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AVOIDING PREDATION • HOW NOT TO BE FOOD • Avoiding Predation Blue petrel Brown Skua Avoiding Predation Petrel courtship calls Attracts skua Petrels detect skua Petrels emit skua territorial call Cease courtship Avoiding predation Frog hatching times - Red-eyed tree frog - Agalychnis callidryas Avoiding predation Frog hatching times - Red-eyed tree frog - Agalychnis callidryas Avoiding predation Frog hatching times - Red-eyed tree frog - Agalychnis callidryas Wasp & snake predators Tadpoles hatch and drop into water Fish + insect predators Eggs on underside of leaves Avoiding predation Frog hatching times Avoiding predation Frog hatching times If predation is absent -hatch slowly Proportion hatched Consequence: Tadpole is large enough to avoid fish predation Day 4 Day 5 Day 6 Avoiding predation Frog hatching times If predation is strong Hypothesis: Eggs should hatch earlier Clutches under wasp predation Clutches under no predation Proportion hatched Age of clutch Avoiding predation Frog hatching rates If predation is strong Hypothesis: Eggs should hatch faster Clutches under wasp predation Clutches under no predation Hatch rate (egg/min) Age of clutch Avoiding predation Frog hatching times If predation is strong Hypothesis: Eggs should hatch earlier With snake predator With no predator % hatched Time (days) ALARM CALLS - VERVET MONKEYS VERVET CALLS Look up Stand up and search grass Group and hide in bushes Avoiding Predation 1. Escape and Freezing Crypsis Avoiding Predation 2. Deception Avoiding Predation 2. Deception - disruptive colouration Butterfly fish Avoiding Predation 3. Toxicity and aposematism Poison arrow frogs Avoiding Predation 3. Mimicry - Batesian Look like something distasteful Viceroy Monarch Avoiding Predation Mimicry - Müllerian A number of distasteful animals resemble one another Avoiding Predation - Group Effects And some of the benefits of being in groups a. Encounter Effect Grouped animals are more difficult to find Avoiding Predation - Group Effects And some of the benefits of being in groups b. Dilution Effect 1:9 1:1000’s Groups and Predator Inspection Sometimes prey approach predators -called inspection, harassment, mobbing, boldness Why? 1. Decrease current risk 2. Information gathering about threat 3. Warn other group members Groups and Predator Inspection Herds from <10 to >500 Groups and Predator Inspection Probability of group approaching predator 0 200 400 Group size 600 Groups and Predator Inspection 4000 Distance cheetah walked away from group (m) 3000 2000 1000 0 0 200 400 Group size 600 Groups and Predator Inspection Stotting Stotting video Groups and Predator Inspection Possible Function Relevant information 1. Alarm signal - isolated animals stott 2. Social cohesion - orient rump to predators 3. Confusion effect - isolated animals stott 4. Pursuit deterrence Groups and Predator Inspection With stotting Hunt abandoned Chase failed Gazelle killed Without stotting Predator/Prey Arms Races Red Queen Hypothesis "Well, in our country," said Alice, still panting a little, "you'd generally get to somewhere else — if you run very fast for a long time, as we've been doing." "A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!" For an evolutionary system, continuing change is needed just so that one species can maintain its fitness relative to the species with which it is co-evolving. Predator/Prey Arms Races Red Queen Hypothesis Example: Passiflora and Heliconius Passiflora Heliconius Predator/Prey Arms Races Red Queen Hypothesis Example: Passiflora and Heliconius Develops chemical defenses Develops chemical resistance Develops egg mimicry ? Predator/Prey Arms Races Red Queen Hypothesis Example: Passiflora and Heliconius Egg Mimicry Heliconius eggs Passiflora egg mimic