Week 9 Monday

Question 1

What are the assumptions of the predator prey model?

Answer 1

1. In the absence of predators, prey will experience exponential growth
2. In absence of prey, predators will decrease exponentially
3. The system is closed
4. Predators move randomly among prey
5. The proportion of encounters is constant
6. The number of prey taken increases in proportion to the number of predators
7. All responses are instantaneous
8. Energy is immediately converted

Question 2

how can prey populations persist in the presence of predators?

Answer 2

• Avoid detection and/or reduce attacks

Question 3

how do they avoid attacks/detections?

Answer 3

• camo
• warning colour
• become better hider
• look less edible

Question 4

what is crypsis?

Answer 4

the ability of plant or animal to avoid observation or detection

Question 5

what is aposematism?

Answer 5

a signal made by an animal that it is not worth attacking or eating that advertises that is toxic

Question 6

what can form of signals can aposematism be?

Answer 6

• colouration
• sounds
• odours

Question 7

what is mullerian mimicry?

Answer 7

co-mimicry among several species of noxious species (Honest signal)

Question 8

what is batesian mimicry?

Answer 8

the evolution of a non-noxious species to resemble a toxic or inedible species (dishonest signal)

Question 9

what is refuge?

Answer 9

a condition of being safe or sheltered from pursuit, danger, or trouble

Question 10

what is structural refugia?

Answer 10

• habitat complexity
• areas that exclude predators (inaccessible)

Question 11

why does grouping together reduce the likelihood of any individual being eaten?

Answer 11

• break free of predator pressure through shear abundance
• predator do satiate
• facilitates cooperative vigilance, reducing risks for the group ( more eys hyp)

Question 12

describe protection in size

Answer 12

• large individuals are ignored by predators then large size may be a form of refuge
• may select for individuals that grow rapidly through a window of vulnerability or apprear to be larger than they are

Question 13

what is the red queen hypothesis?

Answer 13

predicts that measures and countermeasures should become more complex in evolutionary times

Question 14

what is stable cycling based on?

Answer 14

frequency-dependent selection

Question 15

what is stable cycling?

Answer 15

• relies on defenses and countermeasures being controlled by a single gene
• success of the prey will increase with presence of the defensive gene, and eventually all will have it but if the predator then evolves a different strategy that requires a different defense, those with that will increase and the other ones will be at a fitness disadvantage

Question 16

what is mutualism?

Answer 16

interactions between individuals of different species that benefit both partners

Question 17

what is the difference of obligate and facultative mutualism?

Answer 17

obligate is dependent on the relationship, but facultative is not

Question 18

what are some examples of obligate mutualism?

Answer 18

ants

Question 19

examples of facultative mutualism?

Answer 19

pollinating birds

Question 20

what is parasitism?

Answer 20

• parasites live in or on tissues of their host
• host is not immediately killed, but there are often negative fitness consequences and excessive parasitism can lead to death