24.11.30: population ecology

cengage chapter 5: population ecology
Five main types of species interactions:
interspecific competition
predation
parasitism
mutualism
commensalismInterspecific competition: two species, niches overlap, compete for resources (e.g. humans and many animals)Resource partitioning: one resource is shared by species, but in different ways:
Predation: predator-prey (one always dies, the other survives)See also predator prey growth cyclesPredator strategies: speed (e.g. cheetah)
teamwork (e.g. lions)
camouflage (e.g. praying mantis)
chemical warfare (e.g. spiders)
Prey survival strategies:speed (gazelle)
senses (sight, sound, smell)
physical (shells, spines, thorns)
camouflage (arctic hare)
chemical warfare (octopus)
mimicry (looking like something else)
Coevolution: predator gets better, prey gets better, predator gets better...
bats use sound to find moths (echolocation)
moths evolve to hear the sounds, evade
bats change the frequency
moths evolve to create their own sounds, blocking the bats
bats evolve to listen for the moth soundsParasitism: One lives off of energy and nutrients from the host "it is bad manners for the parasite to kill the host" Mutualism: both benefit (birds eating bugs on cattle)
Commensalism: one benefits, the other does not care (orchids in trees)
Ecological succession:
Primary succession: from bare rock, no organic materials
Secondary succession: building blocks for live are there, have been removed (e.g. forest fire)
Different take on resistance and resilience:Resistance: "ecological intertia or persistence"
Resilience: ability to recover
Ecosystems have one or the other, not both:
Tropical rain forest: high diversity, high resistance, but when cleared cannot recover
Grasslands: low diversity, low resistance, but high resilience, organics are in the roots in a fire
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