Transcript INTRO TO ECOLOGY

Community Ecology
CH 20
Species Interactions
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Predation
Parasitism
Competition
Mutualism
Commensalism
Predation
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Helps shape community
Predator: eats another
Prey: gets eaten
Natural selection favors
adaptations that help predator
efficiency and prey avoidance
mechanisms
Predator
avoidance
Camouflage
Chemical warfare
Warning coloration
Mimicry
Deceptive looks
Deceptive behavior
Antipredator defense
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Mimicry: organism looks like a
poisonous one (Monarch &
Viceroy butterfly)
What can a plant do?
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Deterrents to
herbivores: spines,
thorns, thick leaves,
serrated edges,
secondary
compounds (poison
etc.)
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Symbiotic Relationships:
1. Parasitism
+/Harms one (host) & helps the
other (parasite)
Usually doesn’t kill host
Ectoparasite: external (tick,
leech, mosquito)
Endoparasite: internal
(tapeworm, malaria parasite)
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Symbiotic Relationships:
2. Mutualism
+/+
Both species benefit from
each other
Pollination - bird gets
food, plant gets
pollination service
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Symbiotic Relationships:
3. Commensalism
+/0
One species benefits and the
other is not affected (or the 2nd
benefit hasn’t been discovered
yet)
Ø
Human Our
eyelashes are home
to tiny mites
that feast on oil
secretions and dead
skin. Without harming
us, up to 20 mites
may be living in one
eyelash follicle.
Commensalism
Ø Organism is not affected +
+
Organism benefits
Demodicids Eyelash
mites find all they need
to survive in the tiny
follicles
of eyelashes. Magnified
here 225 times, these
creatures measure 0.4
mm in length and can be
seen only with a
microscope.
Competition
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Results from fundamental niche
overlap
Competitive exclusion principle:
one species eliminates the
other (one uses resources
better and has a reproductive
advantage)
Competition
Character Displacement
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Natural Selection favors
differences in competitors
Niche overlap may lead to
differences
Darwin’s finches (beak size is
different when there is
competition on the island)
Resource Partitioning
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When species use the same
resources, they use only part of
them
Different warblers feeding in
different parts of a tree
Reduces competition
Resource Partitioning
Properties of Communities
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Species richness: The number of different
species a community contains
Species Evenness: relative abundance of
each species
Species diversity: Relationship between
richness & evenness
Patterns of richness
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Varies w/ latitude - closer to
equator = more species
• Why? Less disturbed b/c ice age
didn’t affect them
• more stable climate
• more plants = more food
Species Area Effect
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Larger areas usually more
diverse, more diversity of
habitats
Humans destroy habitats and
diversity goes with them
Succession
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Gradual, sequential regrowth of species in
an area
Types of Succession
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Primary: The area has never had
life - new island, bare rock…is 1st
(or primary time) for life to succeed
Secondary: The existing
community was disturbed - fire,
logging, human activity (gets a 2nd
chance to succeed)
Pioneer species - first to arrive,
small, fast-growing, good disperser
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Primary Succession
Very slow
Have to create the soil
Proceeds from lichens & mosses to
climax community
Takes hundreds of years
Each stage paves the way for the next
Secondary Succession
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Varies where it starts,
depending on level of
disturbance
May take 100 years
Short-lived grass, long-lived
grass, shrubs, trees
Fire Succession
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Needed for:
– Reproduction
– Clearing out
competitors
Complexity of Succession
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Climax community - stable end
point
• There may be no such thing
• Too complex to predict
Major Biomes = CH 21
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Terrestrial (land)
ecosystems
