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Chapter 2
Biological Communities
Close, long term interactions –
determine the nature of
communities
Habitat – where an organism
lives
 Niche - the role of a species in an
ecosystem
 how the organism affects energy
flow within the ecosystem
 Niche is influenced by
several variables –
temperature it prefers, the
time of year it breeds, what it
likes to eat, and where it
finds its food
Types of community interactions
Predation
 Predators and prey develop
adaptations for survival
Prey adaptations – mimicry,
camouflage or poisonous
Plants also avoid being
eaten
Competition
 Use of limited resources by 2 or more
species – niche overlap - Red Maples
Competition limits how species
use resources
Predation and Competition
 predation reduces the effects of
competition.
 Predation increases biodiversity
 Biodiversity- types and numbers of
organisms in an ecosystem
 The larger the area, the more species
(usually)
3 Types of Symbiotic
Relationships
 Close relationship when 2 or more
species live together
 Parasitism
 Mutualism
 Commensalism
Parasitism
 Parasites harm the host
 Ecto – outside
 Endo – inside
 Defenses against
parasites?
 Parasite adaptations for
survival?
 Mutualism – both organisms
benefit, ex –ants & aphids
 Commensalism – 1 benefits, the
other not affected