Trophic Interactions in Ecological Communities Flashcards
What examples of predation exist?
Broad definition
-Herbivory
-Carnivory
-Insect Parasitoids
-Parasitism
-Cannibalism
Why is predation hugely important within ecological communities?
-Predators may influence the distribution and abundance of their prey and vice versa
Describe lemmings
-Lemming populations in Arctic and Alpine habitats display regular density oscillations every 4 years
-Cycle is thought to be driven by fluctuations in food
-Lemmings are specialist herbivores feeding on moss, as lemming numbers increase, moss becomes depleted, resulting in a crash in lemming density. Once moss is allowed to re-grow, lemming numbers recover
Describe the relationship of the Canada Lynx and the snowshoe hare
-Hudson bay, records of fur trappings provide a 100 year record of population fluctuations in both species
-Both species showed regular oscillations over 8-10 years intervals
-Evidence suggests that this cycle is driven by both predation of lynx on the hares and the availability of the hares food
-Lynx depend on hares and are food-limited
-Hares are both food and predator limited
How can a simple predator prey cycle be recreated?
Using Lotka-Volterra (1962) model
-based on the exponential growth model
What does H stand for?
Density of prey
What does P stand for?
Density of predators
What does r stand for?
Rate of prey population increase in the absence of predation
What does a stand for?
Number of prey consumed per predator per unit of time
What does b stand for?
Reproduction rate of predators per 1 prey eaten
What does m stand for?
Predator mortality rate
Describe the Lotka-Volterra predator-prey cycle
-The abundance of predators and prey will fluctuate in response to each other
-When prey abundance is high, predator abundance increases
-Ultimately predators exhaust their food supply - prey decline and then predators decline
-Once the predator population reaches a low level the prey population can increase again
What ways is the Lotka-Voltera model is unrealistic?
In many ways unrealistic
-Predator prey can develop in highly seasonal and extreme environments (Arctic) where specialist predators feed exclusively on one prey species
Describe predator-prey dynamics
-Multi-species system: both the predator and prey are influenced by other ecological interactions (predation of predators, competition between prey)
Describe predator-prey dynamics
-Multi-species system: both the predator and prey are influenced by other ecological interactions (predation of predators, competition between prey)
-Many predators take more than one prey, and generalist predators are not tightly tied to the dynamic of any one prey species