• Tundra
• Tropical forest
• Temperate forest
• Taiga
• Temperate grassland
• Savanna
• Chaparral
• Desert
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Tundra
Major Biomes
• Cold
• Permafrost under the
surface of the ground
• Lacks trees
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Forests
• Tropical:
• abundant rainfall,
stable & warm
temps., high
species diversity
• Temperate
• Coniferous (conebearing) or
deciduous (lose
their leaves) trees
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Taiga
Major Biomes
• Cold, warmer than tundra
• More precip. Than tundra
• Mostly coniferous forests
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Grasslands
• Tropical aka Savanna:
• Alternating wet/dry seasons
• Warm year-round
• Herds of grazing animals
• Temperate
• Cold winter & hot summer
• Grasses
• Herds of grazing animals
Major Biomes
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Deserts
• Less than 25 cm (10 inches) rain/yr
• Inhabitants have adaptations to
conserving water
• Nocturnal
• Light color
• Leaves  spines
Ocean Zones
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Photic zone: shallow enough to receive
sunlight (photosyn.) unlike aphotic zone
Zones determined by location
Intertidal
• Btwn high and low tide
• Animals must tolerate drying out & wave action
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Ocean Zones
Neritic zone:
• Receives nutrients from bottom of ocean
(upwelling) and from land
• Richest zone in # of species & # of individuals
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Ocean Zones
Oceanic zone:
• Far from land
• Productivity limited by lack of nutrients
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Estuaries:
Ocean Zones
• Rivers flow into ocean
• Very productive  nutrients from land
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Freshwater
Zones
Lakes & Ponds:
• Oligotrophic: low nutrients,
clear water
• Eutrophic: high nutrients,
cloudy water
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Freshwater
Zones
Rivers & Streams
• Flow down an elevation gradient
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Freshwater Wetlands
• Marshs & swamps
• Very “productive”
• Covered w/ water at least part of the year
SCAVENGER HUNT
Animals = Ch 35, 36, 40
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Arthropod-invertebrate with
exoskeleton, jointed
appendages and segmented
body
Amphibian-frogs, toads,
salamanders; metamorphose
from juvenile water-breather to
adult air-breather
Mollusk-snails, slugs, squid,
octopus; mantle used for
breathing and excretion
Plants = Ch 28-30
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Dicot plant-2 seed flowering plant
Monocot plant-1 seed flowering plant
Alga- singular for algae; autotrophic,
photosynthetic; seaweed
Gymnosperm
Angiosperm
Bryophyte
Fern
Sporophyte and gametophyte
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Renewable
resource= water,
oxygen, timber,
fruits, meat, wind,
solar power
Nonrenewable
resource= coal, oil,
gas, copper
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Habitat
fragmentation=
when native is
cleared for human
activities for
agriculture, rural or
urbanization
Humans & the
Environment = CH 22
This is Fresh Kills Landfill in NY…..it covers 8
square miles and receives 34 million pounds of
garbage each DAY!
Earth’s Layers
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Biosphere includes:
• Geosphere: rock/land – important to
biogeochemical cycles
• Hydrosphere: water
• Oceans cover 70% of surface
• Freshwater <3% (mostly inaccessible)
• Atmosphere: mixture of gases (air)
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Atmosphere includes:
• Greenhouse gas layer trap heat on Earth – in
“troposphere”
• Ozone Layer  protects Earth from harmful UV
radiation – in “stratosphere”
• Ozone means “to smell”
Ozone Thinning
•O3 layer in upper atmosphere – helpful
•Ozone layer lies 11-16 miles above Earth’s
surface
•Screens harmful UV radiation that causes skin
cancer…absorbs 99% of radiation
•CFC’s (chloroflouorocarbons) chemicals that
break down ozone come from A/C, aerosol cans,
refrigerators etc.
Ozone Thinning
•CFC’s
banned in 1995
•1 CFC may destroy 100,000
ozone molecules
•Biggest hole over Antarctica
•May take 50-100 yrs to rebuild
•@ ground level, ozone irritates
nasal passages, throat, lungs
Global Warming
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CO2 and water vapor trap heat = greenhouse
effect
CO2 does trap more solar energy
Increased CO2 from burning fossil fuels (coal,
oil, natural gas)
Increasing CO2 levels correlate w/ increase in
temp.
