2: Mechanisms of predation

Question 1

Prey death function =

Answer 1

Predator growth function (conversion of biomass, dead prey = new predators)

Question 2

Describe a predator pop. in terms of functions

Answer 2

predator growth function - predator death function

Question 3

Describe a prey pop. in terms of functions

Answer 3

prey growth function - prey death function

Question 4

What is the functional response we are interested in when looking at predator/prey relationships?

Answer 4

the eating function, predator consumption rate depends on prey density

Question 5

Describe type 1 functional response

Answer 5

linear rate

Question 6

Describe type 2 functional response

Answer 6

Predator gut capacity isn’t infinite, eventually consuming plateaus

Question 7

Describe type 3 functional response

Answer 7

Different densities of prey (not constant) then plateau due to max consumption rate
= s shaped curve

Question 8

What is the mortality rate (in relation to prey)?

Answer 8

Ho many prey get eaten relative to prey density

Question 9

Describe the prey mortality rate of type 1 consumption rate

Answer 9

Constant (flat line)

Question 10

Describe the prey mortality rate of a type 2 consumption rate

Answer 10

Mortality rate decreases with prey density and becomes independent

Question 11

Describe the prey mortality rate of a type 3 consumption rate

Answer 11

Mortality rate increases (exponentially) then decreases with density as satiation hits
= Density dependent mortality (only when prey density is low)

Question 12

Which consumption rate is most common in the real world?

Answer 12

Type 2
→ predation is most likely to destabilise
Only type III generates stabilising density dependence and is rare
Type II does opposite as is v common

Question 13

What is required for coexistence?

Answer 13

Density dependence
- Predation, competition & disease require density dependence for coexistence

Question 14

What is the regulating process in a single pop. logistic growth equation?

Answer 14

density dependence is a regulating process that allows for coexistence among individuals and stable pop. at K

Question 15

In predator-prey or consumer-resource interactions what things are needed for coexistence?

Answer 15

Coexistence ONLY occurs if:
There is type 3 functional response
or
strong intraspecific competition (density dependence in prey or predator)

Question 16

What is optimal foraging theory?

Answer 16

are organisms choosey or do they eat at random?

Question 17

What is the contingency model of foraging?

Answer 17

Profit = E / h
(E= energy, h = handling time)
→ predators choose more profitable item, when search costas are ignored
- They add items to diet that increase enegry intake, but ONLY if new item has more energy than it takes to search for and handle