5: avoiding predation

Question 1

what is adaptation? in what 2 ways may it arise?

Answer 1

heritable trait that enhances fitness of its bearer

• by current benefits
• by past benefits and evolutionary history

Question 2

is every factor that reduces predation an adaptation against predation?

Answer 2

no

Question 3

list the 3 main ways that not all behaviours/current traits are adaptive

Answer 3

1. trait adaptive to past conditions that no longer exist
2. trait may be an incidental maladaptive side effect of another adaptation
3. not yet evolved to a recent change in the environment

Question 4

why may a trait being adaptive to past conditions make it non-adaptive + 2 examples? (3)

Answer 4

• persists as there is insufficient time/appropriate mutations to prevent the replacement of the trait
• some arctic moths fly where are no bats but will stop locomotion when exposed to experimental ultrasonic stimulus
• arctic ground squirrels live where no snakes but if exposed will respond how other squirrel species do that live in the range of predatory snakes

Question 5

how may a trait being a maladaptive side effect of another adaptation prove to be non adaptive? + examples (4)

Answer 5

• may be genetically linked to another with a selective advantage
• the drive to care is preferentially for offspring
• female rodents in communal nests may give milk to offspring that isn’t their own due to strong parental drive
• stepparents may more likely abuse children even though it reduces their own fitness

Question 6

what did Kruuk 1964 predict for mobbing in nesting gulls?

- what did he measure?

Answer 6

if mobbing intruders is a behavioural adaptation against egg predators then it should reduce egg predation
- measured mobbing and egg predation

Question 7

what did Kruuk 1964 discover about mobbing on crows?

Answer 7

mobbing greater inside the colony so the egg predation is less on the inside as mobbing works to lower predation and increase reproductive success

Question 8

what is the comparative method and when is it used? (4)

Answer 8

• method to test evolutionary hypotheses by comparing different taxa
• to see if 1 factor causes another by seeing
• if presence/absence of 2 factors is correlated
• correlate occurance of traits with benefit of trait

Question 9

if mobbing is an adaptation then when would we only expect to see it?

Answer 9

only where effective or necessary

Question 10

mobbing isnt needed in cliff dwelling gulls

- what was found because of this?

Answer 10

no mobbing of ground predators in cliff nesting kittiwakes on ground intruders

Question 11

in the gull phylogeny what is derived and which species lack it/do mob?

Answer 11

cliff nesting
kittiwakes lack mobbing behaviour
all ground nesting gulls mob

Question 12

in swallows some species have lost mobbing over evolutionary time- why is this and what species?

Answer 12

the traits are derived within their phylogeny and group

- solitary nesting rough winged swallows

Question 13

what is the evolution in the loss of mobbing from the ground nesting ulls to kittiwake, from colonial nesting swallows to rough winged and between kittiwakes and rough winged swallow?

Answer 13

divergent
divergent
convergent

Question 14

what are the 4 main anti predator adaptations?

Answer 14

anti-detection
anti-attack
anti- capture
anti-consumption

Question 15

what is the anti-detection adaptation? (5)

Answer 15

• crypsis: hiding from prey
• camouflage such as mantidactylus frog looking like dead leaves
• transparency such as ribbon eel larvae
• nocturnality
• subterranean living

Question 16

what is the anti-attack adaptation? (6)

Answer 16

• protects animals detected by predators
• springbok will stot
• selfish herding
• mimicry and warning colouration
• stinging nettle slug caterpillar has toxic spines
• horned lizard squirts blood from its eyes which is noxious to dogs

Question 17

what is the anti-capture adaptation? (6)

Answer 17

• once predator is attempting to catch they prey
• vigilance
• run, swim , fly fast
• grasshopper jumps
• body part autonomy
• northern alligator lizard sheds its tail in response to capture attempt

Question 18

what is the anti-consumption adaptation? (5)

Answer 18

• fighting back
• releasing noxious chemicals
• faking death
• being hard to swallow
• porcupine puffer fish inflates with water and its covered in spines so is difficult to eat

Question 19

what do selfish herds reflect?

Answer 19

counterintuitive logic

Question 20

what is the camouflage in the peppered moth?

Answer 20

Biston betularia

• 2 subspecies: light typica form and dark carbonaria form
• white form camouflaged in trees covered in lichen
• larvae are camouflaged to look like twigs

Question 21

what are 2 important things to remember about camouflage?

Answer 21

• may involve any of the senses, not just vision, such as olfaction
• either or both prey and predator may be camouflaged

Question 22

how did Pietrewicz and Kamils study involving blue jays test camouflage? (4)

Answer 22

• operant conditioning of blue jays to respond to white underwing moths
• detected fewer head up white moths on light bark, particularly those with wings upwards
• orientation important for detection
• behaviour of moths affects the ability of bird to detect them and their predation risk

Question 23

what do decorator crabs do to hide from predators?

