Topic 19 -Predation

Question 1

Fitness depends on an individuals ability to grow, survive and reproduce it requires…

Answer 1

suitable environmental conditions (abiotic factors)

sufficient resources to acquire appropriate quantities of energy and acquire energy efficiently (gain>loss)

Question 2

Predation

Answer 2

an individual of one species (predator) consumes all or part of a living individual of another species (prey)

Question 3

Predation does not include

but includes

Answer 3

scavengers or decomposers

blood feeders

Question 4

What are the 3 predation categories

Answer 4

Herbivory
Carnivory
Parasitism

Question 5

herbivory

Answer 5

prey is plant or algae

Question 6

carnivory

Answer 6

prey is an animal, predator is typically also an animal

Question 7

parasitism

Answer 7

for those parasites that feed on host tissues

Question 8

Specialist

Answer 8

an individual takes one or a few prey items

Question 9

Generalist

Answer 9

an individual takes many prey items

Question 10

preference

Answer 10

proportion of a prey type in the diet is higher than in the environment

Question 11

what does preference depend on

Answer 11

Energy content of prey

Nutritional content of prey (vitamins and minerals)

Question 12

switching of preference depends on

Answer 12

the abundance of different prey types

Question 13

“Prey switching”

may not occur right away if….

Answer 13

switching to increased consumption rates of a more abundant prey type

may not occur right away if predator still operates on search image of the prey type that used to be abundant

Question 14

Profitability

Answer 14

net energy gained after energy is spent capturing and consuming the prey

Question 15

Search time

Answer 15

search efficiency for prey

Question 16

Handling time

Answer 16

time to pursue, subdue and ingest prey

Question 17

Increased search and handling time both operate to

Answer 17

reduce consumption rate of predators

Question 18

Increased size of prey population decreases

Answer 18

search time and in some cases can decrease handling time

Question 19

Passive and filter feeders functionally have a handling time of

Answer 19

zero (spider web)

Question 20

in general consumption rates and prey population size have a

Answer 20

linear relationship until saturation

Question 21

at very low population sizes consumption rates will decrease disproportionately which means

Answer 21

need to learn new capture strategies

prey switching has not occurred yet

Refuges exist -hiding spots for prey

Question 22

what is the goal of Optimal foraging theory

What is it based on

What does it offer

Answer 22

predict the optimal foraging strategy under certain conditions

based on mathematical models derived from economics

offers a powerful way to understand foraging decisions of predators

Question 23

Assumptions for optimal foraging theory

Answer 23

foraging behaviour enhances fitness (i.e. foraging strategy= a behavioural trait favours by natural selection in the past)

animals maximize net energy gain ensures high fitness

Question 24

predators must expend energy to obtain prey

energy loss:
energy gain:

Answer 24

searching and handling time

consumption

Question 25

Diet model
if the predator knows how profitable each prey type is

specialist-

generalist-

Answer 25

energy lost searching ~ consume more profitable prey

consume less profitable prey~ low energy searching

Question 26

In terms of the environment if search time is > handling time

Answer 26

A generalist strategy would be best ex raccoon

Question 27

In terms of the environment if handling time is > search time

Answer 27

A specialist strategy would be best ex lion

Question 28

Optimal foraging theory Model assumptions

Answer 28

Predators know everything about foraging environment

predators perform complex mathematics to determine the profitabilities of prey types

Question 29

Optimal foraging model predicts

Answer 29

individuals that approach the optimal strategy will have higher fitness

Question 30

predators may use general rules

Answer 30

ex take the less profitable prey type after searching for a fixed amount of time

Question 31

predators may not maximize net energy gain

Answer 31

ex take less profitable prey type with a specific dietary requirement -nutrient, vitamin

Question 32

predators may minimize their own risk of predation

Answer 32

ex take a less profitable prey type to avoid foraging near a predator

Question 33

Optimal foraging theory assumes prey is limited and not highly mobile, it…

Answer 33

works off the habitat patch concept

Question 34

a foraging animal should leave a patch when consumption rates

Answer 34

drop below the average for the range

Question 35

giving up time

Answer 35

the point at which consumption rates become average and to maximize energy gain the animal should leave the patch

Question 36

OFT also is heavily influenced by the distance between patches, the individual will

Answer 36

stay longer if the next patch is far away