked with:
  - Rocky Mountain Spotted Fever (Rickettsia rickettsii)
  - Tularemia
- Blacklegged Tick (Ixodes scapularis) as a vector for:
  - Lyme Disease
  - Powassan virus
  - Anaplasmosis
  - Babesiosis (parasite)
  - Related to habitat use, niche breadth, and overlap.

Ticks require 2-3 blood meals before maturity, spending a significant portion of their life cycle off hosts. Host species can influence tick dispersal patterns.

Categories: Short distance vs. Long distance dispersal, highlighting that despite dispersal, population establishment and growth post-dispersal may not be assured.

Case study of Blacklegged Tick distribution emphasizing habitat composition and land use changes over time.
- Identifying dispersal paths and future land use impacts on tick distribution and associated disease risks.

Evaluation of potential tick populations via habitat composition, configuration, and climatic factors impacts on tick establishment and human health risks.

Prediction maps depict potential tick occurrences, hypothesis testing for field sampling, emphasizing the ecological implications regarding Lyme disease.
Emphasizes the complexity of relationships linking land use, host species presence, tick dynamics, and human health outcomes.