22. Predation, Herbivory & Avoidance Flashcards
Exploitation
Positive for A
Negative for B
How do species prevent going extinct from predation
- Defense: don’t get eaten
- Refugia/refuges: seek refuge from predators
Defense: Fight back
-mobbing or attacking predators with chemical or mechanical means
-learning experience (not necessarily death) for predator
Aposematic denfense
Don’t eat me— I’m not tasty!
Bright, conspicuous colouration, toxic or distasteful species
Müllerian mimicry
Mimic warning signals among different poisonous species
Eg wasps, hornets, bees all sting. Once stung a predator probably won’t try to eat another one (learning)
Batesian mimicry
Only look poisonous, non-toxic species resemble a toxic one
Camouflage
Can’t eat me if you can’t see me!
Mostly visual, sometimes olfactory
Spatial refugia
Hide where predators can’t find you
Costs energy and hampers foraging opportunities, but better than dying
Protection in numbers
Have populations so large, individual risk of being eaten is minimized
Gause’s predation experiments
Putting predator and prey together: did not result in fluctuations suggested in Lotka-Volterra predator—prey model, both went extinct
Creating refugia: prey hid so effectively predator dies
Create immigration: restocking prey, oscillations occur as predicted by L-V model
Huffaker’s Experiment
Predator mite feeding on prey mite
Provided food for prey, movement barriers for predators, dispersal aids for prey
Oscillations without restocking
Metapopulation rescue
Individuals from largers populations can immigrate to rescue smaller populations
Size refugia
Be too large to eat
Pro— cant be eaten
Con— takes a lot of energy to maintain size
Plant resistance to herbivores
Resistance: less likely to be eaten
Tolerance: reduce harm from being eaten
Constitutive defenses
Produced continuously regardless of what happens to the plant
Induced defenses
Concentrations of a defensive chemical or defensive morphology increase rapidly in response to damage by herbivores
Constitutive chemical resistance
Toxins
Digestion reducing compounds
Why are fruits not avoided
Eating them doesnt hurt plant, increases reproduction by seed dispersal
Why are there toxic fruits
Not ripe yet
Reduce risk of seed digestion (laxative, digestion reducing properties)
Facilitate seed dispersal by fugivores (animals that disperse seeds by eatinf fruit)
Why don’t plants have warning colouration?
Plants need to be green bc of chlorophyll
Why are flowers selected for?
Colours attract pollinators, not related to herbivory
Overcompensation
Increased plant growth following herbivory compared to plants that did not experience herbivory
What causes overcompensatikn
Light grazing, feces, grazing early in summer
