Predation

Question 1

Symbiosis

Answer 1

Unlike organisms living together, independent of the outcome

Close association between 2 different organisms living together (prolonged physical intimacy)

Question 2

Commensalism

Answer 2

One species benefits, the other is unaffected

Question 3

Amensalism

Answer 3

One species suffers, the other is unaffected

Question 4

Competition

Answer 4

Both species suffer
Usually due to resources being limited (or perceived to be limited)

Question 5

Predation, parasitism

Answer 5

One species benefits, the other suffers

Question 6

Neutralism

Answer 6

Neither species benefits or suffers from the interaction

Question 7

Mutualism

Answer 7

Interaction between 2 species that benefits both of them

Key to origin of eukaryotic cells (mitochondria and chloroplasts)
Key to land colonisation by plants (symbiotic fungi)

Question 8

Reciprocal exploitation

Answer 8

Each partner is a net beneficiary

Question 9

Predation

Answer 9

The consumption of one organism, in whole or in part, by another, where the consumed organism is alive when the consumer first attacks it

Question 10

‘True’ predators

Answer 10

Kill and eat their prey

Question 11

Grazers

Answer 11

Often eat part of the organism they are consuming
Usually herbivores

Question 12

Parasites

Answer 12

Obtain nutrients from one or a few individuals and are harmful but may not be deadly - often symbiotic

Question 13

Parasitoids

Answer 13

Insects in which the larva develops inside a single host which is ultimately killed

Question 14

Effects of predation on prey populations

Answer 14

Suppress populations of prey
Can have little influence on numbers of prey even though they eat a large proportion of the population- other factors may control the prey population
Can actually increase prey population through indirect interactions

Question 15

Tools to investigate predation

Answer 15

Observations of natural phenomena
Natural experiments
Carefully manipulated experiments in lab and field

Question 16

Detritovores

Answer 16

Organisms that eat dead organisms

Question 17

What is the classic study of predator -prey interactions

Answer 17

Snowshoe hare cycle

Question 18

Predator prey cycle hypotheses

Answer 18

Prey run out of food – predators follow
Predators run out of food by eating too many prey
Prey numbers build up and they get diseased at high densities
Something else is responsible for both predator and prey abundance (e.g. weather)
Some combination of above

Question 19

Predator mediated coexistence

Answer 19

Predators can maintain diversity by feeding on the competitively dominant species in the community

Question 20

Forcing variable for snowshoe hares

Answer 20

Number of sunspots seems to affect numbers

Question 22

How do predators respond to prey populations

Answer 22

Numerical response
Functional response

Question 23

Numerical response

Answer 23

Change in the population in response to the density of prey
Consists of reproduction and aggregation

Question 24

Functional response

Answer 24

Relationship between rate of consumption by a predator and the density of prey
Types I, II, III

Question 25

Type I functional response

Answer 25

linear – the more food the more is eaten (no processing or searching time)

Question 26

Type II functional response

Answer 26

decelerating – there is processing time (handling, eating) leading to a maximum intake rate

Question 27

Type III functional response

Answer 27

accelerating up to a maximum – (possibly due to learning or switching to the most abundant prey)

Question 28

How do numbers of predators and prey determine each other

Answer 28

dN/ dt = rN - a’CN dN/dt = rate of change in population size dN = rate in change of numbers dt = rate of change in time N = population size r = per capita rate of growth a’ represents searching efficiency or attack rate of predator C is the number of predators

Question 29

How does the predator population change

Answer 29

dC/dt = fa’CN - qC C is the number of predators q is predator mortality rate a’CN is the rate at which food is consumed f is the predator’s efficiency at turning food into baby predators If there is no food predators die and fail to reproduce….

Question 30

Behavioural impacts

Answer 30

Predators change the behaviours of their prey (not just numbers) ‘Landscapes of fear’ – prey avoid areas perceived as risky One US study quantified significant financial benefit of reduced collisions between deer and vehicles when wolves were present

Question 31

Lotka - Volterra equations for prey and predators

Answer 31

prey = dN/dt = rN = a’CN Predators dC/dt = fa’CN = qc

Question 33

Holling’s functional responses of predators to prey density

Answer 33

Type I/II/III X axis = density of prey population Y axis = number of prey consumed