BIO3052 Lecture Notes - Lecture 9: Bluegill, Social Group, Autotomy
30 May 2018
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PREDATOR-PREY INTERACTIONS I
• Predation involves 4 distinct components:
1. Detection eg. moth cryptic patterns to camouflage
2. Attack
3. Capture
4. Consumption
At eah step, prey ay e ale to respod adaptiely to loer the predator’s haes of suess
• Adaptive prey responses:
Minimising detection: prey may be able to reduce risk of predation by making detection less
likely. This can be achieved in a number of ways
o Crypsis: blend in with surroundings
eg. bird undergoes moult in winter -> white feather to blend in with snow
eg. underwing moths
eg. chemical crypsis in filefish
Experimental design: fed filefish either Acropora or Pocillopora coral diet (they
end up smelling like the coral they consume -> some protection against
predators?). Allowed either Acropora/Pocillopora dwelling crabs to choose
between odour cues (corals are specialised to crabs)
Results:
▪ Cra a’t tell the differee etee fish or atual oral (heial ues
are the same)
▪ When using either matching coral or different, the cod went to the fish
that was mismatched with its coral
▪ Coral-eating filefish use chemical crypsis to avoid predation
o In some cases background matching is not sufficient due to recognition of body contour
or outline
Solution: break contour (eg. stripes in zebras)
• Camouflage: animals use objects around them to obtain concealment
eg. corpse camouflage in assassin bugs – why do assassin bugs stack ant corpses on their backs?
o Experimental design: 2 treatments; either keep corpses or remove corpses and see
which ant the spider attacks
o Result:
Corpse camouflage resulted in greater protection from predation
• Adaptive prey responses: minimising risk of attack assuming prey has been detected
o Noxious or foul tasting flesh (eg. pufferfish)
o Stinging hairs (physical defences)
o Boiling sprays (eg. beetles have 2 chambers with 2 different chemicals, when faced with
predator chemicals mix and spray hot liquid)
o Sticky secretions/repellent regurgitates
o Painful bites/injections
find more resources at oneclass.com
find more resources at oneclass.com
• Aposematic colouration: unpleasant defence attributes are often communicated through
aposematic ie. Warning colouration/patterns (advertising unpalatability to deter predators from
future attacks)
• Associating with protected species: some species reduce the risk of attack by associating with
and making use of the defences of well protected species
Eg. nesting success of rufous-naped wrens
o Birds often nest in trees occupied by was nests (to gain protection?) against predation
by white faced monkeys
o Does nesting in trees with wasps affect fledgling success of birds?
o Experimental design: 2 groups; nesting tree with wasp nests added or nesting tree with
no wasps nest added (control) -> using trees with clean slate so no confoundings
o Results: More young fledged in trees with wasps
• Advertising unprofitability: animals may also reduce the risk of attack by advertising their
physical fitness (at evading capture) to would-be predators
Eg. Slotting behaviour in gazelle (high jumping behaviour)
o What is the purpose of stotting:
Anti-ambush?
-NO, gazelle stott in long grass (ambush is likely) as well as short grass (ambush
not likely)
Alarm signal
-NO, gazelle stott even when they are on their own
Social cohesion
-NO, gazelle stott even when on their own
Confusion
-NO, gazelle stott even when on their own
Signal of unprofitability
-YES, stotting tells predator that it has been seen and that the gazelle is ready
and fit to evade capture
-there is a physical limitation which makes sure signal is honest
• Startling would-be predators: some species startle predators to avoid attack
Eg. startle response of blue jays to moth hindwings
o Moths have striking underwing which acts as an additional way of mitigating attack if
detection fails
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Predator-prey interactions i: predation involves 4 distinct components, detection eg. moth cryptic patterns to camouflage, attack, capture, consumption. At ea(cid:272)h step, prey (cid:373)ay (cid:271)e a(cid:271)le to respo(cid:374)d adapti(cid:448)ely to lo(cid:449)er the predator"s (cid:272)ha(cid:374)(cid:272)es of su(cid:272)(cid:272)ess: adaptive prey responses: Minimising detection: prey may be able to reduce risk of predation by making detection less likely. Experimental design: fed filefish either acropora or pocillopora coral diet (they end up smelling like the coral they consume -> some protection against predators?). Allowed either acropora/pocillopora dwelling crabs to choose between odour cues (corals are specialised to crabs) In some cases background matching is not sufficient due to recognition of body contour or outline. Slotting behaviour in gazelle (high jumping behaviour: what is the purpose of stotting: No, gazelle stott in long grass (ambush is likely) as well as short grass (ambush not likely) No, gazelle stott even when they are on their own. No, gazelle stott even when on their own.
