ENVB 305 Lecture Notes - Lecture 11: Isocline, Carrying Capacity, Trophic Cascade

• School: McGill University
• Department: Environmental Biology
• Course: ENVB 305
• Professor: Christopher Buddle

Document Summary

Predator (p) and victim (v) dv/dt = rv v p . Capture efficiency (predation effect on the per capita growth rate of victims) = . Victim isocline (dv/dt = 0): p = r/ . If r/ increases, it will take more predators to decrease victims. Effect of predation on predator: dp/dt = v p qp. Conversion efficiency (predator converts fuel to its own per capita growth) = . Victim isocline (dp/dt = 0): v = q/ . If the death rate increases, more victims will be needed to sustain growth. Period of the cycle: c = 2 / ( rq) Victims grow exponentially in the absence of predators. The same number of predators can control any number of victims. Bottom-up- effects created by resources used by species. Trophic cascade- a change in one trophic level will affect the other trophic levels. Ex: if you decrease otters, sea urchins will increase, and kelp will then decrease.