Chapter 6: Species Interaction &
Community Ecology
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Species Interaction
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competition
predation
parasitism
symbiosis
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mutualism
amensalism
commensalism
herbivory
Competition
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limited resources seeked by multiple
species (density dependant)
organisms
– food
– shelter
– water
– mates
– sunlight
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Intraspecific: between different species
Interspecific: amongst individuals of the same
Intraspecific Competition
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may exclude another species, also known
also as competitive exclusion
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example: zebra mussel
may coexist without interfering, also known
as species coexistence.
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example: rat and mongoose in Hawaii
Predation
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structures the food web
influences community composition
helps determine the relative abundance of predator
and prey
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zebra muscle preys mostly on phytoplankton and some
zooplankton
these populations dropped 70% in Lake Erie and Hudson
River, but cyanobacteria are not predated so their
population increased.
populations of ducks, muskrats, crayfish, flounder, sturgeon
and eels prey on zebra muscle
Parasites
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exploits other organisms without killing them
immediatly, but may eventually cause death.
depends on the host for nourishment or other benefit
while harming the host.
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internal parasites: tapeworm, malaria, cholera, etc
external parasites: ticks, fleas, sea lamprey
Coevolution: host and parasite, as one changes, the
other evolves to keep the interaction between them
occuring
Herbivores
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eat plants
plants evolve defence mechanisms
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toxic or distasteful chemicals
volatile chemicals that atract predators
thorns
swelled stems where ants live and protect it
Symbiosis
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Mutualism: relationship in which 2 or more
species benefit from
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mycorrhizae
human digestive tract and bacteria
pollinating plants and bee
Symbiosis
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Amensalism: one is harmed while the other
is unaffected. This is difficult to observe.
Commensalism: one species benefits and
the other is unharmed.
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epiphytes growing on other plants
barnacles attached to whales
clown fish living in anemonies
Trophic Levels
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producers
consumers
detrivores
decomposers
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Producers
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autotrophs
first trophic level
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green plants, cyanobacteria, algae use
photosynthesis
chemosynthetic bacteria uses geothermal energy
Consumers
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primary consumers: consume producers
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secondary consumers: predators that prey
on primary consumers
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anchovy consumes plankton
tuna and comorant, both eat small fishes
tertiary consumers: higher lever of predator
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owls and hawks
Detrivores
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scavenge the waste products or dead bodies
of other community members
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condor or vultures
millipedes
beetles
Decomposers
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break down the material into its simple
compounds plants can use
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fungi
bacteria
Energy and Biomass
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some energy is lost as waste heat
every trophic level has some energy loss
next trophic level has less energy available
energy loss varies
pyramid
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Food Web
condor
killer whale
sea bird
seal
tuna
anchovie
plankton
Keystone Species
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indicator of the condition of the ecosystem as
a whole
usually found at top of food chain
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sea otter › feeds on urchins › feed on kelp
kelp maintains a balanced ecosystem
Disturbances
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removal of keystone species
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spread of invasive species
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kudzu
climate change
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sea otter eaten by killer whales
retrieve of a glacier
sudden events
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hurricanes
floods
avalanches
volcano eruption
Responce to Disturbances
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resistance: show no change even under
presence of a disturbance
resilience: may show a change, but later
returns to its original state
may show change and never return to its
original state
Succession
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changes in an ecosystem that follow a disturbance
Primary Succession follows
a disturbance so severe that
no vegetation or animal life
is left
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glacier
fires
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Secondary Succession
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follows a disturbance that not necessarily
destroyed all living things, some are left and
those are the building blocks of the future
community
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Mt. Saint Helen
Climax community remains in place with little
modification until the next disturbance occurs
Invasive Species
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non-native species that spreads widely becoming a
dominant species
can potentially alter the community
introduced by accident
limiting factors are removed or not present
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predator
competitor
parasites
weather change
Kudzu
ecological restoration
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Biomes
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major regional complex of similar communities
distinguished by a dominant plant
cover large geographic areas
largely in function of the climate
best indicators of an area's climate
aquatic systems also show biome patterns
altitude can vary biomes due to climate change, as
you climb mountains, the biomes change in
vegetation and animal species
Terrestrial Biomes
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temperate deciduous forest
temperate grassland
temperate rainforest
tropical rainforest
tropical dry forest
savanna
desert
tundra
boreal forest
chaparral
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Temperate Deciduous
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loses leafs
precipitation is spread evenly through the
year
relatively fertile soils
fewer species
oak, beeches, maples
central and southern Great Lakes
Temperate Grassland
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more extreme summer and winter
temperatures
limited amount of precipitation
grasses are supported more easily than trees
today mostly used for agriculture
bison, prairie dogs, antelope
Temperate Rainforest
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heavy rainfall
coniferous trees
interior of forest is shaded and damp
fertile soil
soil susceptible to erosion if trees are cut
down
north west of the US
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Tropical Rainforest
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high rainfall
dark and damp
lush vegetation
highly diverse communities
high number of different trees at low density
poor acidic soils, not proper for farming
closer to the equator: Central and S.America, Asia
uniform warmer temperatures year-round
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Tropical Dry Forest
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warm year-round but highly seasonal
precipitation
India, Africa, S.America, N. Australia
can be converted to agriculture
native plants adapted to the seasonal rains
growing during wet season and become
dormant during dry season.
Savanna
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grassland with occasional clusters of trees
Africa, S.America, Australia, India
distinctive rainy season
animals migrate according to rain
water holes formed by rain
Dessert
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driest biome, well under 25cm of rain/year
isolated storms months or years apart
vegetation depends on the rain amount
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Sahara: very little rain
Sonora: enough rain to sustain vegetation
temperature variation may be dramatic
anatomical and behavioral adaptations
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large ears to cool down
active at night
green trunk, leathery leaves
and spines
Tundra
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Russia, Scandinavia, Canada
extremely cold
lichens and scrubby vegetation, no trees
permanently frozen soil= permafrost
migrating birds are attracted to it in summer
polar bears and oxen are the few local
species
Boreal Forest
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also known as taiga
cooler dryer areas
long cold winters, short cool summers
few species of coniferous trees
poor soils, usually acidic
animals breed and eat during summer, some
hibernate during winter
Canada, Alaska, Russia and Scandinavia
Chaparral
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limited
evergreen shrubs, densely thicketed
highly seasonal
mild wet winters and dry summers
experience fires in summer
California, Mediterranean coast, Chile,
southern Australia
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Altitude Patterns similar to those created by Latitude
THE END
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