Predator and Anti-Predator Behavior Notes

The Hare's Dilemma

The lecture explores the "hare's dilemma," which questions whether offspring that are less stressed, less active, and larger are better off than those that are more stressed, more active, and smaller.
The central question is which type of offspring is more likely to survive and reproduce.

Evolutionary arms races (p. 57-59)
Predator and prey tactics (p. 59-61, 61-63)
Taste aversion (p.64)
Predator fear and the HPA axis (p. 66-67)
The other sense of adaptation (p. 64-66)

The Life-Dinner Principle: This principle, proposed by Dawkins & Krebs in 1979, highlights the asymmetrical selection pressures in predator-prey relationships. The prey is running for its life, while the predator is only running for its dinner.
Generalists vs. Specialists: Evolutionary arms races can lead to the development of generalist or specialist strategies in both predators and prey.

Genetic Preference/Predisposition: Some prey selection may be genetically determined.
Individual Learning: Animals can learn to prefer certain types of prey through individual experiences.
Social Learning: Animals can learn prey preferences by observing and imitating others (e.g., wild pigs learning to eat what others eat).
Sampling New Items: Animals, like mice and rats, may sample new food items to determine their suitability.

Prey detection involves perception, cognition, and neuroanatomy.
The electromagnetic spectrum plays a crucial role in how predators detect prey, including:
- Radio waves
- Microwaves
- Infrared (IR)
- Visible light (700-400 nanometers)
- Ultraviolet (UV)
- X-rays
- Gamma rays
Sound Reception: Animals use sound to detect prey, including:
- Infrasound (below 20 Hz)
- Acoustic (20 Hz - 20 kHz)
- Ultrasound (above 20 kHz)

Jakob von Uexküll (1864-1944) introduced the concept of "Umwelt."
Umwelt: Defined as "the perceptual world in which an organism exists and acts as a subject."

Prey capture can be achieved through:
- Anatomical adaptations
- Tool-assisted methods
- Cooperative strategies

Primary Defenses: Tactics employed prior to an attack/detection.
- Crypsis (=Camouflage): Blending in with the environment.
- Mimicry: Imitating another organism to avoid detection.
Secondary Defenses: Tactics employed after an attack/detection.
- Alarm Calling: Warning others of a predator.
- Immobilization (death feigning): Pretending to be dead.
- Flight: Escaping from the predator.
- Chemical Defense: Using toxins (toxin sequestering).
- Attack: Mobbing behavior to deter the predator.

Taste aversion, also known as the Garcia effect (Garcia & Koelling, 1966), is a form of classical (or Pavlovian) conditioning.
It involves associating a particular taste (food or drink) with nausea, sickness, and/or vomiting.
Key features:
- Requires only a single pairing for the association to form.
- Can tolerate a long interval between food intake and illness onset.
- Specific to the taste-illness modality.
- Great adaptive value for avoiding poisonous food in the future.
John Garcia (1917 – 2012) was a key researcher in this area.

Acute vs. Chronic Stress:
- Beneficial (Acute):
  - Energy mobilization
  - Fight-or-flight response
- Deleterious (Chronic):
  - Reproductive suppression
  - Depressed immune response
  - Arrested growth
  - Eventual premature death

Adaptation can occur at two levels:
- Evolution: Changes at the species level.
- Development: Changes at the individual level.

Predator cues can have developmental effects on various organisms, including:
- Invertebrates
- Fish
- Amphibians
- Snowshoe hare
Examples of developmental changes:
- Changes in body shape and size
- Body armature
- Chemical defenses
- Timing of life-history traits (metamorphosis)
Leverets from stressed mothers during gestation:
- More stressed
- Smaller size
- More vigilant & active
- Epigenetic programming of the HPA axis

Genetic: Changes in genes that involve changes in the DNA sequence
Epigenetic: Heritable changes in gene function that do not involve changes in the DNA sequence