Presentation on theme: "1 How does an animal avoid being eaten?. 2 5/27/08: Behavioral adaptations for survival Lecture objectives: 1.Be able to generate hypotheses and predictions."— Presentation transcript:
2 5/27/08: Behavioral adaptations for survival Lecture objectives: 1.Be able to generate hypotheses and predictions for the adaptive value of a potential antipredator strategy 2.Recognize the antipredator benefits that might arise from living in groups
6 Minimize risk of detection 2. Crypsis (morphology & behavior) African assassin bug Hypothesis: Assassin bug “backpacking” is an adaptive antipredator behavior Predictions?
7 Minimize risk of detection 2. Crypsis (morphology & behavior) Hypothesis: Catocala relicta (moth) perching behavior is an adaptive antipredator behavior Predictions: 1. moth background choice: 2. bird predation:
8 Minimize risk of attack 1. Hypothesis: Anolis lizard push-ups are honest signal of health Predictions? **Human female self-defense strategies** “Crime victims are frequently chosen because they are easy targets. Criminals prey on the weak or unsuspecting and usually avoid people who are aware of what’s going on and might put up a fight. When out in public, look people in the eye, keep your head up and walk with confidence.” -Realistic Female Self Defense Company
9 Minimize risk of attack 2. Individuals or groups? Mobbing behavior: finches vs. hawk Stinging insects Sawfly larvae (with eucalyptus oils)
11 Minimize risk of attack 4. b) Amazon caterpillar & Mexican vine snake Mimic: a) an aposematic species (Batesian mimicry) b) a predator of your predator c) your predator Model (acoustical) Mimic: burrowing owl a)
12 Minimize risk of attack 4. Deceive predator (mimicry) Mimic: a) an aposematic species (Batesian mimicry) b) a predator of your predator c) your predator c) Tephritid fly and jumping spider Hypothesis: Tephritid fly wing-waving is an adaptive antipredator behavior Predictions Tephritid fly House fly
13 Minimize risk of (lethal) capture 1. Why might an ability to vastly outrun a predator be unlikely to evolve? Flight muscle ratio
14 Minimize risk of (lethal) capture 2. hairstreak butterflyDesert gecko Hypothesis: Butterfly false heads help prey survive capture controlFalse head % escaping30% 10%
15 Minimize risk of (lethal) capture 3. Adelie penguins vs. leopard seal
16 Minimize risk of (lethal) capture 3. Aggregate to reduce probability of capture (dilution effect) Is there safety in numbers? The effect of cattle herding on biting risk from tsetse flies.
17 Minimize risk of (lethal) capture 4. A group of individuals whose members use others as living shields against predators Center of colony Edge of colony Away from colony Position of nestSnails/nestChases/fish/hr.
18 Minimize risk of (lethal) capture 5. 1 40 20 0 2-1011-50>50 Mean reaction distance (m)
19 Why do gazelles exhibit stotting behavior? H1. Alarm signal: Warns conspecifics that predator is near. H2. Confusion effect: Stotting individuals in a fleeing herd might confuse/distract a predator so that it can’t focus on one prey H3. Pursuit deterrence: Stotting advertises that the individual is in good health and is unlikely to be captured Stot when alone Stot when in groups Show rump to predator Show rump to gazelles PredictionAlarm signalConfusionDeter pursuit