BIOL 3410 Exam 4 Review
Predation & Herbivory
Objectives:
Contrast species interactions related to predation and herbivory.
Understand how predators and herbivores can limit the abundance of population.
Understand and apply the Lotka-Volterra model of predator-prey cycles.
Interpret predator-prey graphs.
Understand adaptations to minimize predation and herbivory:
physical defense
crypsis
behavior
chemical defense (constitutive versus inducible)
Types of Interactions Between Species:
Type of Interaction | Species 1 | Species 2 |
Predation/Parasitoidism | + | - |
Parasitism | + | - |
Herbivory | + | - |
Competition | - | - |
Mutualism | + | + |
Commenalism | + | 0 |
Predation - heterotropic organisms that consume tissue (plants, animals, or cells) as a source of energy
Typically distinguished from scavengers and decomposers because they feed on living organisms.
True predators eat other animals or insects (i.e. praying mantis, lions, etc.)
Exponential Growth:
\frac{\Delta N}{\Delta t}=rN
Lotka (1925) and Volterra (1926) developed mathematical models of population dynamics that take into consideration predator-prey interactions.
Prey (N) | Predator (P) |
\frac{\Delta N}{\Delta t}=rN-cNP P → number of predators NP → number of encounters c → efficiency of catching prey | \frac{\Delta P}{\Delta t}=a\left(cNP\right)-mP a → efficiency of converting captured prey into predators (~10%) ac → efficiency of catching and converting prey into predator growth m → predator mortality rate |
For stability, both \frac{\Delta N}{\Delta t} and \frac{\Delta P}{\Delta t} must equal 0.
When \frac{\Delta N}{\Delta t}=0 , then rN=cNP ,