Download Chapter 8: Community Ecology

II. The Living World (10-15%)
• 1. *Ecosystem Structure (Biological populations and communities;
ecological niches; interactions among species; keystone species;
species diversity and edge effects; major terrestrial and aquatic
biomes)
• 2. *Energy Flow (Photosynthesis and cellular respiration; food webs
and trophic levels; ecological pyramids)
• 3. *Ecosystem Diversity (Biodiversity; natural selection; evolution;
ecosystem services)
• 4. *Natural Ecosystem Change (Climate shifts; species movement;
ecological succession)
• 5. Natural Biogeochemical Cycles (Carbon, nitrogen, phosphorus,
sulfur, water, conservation of matter)
100
30
20
50
10
ft
m
Tropical
rain forest
Coniferous
forest
Deciduous
forest
Thorn
forest
Thorn
scrub
Tall-grass
prairie
Short-grass
prairie
Terrestrial Communities
Desert
scrub
Latitude Effects on Richness
1,000
Species Diversity
Species Diversity
200
100
0
90ºN
100
10
60
30
0
Latitude
(a) Ants
30ºS
60
80ºN
60
40
Latitude
(b) Breeding birds
20
0
MacArthur and Wilson
• Study done comparing small and large
island biodiversity.
• Conclusions:
– Small islands have less animals coming to it
because it is a small target to immigrate to.
– Smaller islands have higher extinction rates
because of fewer resources and habitats
– Islands closer to mainlands will have higher
immigration of animals.
Species
• Native: species that normally live in an area. In
Iowa: whitetail deer, squirrel, bass, etc.
• Non-native: AKA invasive or alien. Brought into
an area intentionally or accidentally. Can often
overtake native species. Asian beetle, water
milfoil, zebra mussel, etc.
• Indicator: species that will be affected first by
environmental change. Trout (temperature),
frogs, birds.
• Keystone: species that have an effect on a
large number of other species. (pollination,
predation, etc)
Why we love Kermit the Frog
• Amphibians are excellent indicator species.
• Why?
– Lifecycle puts it in contact with land and water
– Vulnerable to a wide variety of chemicals, radiation,
pollutants
• Frog species loss
–
–
–
–
Habitat loss
Pollution
Hunting (frog legs)
UV radiation
Number of individuals
© 2004 Brooks/Cole – Thomson Learning
Resource Partitioning
Species 1
Species 2
Hawks and
Owls =
same prey.
Region
of
niche overlap
Number of individuals
Resource use
Species 1
Species 2
Resource use
Hawks –
hunt by day
Owls – hunt
by night
Resource
Partitioning
Prey Defense Mechanisms
• Avoidance: Hedgehogs (rollup/spines),
lizards tails that break off, turtle (shell),
• Camouflage: coloring, patterns, etc to
help blend in. Deer, frogs, etc.
• Poison: Oleander plants, some frogs
• Foul smell/taste: Monarchs, skunks, etc.
• Warning color: bright color to show
poisonous nature.
• Mimicry: Look like a poisonous animal,
act like another (bull snake “rattling”)
Camouflage
Span worm
Poison/Warning Color
Poison dart frog
Camouflage
Wandering leaf insect
Mimicry
Viceroy butterfly
Foul smell
Bombardier beetle
Mimicry
io moth
Foul taste
monarch butterfly
Mimicry
snake caterpillar
Prey Defense Mechanisms
Relationships
• Predator-Prey: “eat or be eaten”
• Parasitism: one organism lives
off of another. Host is often weakened, but not
killed. Examples: tapeworms, wood ticks,
cowbird eggs.
• Mutualism: both species in relationship will
benefit. Example: clown fish/sea anemone.
• Commensalism: one organism benefits, the
other is not affected. Some doubt this exists as
“some effect” must occur. Example: seeds
traveling on animals
Review clip for visual
ECOLOGICAL
SUCCESSION
Changes in the biotic
characteristics in an
area over time.
Primary
Succession
Secondary
Succession
Two types of ecological succession
Primary succession: occurs on a surface where
no ecosystem existed before (no soil)
Secondary succession: occurs on a surface where
an ecosystem has previously existed but has been
disturbed (soil is present)
Primary Succession
• Starts with: barren rock (land) or rock bottom of
lake, river, stream. Examples: area after volcanic
eruption, glacier retreat.
• Pioneer species: usually lichen and moss.
Begins to break down rock to make soil.
• Early successional plants: annuals, low
growing, short lives.
• Midsuccessional plants: herbs, taller grasses,
shrubs.
• Late successional plants: mostly trees.
• Climax community (succession completed)
• View clip
Primary Succession
Exposed
Lichens
rocks and mosses
Small herbs
and shrubs
Heath mat
Jack pine,
black spruce,
and aspen
Balsam fir,
paper birch, and
white spruce
climax community
Time
Review soil formation
For example,
eastern U.S. climax species are
oak, hickory, maple
Succession in the boreal forest (for example in Canada) – climax
species are fir, spruce, hemlock
Secondary Succession
• Starts with: disaster or human activity
that destroys environment, but soil
remains.
• Follows same process as Primary
succession, but lengthy soil making
process gets to be “skipped”
• First to re-grow: small grasses,
plants then leads to larger
shrubs and trees.
Mature oak-hickory forest
Young pine forest
Annual
weeds
Perennial
weeds and
grasses
Shrubs
Time
Secondary succession
Ecological Succession can occur in
aquatic ecosystems
© 2003 John Wiley and Sons Publishers

Starts with: newly formed pond/lake
 Typically from glacial retreat
 Bottom is rocky.
Sediment is brought in by runoff, erosion.
 Plants able to grow on edges only.
 Plant growth, death, decay leads to
more nutrients.
 Normal eutrophication can lead to
wetland, then meadow.
 Succession would end with grassland or
meadow

Aquatic Succession
• Starts with: newly formed pond/lake
• Typically from glacial retreat
• Bottom is rocky.
• Sediment is brought in by runoff, erosion.
• Plants able to grow on edges only.
• Plant growth, death, decay leads to more
nutrients.
• Normal eutrophication can lead to wetland,
then meadow.
• Succession would end with grassland or
meadow
Aquatic Succession
Even in one location, the climax community
depends on many factors
Changes in Biota
© 2003 John Wiley and Sons Publishers
Changes in Abiotic Factors
© 2003 John Wiley and Sons Publishers
II. The Living World (10-15%)
• 1. *Ecosystem Structure (Biological populations and communities;
ecological niches; interactions among species; keystone species;
species diversity and edge effects; major terrestrial and aquatic
biomes)
• 2. *Energy Flow (Photosynthesis and cellular respiration; food webs
and trophic levels; ecological pyramids)
• 3. *Ecosystem Diversity (Biodiversity; natural selection; evolution;
ecosystem services)
• 4. *Natural Ecosystem Change (Climate shifts; species movement;
ecological succession)
• 5. Natural Biogeochemical Cycles (Carbon, nitrogen, phosphorus,
sulfur, water, conservation of matter)