6. Predators Flashcards
Four ways of reducing predation
Avoiding detection (crypsis)
Mobbing
Aggregation
Signalling to predators (stotting, tail flagging, aposematism)
What is crypsis?
Having inconspicuous colouration
Define mobbing behaviour
Mobbing is when a group of ‘prey’ attack/hassle a predator in order to distract them - e.g. divert attention away from nest/offspring
But is costly
There are three theories behind aggregation, what are they?
Diluting effect, Many eyes, Selfish herd
What is the selfish heard theory?
Individuals may gain by putting others in between itself and the edge
Penguins - the result of individuals acting selfishly to minimise own risk
Why may it be beneficial to have bright colours?
Chicks learn to avoid conspicuous prey items more quickly and more rapidly
How did warning colouration evolve?
Kin selection - Fisher 1930 - mutation arise in adult which causes larvae to be conspicuous - not beneficial to individual but very beneficial to siblings which carry the mutant gene
Direct advantage - often sampled individuals survive, secrete toxins etc - bright colour ensues predator will not sample again.
What is mullerian mimicry?
Convergence of warning signals
What is batesian mimicry?
Other species exploit warning signals of toxic/dangerous species
How can batesian mimicry be stable? (like dishonest signals)
When the mimics are less prevalent than the toxic
As the frequency of batesian mimics increases, what happens to their fitness?
It decreases.
How can an arms race begin?
Selection on existing variation
Small advantages in speed/agility can start the race
How do arms races end?
1) Prudent predation
2) Group extinctions
3) Prey are ahead in the arms race (shorter generation times)
4) Frequency dependant selection
All can lead to stable equilibrium or extinction
Cuckoo and host species are great examples of what?
Coevolutionary arms race
