Populations - Predation and Herbivory

Question 1

Describe predator-prey dynamics

Answer 1

Predator-prey dynamics simultaneously oscillate to produce cyclical patterns. As prey increases, so will predators. Then prey will decrease in response to higher predation. This causes predator numbers to decrease because there is less food. Prey numbers increase in response to the lessening of predator pressure… and the cycle repeats.

Question 2

Predict the outcomes of predator-prey interactions

Answer 2

Predators can respond to prey density fluctuations according to numerical, functional, aggregative, and developmental models

Question 3

Link concepts between physical environment, populations & competition

Answer 3

The physical environment does not provide limitless resources - they must be competed for. The competition influences populations because successful individuals will pass their characteristics onto the next individuals. These individuals make up the population.

Question 4

How do the complex interactions between predators and prey impact population growth dynamics?

Answer 4

Both predators and prey are impacted by their own abundance and each other’s abundance

Question 5

Predation

Answer 5

One species of animal killing and consuming another species (interspecific)

Question 6

Herbivory

Answer 6

Animals eating plant tissues

Question 7

How do predators and herbivores limit population growth?

Answer 7

High prey populations can increase predator reproductive rate

Low predators can increase prey reproductive rate

Question 8

How do predators respond to prey abundance/density (4)?

Answer 8

Numerical, functional, aggregative, developmental

Question 9

Predator response to prey increase: numerical

Answer 9

Prey continues to increase at the rate of consumption

Question 10

Predator response to prey increase: functional

Answer 10

Consumption increases with increasing prey density

Question 11

Predator response to prey increase: aggregative

Answer 11

Predators move to areas of high prey abundance

Question 12

Predator response to prey increase: developmental

Answer 12

Consumption of prey varies with age

Question 13

Population growth of prey is a function of…

Answer 13

Initial prey abundance and predator abundance

Question 14

Population growth of predators is a function of…

Answer 14

Initial predator abundance and prey abundance

Question 15

Prey equilibrium

Answer 15

Number of predators needed to stabilize prey population

Question 16

Predator equilibrium

Answer 16

Number of prey needed to stabilize predator population

Question 17

Review cyclical predator and prey models - they are simultaneous

Question 18

What are the three types of predator functional responses to prey abundance?

Answer 18

Type I: consumption of prey remains constant despite changes in prey density (linear)

Type II: consumption of prey is increased by lower search times, but limited by handling time (asymptotic)

Type III: predators will switch to more abundant prey at a certain density, but consumption of prey is limited by handling time

Question 19

How have prey responded to predation?

Answer 19

Evolve defenses:

Behavioural, crypsis, structural, chemical

Question 20

How do plants defend themselves against herbivory?

Answer 20

Adaptations in structure, chemicals, and tolerance