Antipredator behaviour Flashcards
Species evolve adaptions to block what?
-detection
-attack
-capture
-consumption
Examples of species that avoid detection by foraging at night
- Banner-tailed kangaroo rats
- Jamaican fruit bats
What is cryptic behaviour and what animal is it seen in?
It is when an animal chooses a background that matches itself
- Seen in peppered moth: camouflaged on lichen
What adaptions are used to make attack less likely?
- Chemical defences
- Warning colouration
- Batesian mimicry
- Associating with a protected species
- Advertising unprofitability to deter pursuit
What are some examples of chemical defences?
Sprays
Injections
Toxins
Sticky secretions
What is aposematism?
When animals are poisonous and advertise it by warning colouration
What is mullerian mimicry?
When a poisonous species has the same warning colouration of another poisonous species e.g wasp & cinnabar moth caterpillar
What is batesian mimicry?
When a harmless species resembles a poisonous species e.g. Tephritid fly resembles jumping spider
What is batesian mimicry?
When a harmless species resembles a poisonous species e.g. Tephritid fly resembles jumping spider
An example of an animal that associates with a protected species
anemone hermit crabs use anemones for defence
How do animals advertise unprofitability?
Stotting
What are the alternative hypotheses to explain stotting?
- As a signal to other gazelles
- Alarm signal
- Group formation-flee together - Signal to predator
- Advertisement for unprofitability
What were the observations of the alternative hypotheses for stotting?
-Solitary gazelles stott
- Turn white rump to predator
- Predators more likely to abandon hunt when gazelle stots
Observations support the pursuit-deterrence hypothesis
How do animals adapt to make capture less likely?
- Startling predators e.g. sudden flashing of eyespots
- Rapid escape flight
- Group vigilance
How does a Bombardier beetle make a last ditch attempt to escape?
Creates an explosion (noxious spray) to deter predators
Describe the noxious gas ejected by the Bombardier beetle
- Explosive gas (100 degrees celcius)
-Made up of hydrogen peroxide & hydroquinones mixed with enzymes
How do animals misdirect a consumer?
Regenerate their tail if it is lost
False head deflects outcome in cabbage white butterflies
Butterflies with false heads added escape more often than those without
How do animals attract competing consumers?
- Fear screams
- Release of fear chemicals into water
Example: Pike take longer to handle minnow when competitor present
What are the possible explanations for fear screams?
- pain (not adaptive)
- warning (but not easy to locate, and ignored by
others) - call parents (but adults as likely to scream)
- alarm predator (maybe?)
- call competing predators
What observation was seen in recording starling fear screams?
recording of starling fear scream attracted foxes, cats and hawks, supporting the hypothesis that fear screams attract competing predators
Why are prey always one step ahead in the arms race?
- Have a shorter generation time
- Life –dinner principle (Dawkins & Krebs) fox runs for his dinner, rabbit for his life!
Examples of predator adaptations and counter-adaptations by prey
See Antipredation lecture notes slide 32
What is an evolutionary arms race?
-Natural selection results in predators with increased efficiency in finding and capturing prey
-The selection for prey’s ability to avoid
detection and capture
-Each improvement in the predator will put pressure on the prey to evolve counter-adaptations, and vice versa
How have adaptions of crypsis and visual acuity evolved in prey?
Blend in with background resulting in increased survival of those that blended in
-Better cryptic colour/behaviour selected in prey
What is the predator adaption to crypsis and vision acuiity?
Prey harder to find- selection for better vision/search
image formation in predator
What selections have evolved for predators?
-selection on predator for better vision and ability to form a search image
-selection on prey to improve crypsis, also polymorphism (e.g. underwing moths)
What are the defences used by underwing moths against predation by jays?
-Forewing: crypsis to avoid detection
-Hind wings: startle to avoid capture
Jays detect fewer moths on cryptic background
What is the result of variation in colour of the hind and fore wings in underwing moths?
Hinders learning by the predator and helps the moths to escape
What occurs as a result of polymorphism in crypsis?
it impedes formation of a search image by predator
What occurs as a result in variation in startle?
colour impedes learning (habituation)
An example of a species that shows polymorphism?
The forewings of Catacola are polymorphic- different varieties within one population
- Helps avoid detection by interfering with formation of a search image
Describe the experiment to show variation in startle colour impedes learning
- Hind wings startle jays
- Jays habituate to a particular pattern after repeated presentations
- But still startled by a different hind wing pattern
What is habituation?
A stimulus-specific decline in response
to a repeated stimulus
not associated with reward or punishment
How do forewings effect the relationship between underwing moths and jays?
- Forewings reduce detection (on appropriate background)
- Detection improves with experience: jays form search image
- Polymorphism in moths interferes with search image formation
How do hind wings effect the relationship between underwing moths and jays?
Jays habituate to hindwings
– but habituation is pattern-specific
Adaptive for hindwing patterns of
sympatric species to differ markedly
Trade-off between crypsis and conspicuousness in guppies showed what?
- Male guppies more brightly
coloured than females - Brighter male guppies, with
more spots have mating
advantage
(sexual selection for spots
What species show trade-off between crypsis and mating success?
Distinctive colours lost after breeding season
-Mallard: drakes in mating season
What was seen in an experiment performed using guppies?
- Male guppies from streams with higher predation pressure
have fewer, smaller spots (selection against spots) - Guppies without predators (“k”) evolved to be brighter over
20 months (sexual selection for spots)
