Animal Interactions
Responses to the biotic environment
INTERSPECIFIC
AGGRESSIVECompetitionPredator-preyParasite-host
CO-OPERATIVEMutualismCommensalismAntibiosis
Competition
Individuals of different species vie for the same resource in an ecosystem (e.g. food or living space).
Gause’s principle – no two species with exactly identical niches can co-exist for long in the same place
competitive exclusion (one species outcompetes the other) OR
adaptive radiation (one species adapts to a different niche)
Predator-prey relationships
• Evolution physiological & behavioural adaptations • Predator becomes a more successful predator• Prey becomes better at escaping predation
Birds of prey have developed extremely good eyesight to spot prey from a distance
PREDATORS 1 – PREY 0
Foxes are fast and quick-witted
PREDATORS 2 – PREY 0
PREDATORS 3 – PREY 0
Lynx vs rabbit
Lions hunt co-operatively
PREDATORS 4 – PREY 0
PREDATORS 3 – PREY 100
Speed is very advantageous for prey animals........
Methods of getting food
Let the prey come to you• Traps• Webs• Bait• Ambush• Sieves
Methods of getting food
Move after the prey• speed• teamwork• swarms• tools• appendages
Parasite-host relationships MosquitoEctoparasite
• Endoparasite
Parasitoid wasp lays eggs on caterpillar
INTERSPECIFIC
AGGRESSIVECompetitionPredator-preyParasite-host
CO-OPERATIVEMutualismCommensalismAntibiosis
Mutualism
• Bees pollinate flowers
Mutualism
• Tickbirds eat ticks
Commensalism
• Remoras attach themselves to sharks and hitch a ride, also eat leftovers
Antibiosis
• Large trees shading out smaller undergrowth• Animals trampling down the homes of smaller
animals• Human sewage disposal
“Go outside to do your business”
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