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lecture note

Course Code
Ingrid L.Stefanovic

of 2
L09- BIO 120
Trophic : where nutrition comes from.
Trophic levels:
Primary producers = plants
Primary consumers = herbivores
Secondary consumers = carnivores who eat herbivores
Tertiary consumers = carnivores who eat secondary consumers (carnivores)
Detritivores = eat dead organic matter
Addition Experiments- adding a species.
Trophic cascades paper(Smith & Slobodkin) the world is green because
carnivores keep down herbivores so herbivores dont limit plant growth.
Small scattered island some plants which are preyed upon by beetles.
Beetles are eaten by lizards and spiders.
Easie to be a carnivore consuming tissue much like own tissues less
chemical changes have to made to make use of the food they are consuming.
Plants have to go through more chemical processes to make food edible
Much biodiversity resides in plants & insects
Milweed: some animlas can eat it because the “ milky liquid is poisonous to
them, but there are some specialized insects (catepillar) to eat it
Monarch butterflies: colored brightly to warn predator to not eat them
Vincristine: helps in fighting breast cancer, strychnine, rat poison
Grasslands- grazers (larger animals like deer)
Forests- insects
Pregnant sheep eats VERATRUM –birth defects (dosages f this plant given to
skin cancer)
Pika: in summer eat a different plant, and in winter eat a different kind.
Why this seasonal progression? Pikas manipulate toxin levels and preserve
winter food.