Class Notes (1,100,000)
CA (650,000)
UTSG (50,000)
BIO (2,000)
BIO120H1 (1,000)
Lecture 10

BIO120H1 Lecture Notes - Lecture 10: Detritivore, Lignin, Autotroph

Course Code
Jon Abbatt

This preview shows page 1. to view the full 4 pages of the document.
Lecture 10: Tropic relationships in communities
Trophic Level
Primary produced (autotroph): self-feeding , plants
Primary consumer: consumers of primary producers; herbivores from ants to zebras
Secondary consumers: carnivores who eats herbivores
Tertiary consumers: carnivores who eat secondary consumers
Detritivores: eat dead organic matters
Food webs (Functional web)
Emphasizes the influence of populations on growth rates in other populations.
Can only be revealed by experiments
Control experiment
Beetles abundant
High plant diversity
Insecticide treatment
Beetles suppressed
Low plant diversity
Beetle here are Keystone consumers because when
they are removed, the edifice of the community tumbles
Interaction strengths are assessed by removal experiments.
Trophic Cascades
Hairston, Smith & Slobodkin
Suggested that the earth is green because carnivores depress the populations of
herbivores that would otherwise consume most of the vegetation.
Indirect effect: one trophic level exerts influences on a send by affecting a third.
o Cascades involves effect that alternate across trophic levels.
Top-down control:
when higher trophic levels
determine the sizes of the
trophic levels below them.
Bottom-up control:
when the size of a trophic
level is determined by the
rate of production of its food
Experiment by Knight et al.
You're Reading a Preview

Unlock to view full version