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Community Ecology
Packet #32
Chapter 14
Review & Introduction
 Community
 Assemblage of
populations, of different
species, that live and
interact in the same place
at the same time
 Community Ecology
 Description and analysis of
patterns and processes
within the community
Introduction II
 Communities are difficult
to study
 Large number of
organisms Communities
vary in size
Communities
Difficult to Study
 Lack precise boundaries
 Rarely completely isolated
 Within a community, no
species exists
independently of other
species.
Large numbers
Varying size
No precise
boundaries
Rarely isolated
No independent
species
Community Ecology
Community Structure & Functioning
Niche [nich]
 The function or position of
an organism or population
within an ecological
community.
 The particular area within a
habitat occupied by an
organism.
 HW
 What is a habitat?
Niche [nich] II
 There are factors that impact/restrict the ecological
niche of a species within a habitat.
 Limiting resources
 Abiotic factors
 Soil composition
 Climatic extremes
 Any environmental resource that is scarce or
unfavorable
 Biotic factors
Competition
 Intraspecific

Competition between
members of same species
 Interspecific

Competition between
members of different species
 Competition between two
species with overlapping
niches may lead to
competition exclusion

Results in the exclusion of
one species due to
interspecific competition.
Natural Selection
 Natural selection shapes the body forms and behaviors of both
predator and prey


Pursuit and ambush
Chemical protection

Plant defense
 Varied defense adaptations of animals to avoid predators


Fleeing
Hiding




Warning colors
Batesian mimicry
 Resemblance of a harmless organism to a harmful or unpalatable
organism
Mullerian mimicry
 Similar morphology of a group of harmful or unpalatable organism
 Monarch & Viceroy butterflies
Living in large groups
Community Ecology
Defense Mechanisms
Defense Mechanisms
Hiding
 Use of warning colors
 Aposmatic Colors
 A warning coloration
such as a 'striking' color
pattern designed to
attract attention and to
warn predators away.
Defense
Mechanisms
Hiding
Use of Warning
Colors
Batesian
Mimicry
Mullerian
Mimicry
Defense Mechanisms
Hiding
 Batesian mimicry
 Resemblance of a harmless
organism to a harmful or
unpalatable organism
Defense
Mechanisms
Hiding
Use of Warning
Colors
Batesian
Mimicry
Mullerian
Mimicry
Defense Mechanisms
Hiding
 Mullerian mimicry
Defense
Mechanisms
 Similar morphology of a
group of harmful or
unpalatable organism
 Monarch & Viceroy
butterflies
Hiding
Use of Warning
Colors
Batesian
Mimicry
Mullerian
Mimicry
Community Ecology
Relationships within Communities
Symbiosis
 Any intimate relationship
or association between
members of two or more
species
 Greek sym = together
 Greek bios = life
Symbiosis
Intimate
relationship b/t
two or more
species.
Mutalism
Commensalism
Parasitism
Types of Symbiosis I
 Mutualism
 Benefits are shared
 Nitrogen fixing bacteria
& legumes
 Zooxanthellae and reefbuilding coral
 Mycorrhizae facilitate
mutalistic relationships
between fungi and the
roots of a wide variety
of plants
Types of Symbiosis II
 Commensalism
 Taking without harm
 Epiphytes living on
tropical tress benefit
from the habitat of the
host, but the host is not
harmed or benefited.
Types of Symbiosis III
 Parasitism
 Taking at another’s
expense
 Parasite benefits while
host is harmed
 Well adapted parasite
does not kill the host
 Parasite that causes the
death of the host is a
pathogen
Keystone Species
 Affect the character of the community
 Have a great effect on other species in the
community
 Commonly are the top predators
 Dominant species influence the community as a
result of their greater size or abundance
 Trees are the dominant species in forests because they
change the local environment
 Coral, an animal, in coral reefs
Community Ecology
Community Development
Community Development—
Succession
 How do communities
develop?
 The most studied and
natural methods is known
as succession.
Succession
One species
replaced by
another
Primary
Succession
Secondary
Succession
Succession
 Process of community
development over time,
with one species being
replaced by another
Succession II
 Primary Succession
 Occurs when a community
develops in a “lifeless”
environment
 Occurs on bare rock
when rock is eventually
transformed into soil
 Occurs on newly
formed volcanic larva
and recently glaciated
rock
Succession III
 Secondary Succession
 Occurs when a community
develops where a previous
community existed
 Occurs where soil already
exists
 Areas denuded or
modified by fire or
agriculture
 Abandoned farmland
 Keep in mind that
disturbances impact
succession
Review
Review
 Students are encouraged to place their own
questions and charts on the following slides.