Earth has raised 1° F since 1860; May raise 3-8°
F by 2100 = melt polar ice caps (hottest year on
record is 1998 then 2003)
Global Warming
•Implications
-Shift agricultural regions
-Disrupt aquatic &
terrestrial ecosystems
-Rising sea levels
-More extreme weather
events
Greenhouse Effect
-Gases trap heat near planet’s surface just as glass
panes found in a greenhouse
Greenhouse Effect
-4 gases: carbon dioxide, CFC’s, methane,
nitrous oxide
-Every 1% drop in ozone will lead to 6%
increase in skin cancer and will also
reduce # of certain marine algae = fewer
producers 
Global Warming Facts
1. “Global warming is caused by
depletion of the ozone layer”—
THIS IS NOT TRUE---DON’T SAY!
2. W/OUT GASES, SCIENTISTS
ESTIMATE THE EARTH’S AVG
TEMP TO BE 0 DEGREES
3. Economics of Global Warming:
-What happens if we continue to have
storms and earthquakes?
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More Pollution Issues
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Smog
Acid Precipitation
• Organisms are adapted to
specific pH-tied to H20 cycle
• Pollutants in air can change
the pH and lead to problems
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Land & water pollution
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Sewage
Industries
Burning fossil fuels
Biological magnification
• Chemicals move through the food
chain becoming more concentrated
the higher up you are
• Ex: DDT, mercury
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Removing DDT in US has helped save bald eagle pop
Dichlorodiphenyltrichloroethane = P ESTICIDE
Ecosystem Disruption
•Humans simplify ecosystems 
• ex: farmland, urban areas
•Extinction
•20% of species may be extinct in next 50
yrs
•Biggest threat’s:habitat destruction,
invasive species, overharvesting, hunting
•1/2 of rainforests may be gone by 2020
Keystone Species
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One who affects many
others
Maintains richness in
a community
If it disappears, the
stability comes apart
• Otters/sea
urchins/giant kelp
Community Stability
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How does the community
respond to disturbance
More species = greater stability
Human Resource Use
•Humans use 10 – 55% of
Earth’s primary productivity
•Ecological Footprint:
analysis of your resource
use; analyze people’s use of
food/natural resources
•Sustainability: meet the
needs of a population
indefinitely—need to close
the gap b/n renewable and
nonrenewable resources
Human Resource Use
-Need to work on:
-energy production
-transportation
-agriculture
-housing
-waste disposal
-slow human population growth
-decrease the consumption of
resources
Environmental Solutions
•Conservation: maintain & protect
natural areas
•Restoration: trying to return an area to
natural conditions
•Ex: drained wetlands
•Bioindicators: use as early warning
system b/c are especially sensitive to
ecological changes
•Ex: Rainbow trout, mussels, frogs
and their mating calls
Saving Biodiversity
•Debt for nature swap: Money is given to
developing countries to save their
biodiversity (instead of converting it to
farmland etc.)
•Ecotourism: helps preserve nature and
educate people
•Laws:
•1970 = Environmental Protection Agency
created (EPA)
•1973 = Endangered Species Act
•1990 = Clean Air Act
Restoration Case Study = p 451
•Florida Everglades
•Army Corps of Engineers diverted water
from Lake Okeechobee for cities and
agriculture – previously would go to
Kissimmee River to oceans making
extensive wetlands
•Devastated the natural ecosystem –
pesticide and fertilizer runoff, heavy
metals, reduction in water = increase
salinity
•Army corps responsible for long-term
restoration, most ambitious in U.S.
History
Restoration Case Study = p 447
-Before 1870, whooping cranes
migrated b/n Canada and Gulf Coast
-Hunters killed whoopers for feathers
and drained marshes for land
-in 1937, only 15 whoopers left so US
govt regulated hunting of birds and
started a captive breeding program
-negative impacts of captivity:
-don’t know how to migrate
or do courtship dance
Captive Breeding Programs
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Boost #’s
Species live somewhere else
until habitat improves
Inbreeding is prevented
Learn immense amount of
detail about population