BIO120H1 Lecture Notes - Lecture 10: Trophic Cascade, Goldenrod, Insecticide
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BIO120H1 Full Course Notes
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Primary producers = plants: make their own food through sunlight. Primary consumers = herbivores: one step removed, eat plants. Secondary consumers = carnivores who eat herbivores: detritivores = eat dead organic matter. Tertiary consumers = carnivores who eat secondary consumers: decomposers, break down dead organisms. Trophic connections among species can be analyzed as interaction webs with network properties like (cid:862)(cid:272)o(cid:374)(cid:374)e(cid:272)ta(cid:374)(cid:272)e(cid:863: meaningful if have good data sets. Skeptical that ecologists can learn a lot from this system: more important, trophic relations can determine community structure in ways that can be investigated by removal experiments, most reliable and valuable. Interaction strengths are assessed by removal experiments: replicate flats of vegetation, one part sprayed with insecticide, one left without. Sprayed with insecticide: monoculture of goldenrod: more productive in plant material, biodiversity (palnt diversity) low, goldenrod beetles suppressed - insecticide knocked down populations of specialist beetle that eats golden rod, most insects are specialized in host plant. Left alone: beetles abundant, high plants diversity.