Answer 23

pile algae, coral, anemone on their backs and allow them to grow

Question 24

in decorator crabs when tested on in a predatory fish area what was found to be the prefered choice of species to grow?

Answer 24

Dictyota menstrualis
5 times less likely predated if grow the prefered algae
- it contains chemical that is toxic to omnivorous fish

Question 25

what is stotting?

Answer 25

jumping up 0.5-1 m in air with legs straight and white rump patch fully visible

Question 26

what did Thomson notice about gazelles stotting and the likely hypothesis for it? (4)

Answer 26

- appear that they advertise themselves to predators - may be signalling to the predator that they've seen them and are fit to flee - predators wont bother chasing these animals that stot - unprofitability hypothesis

Question 27

what is the anti-ambush hypothesis for stotting gazelles and why is it incorrect?

Answer 27

lets gazelles see what is ahead and reduces chance of being ambushed and is costly so should only occur in long grass - but it occurs in all habitats including short grass

Question 28

what is the alarm signal hypothesis for stotting gazelles and why is it incorrect?

Answer 28

stotting warns conspecifics especially offspring that a predator is near - but solitary animals also stot and show rump to predators

Question 29

what is the social cohesion hypothesis for stotting gazelles and why is it incorrect?

Answer 29

stotting enables gazelles to form groups and flee in a coordinated manner - but solitary stot and show rump

Question 30

what is the confusion effect hypothesis for stotting gazelles and why is it incorrect?

Answer 30

confuses and distracts predators preventing it from focusing on one animal - but solitary stot

Question 31

what did Caro 1986 discover when observing outcomes of predation attempts of gazelles that stot and those that dont?

Answer 31

- stotting indicates quality as non-stotters were chased (30% compared to 50% chased) - predators chasing never successfully killed gazelles that stotted - caught and killed non stotters - is an honest signal of health and vitality

Question 32

when considering the selfish herd what did Hamilton 1971 discover?(4)

Answer 32

- best to sit next to another frog so arent the only target to a snake that may move in any direction - benefit to the individual but not the group - bunching may increase total predation risk by making it a more conspicuous target - benefit of the selfish herd outweighs the cost of conspicuousness

Question 33

selfish herding can affect positioning behaviour- how is this the case in bluegill sunfish?

Answer 33

- those that nest at edge of colony more likely attacked by nest predators - prefer to nest in the centre where are safer from egg predators

Question 34

selfish herding works by the dilution effect- what is this and what is the chance of being eaten by 5 predators a) in a group of 40 b) in a group of 400

Answer 34

larger group means less chance of an individual being eaten a) 0.125 b) 0.0125

Question 35

give 4 points about whirligig beetles

Answer 35

- sit on pond surface eating small insects - predated by fish beneath the water - larger groups are more attractive with a higher strike rate by predators - individual predation risk less in larger groups

Question 36

what was discovered about selfish herding and the dilution effect in whirligig beetles? (4)

Answer 36

- trade off in obtaining food vs predation risk - food more abundant at the edge of the group as has been eaten in the centre - predation risk is greater at the edge - if deprived of food will forage on the outside of the group

Question 37

what is the mayfly emergence dilution effect? (4)

Answer 37

- mayfly nymphs live in freshwater and adults are aerial - predation risk greater on days when fewer adults emerge - risk is lower when many adults emerge as predators such as birds become satiated after eating a lower proportion of flies - dilution effect will lead to synchrony of emergence

Question 38

how are seabird egg laying and coral spawning synchronous ?

Answer 38

- may satiate gulls preying on fledging chicks | - may satiate animals preying on the gametes

Question 39

what is vigilance like in group formation?

Answer 39

increased so may reduce predator attack

Question 40

what was Kenwards experiment 1978 on the goth hawk and wild pigeons? (4)

Answer 40

- released the hawk from a set distance of wild pigeons - pigeons noticed hawk from further away when lots of them - as number in flock increases the reaction time decreases as more warning and time to escape - larger flocks had fewer successful predation attacks

Question 41

why can grouping be considered costly?

Answer 41

increased food competition

Question 42

sparrows may feed alone or in groups- what determines this?

Answer 42

- when low predation risk sparrows choose to be solitary | - when high choose to be in groups for extra vigilance

Question 43

in an experiment on vigilance in sparrows what was done/found? (4)

Answer 43

- manipulated distance to predator (15m away or 25m away) - manipulated distance to safe cover (adjacent or 2m away) - fewer chirrup calls close to safe cover and far from predator - forage alone if no predation as can get more food avoiding competitive group foraging costs

Question 44

a) which moth has realistic eye spots that perhaps were not always realistic? b) when testing if any contrasting shape on the hind wing can startle birds what was concluded?

Answer 44

a) Automeris | b) do startle but markings more similar to eyespots have a greater anti predator impact