5: avoiding predation Flashcards
what is adaptation? in what 2 ways may it arise?
heritable trait that enhances fitness of its bearer
- by current benefits
- by past benefits and evolutionary history
is every factor that reduces predation an adaptation against predation?
no
list the 3 main ways that not all behaviours/current traits are adaptive
- trait adaptive to past conditions that no longer exist
- trait may be an incidental maladaptive side effect of another adaptation
- not yet evolved to a recent change in the environment
why may a trait being adaptive to past conditions make it non-adaptive + 2 examples? (3)
- 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
how may a trait being a maladaptive side effect of another adaptation prove to be non adaptive? + examples (4)
- 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
what did Kruuk 1964 predict for mobbing in nesting gulls?
- what did he measure?
if mobbing intruders is a behavioural adaptation against egg predators then it should reduce egg predation
- measured mobbing and egg predation
what did Kruuk 1964 discover about mobbing on crows?
mobbing greater inside the colony so the egg predation is less on the inside as mobbing works to lower predation and increase reproductive success
what is the comparative method and when is it used? (4)
- 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
if mobbing is an adaptation then when would we only expect to see it?
only where effective or necessary
mobbing isnt needed in cliff dwelling gulls
- what was found because of this?
no mobbing of ground predators in cliff nesting kittiwakes on ground intruders
in the gull phylogeny what is derived and which species lack it/do mob?
cliff nesting
kittiwakes lack mobbing behaviour
all ground nesting gulls mob
in swallows some species have lost mobbing over evolutionary time- why is this and what species?
the traits are derived within their phylogeny and group
- solitary nesting rough winged swallows
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?
divergent
divergent
convergent
what are the 4 main anti predator adaptations?
anti-detection
anti-attack
anti- capture
anti-consumption
what is the anti-detection adaptation? (5)
- crypsis: hiding from prey
- camouflage such as mantidactylus frog looking like dead leaves
- transparency such as ribbon eel larvae
- nocturnality
- subterranean living
what is the anti-attack adaptation? (6)
- 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
what is the anti-capture adaptation? (6)
- 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
what is the anti-consumption adaptation? (5)
- 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
what do selfish herds reflect?
counterintuitive logic
what is the camouflage in the peppered moth?
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
what are 2 important things to remember about camouflage?
- may involve any of the senses, not just vision, such as olfaction
- either or both prey and predator may be camouflaged
how did Pietrewicz and Kamils study involving blue jays test camouflage? (4)
- 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
what do decorator crabs do to hide from predators?
pile algae, coral, anemone on their backs and allow them to grow
in decorator crabs when tested on in a predatory fish area what was found to be the prefered choice of species to grow?
Dictyota menstrualis
5 times less likely predated if grow the prefered algae
- it contains chemical that is toxic to omnivorous fish
what is stotting?
jumping up 0.5-1 m in air with legs straight and white rump patch fully visible
what did Thomson notice about gazelles stotting and the likely hypothesis for it? (4)
- 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
what is the anti-ambush hypothesis for stotting gazelles and why is it incorrect?
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
what is the alarm signal hypothesis for stotting gazelles and why is it incorrect?
stotting warns conspecifics especially offspring that a predator is near
- but solitary animals also stot and show rump to predators
what is the social cohesion hypothesis for stotting gazelles and why is it incorrect?
stotting enables gazelles to form groups and flee in a coordinated manner
- but solitary stot and show rump
what is the confusion effect hypothesis for stotting gazelles and why is it incorrect?
confuses and distracts predators preventing it from focusing on one animal
- but solitary stot
what did Caro 1986 discover when observing outcomes of predation attempts of gazelles that stot and those that dont?
- 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
when considering the selfish herd what did Hamilton 1971 discover?(4)
- 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
selfish herding can affect positioning behaviour- how is this the case in bluegill sunfish?
- 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
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
larger group means less chance of an individual being eaten
a) 0.125
b) 0.0125
give 4 points about whirligig beetles
- 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
what was discovered about selfish herding and the dilution effect in whirligig beetles? (4)
- 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
what is the mayfly emergence dilution effect? (4)
- 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
how are seabird egg laying and coral spawning synchronous ?
- may satiate gulls preying on fledging chicks
- may satiate animals preying on the gametes
what is vigilance like in group formation?
increased so may reduce predator attack
what was Kenwards experiment 1978 on the goth hawk and wild pigeons? (4)
- 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
why can grouping be considered costly?
increased food competition
sparrows may feed alone or in groups- what determines this?
- when low predation risk sparrows choose to be solitary
- when high choose to be in groups for extra vigilance
in an experiment on vigilance in sparrows what was done/found? (4)
- 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
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?
a) Automeris
b) do startle but markings more similar to eyespots have a greater anti predator impact
