Lecture 5- Predation avoidance

Question 1

examples of useful predation avoidance adaptations

Answer 1

dilution
escape
vigilance
hiding
camouflage- counter-shading and disruptuve colouration (crypsis, eucrypsis, masquerade)

Question 2

Hamilton’s ‘dilution’ idea

Answer 2

the domain of danger decreases in a more diluted herd (spatial, in terms of time etc), therefore leading to every animal wanting to partake in this behaviour

Question 3

what is ‘escape and hiding’

Answer 3

a means of avoiding predation that is more direct and individual- often includes signalling that you are good at escaping, in hopes of moving the predator to another individual

Question 4

example of how vigilance/food trade offs can change

Answer 4

ostriches spending more time feeding when they are in groups- group makes overall vigilance higher, but shorter times for individuals

Question 5

example of movement in an attempt to hide

Answer 5

snakes moving more gently- doesn’t trigger prey’s perception as the movement is similar to leaves etc

Question 6

what is counter-shading

Answer 6

using selective body darkening to counteract light- fish do this a lot where light shines from above, darker dorsal pigmentation

Question 7

shape-scrambling example

Answer 7

marine crabs putting material on themselves, ireegular protrusions on Sargassum fish, irregular wing shape on Comma butterfly

Question 8

disruptive colouration + example

Answer 8

high-contrast and conspicuous shapes which look non body-like
mammals which conceal eye shape (Vizacha)

Question 9

study that showed the importance of shape in predation

Answer 9

fake moths put on trees, ones with messed up edge colouration survived best

Question 10

crypsis

Answer 10

colour matching with the background to avoid detection

Question 11

crypsis example

Answer 11

caterpillars being green against plants

Question 12

eucrypsis vs masquerade

Answer 12

eucrypsis is general colour matching and generally targets detection, masquerade is specifically looking like an object like a leaf or stick and targets recognition

Question 13

stages of predator cognition

Answer 13

detection (filtering out kinds of movement) and classification (recognising prey compared to other items)

Question 14

reflexive polymorphism

Answer 14

polymorphism within a population, but where individuals seem to present a random selection of background elements rather than having a set number of morphs

Question 15

aposematism

Answer 15

warning colouration

Question 16

how might aposematism be useful with regards to receiver psychology

Answer 16

conspicuousness may be more:
memorable (evidence for this in chicks and distasteful food)
discriminable
prone to causing recognition errors

Question 17

evidence for aggregation being useful in learning to avoid bad stimuli

Answer 17

learnt (visual) aversions to bad crumbs in chicks stayed longer once the stimulus was no longer bad when they were aggregated compared to solitary

Question 18

mimicry

Answer 18

evolved visual resemblances that help in avoiding predation, e.g. by mimicking aposematism

Question 19

batesian vs mullerian mimicry

Answer 19

batesian- non-toxic mimic of a toxic species, or similar
mullerian- mimic and original species are both unpalatable

Question 20

example of density dependence being maintained

Answer 20

mocker swallowtail- species of butterfly where only the female morph mimics toxic butterflies, and the butterfly they mimic differs