Download Community Interactions and Ecosystems Diversity Ecological Niche

Community
Interactions and
Ecosystems
Diversity
• The variety of different kinds of
organisms that make up a community.
Species richness:
Kinds of species.
Relative abundance:
Chapters 27-28
Ecological Niche
Total of a species’ use of the biotic and
abiotic resources in its environment.
– the way an organism
makes a living
– where it lives
– the habitat
– what it eats
– interactions with other
organisms
• No two species ever
occupy the same
ecological niche.
How many of each
species.
Competition
• Occurs whenever two organisms attempt to use the
same, limited resources
• The more the ecological niches of two species
overlap, the greater the amount of competition
between them.
!Competitive exclusion
!Resource partitioning
Competitive Exclusion
If two species
with the same niche
are placed together
and forced to
compete, inevitably
one will out
compete the other.
Invasive Species
• Violate the “checks and balances”
that keep native populations under
control.
– Japanese kudzu vine was
introduced in the 1920s to control
erosion.
– South American water hyacinth
was introduced as an ornamental
plant.
– Purple loosestrife was introduced
as an ornamental plant in the early
1800s.
Invasive Species
– Zebra mussels from
the Mediterranean
clogged water pipes,
cover crayfish, and
infest waters from
the Great Lakes to
New Orleans.
Resource Partitioning
• When two species with similar requirements
coexist, each typically occupies a smaller
niche than either would by itself.
Occurs when the
coevolution of two
species involves
extensive, but not
total, niche overlap.
Community Interactions
• Competition
• Predation
Predator and Prey
• To survive, predators must feed and prey
must avoid becoming food.
• As prey become more difficult to catch,
predators become more adept at hunting.
• Parasitism
• Mutualism
Coevolution
• Two interacting species act as
agents of natural selection on one
another over evolutionary time.
Predators adapt better
ways to get prey.
Prey adapt better ways
to escape predators.
Predator and Prey
• Bats find and locate prey
by echolocation, emitting
high-frequency sound and
analyzing the return
echoes.
• Certain moths have evolved simple ears that
are sensitive to the frequency used by bats.
• Moths fly erratically when they hear a bat
nearby.
• Bats have evolved to change the frequency of
their sound pulses.
Predator and Prey
Camouflage as Disguise
Camouflaged by blending in.
• To evade predators and
better catch prey,
organisms have evolved
several mechanisms:
–
–
–
–
Camouflage
Warning Coloration
Mimicry
Chemical Warfare
Camouflage as Disguise
Camouflage as Disguise
Camouflaged by blending in.
Camouflaged by resembling a specific object.
Camouflage as Disguise
Camouflage as Disguise
Camouflaged by resembling a specific object.
Camouflaged by resembling a specific object.
Camouflage as Disguise
Camouflage as Disguise
Camouflaged by resembling a specific object.
Camouflage assisting predators.
Camouflage as Disguise
Warning Coloration
Camouflage assisting predators.
• Use of bright coloration to advertise
distastefulness or toxicity.
Warning Coloration
Mimicry
• Use of bright coloration to advertise
distastefulness or toxicity.
• Evolving the coloration of another species.
– Müllerian mimicry: mimicry among different
distasteful species.
Mimicry
Mimicry
• Evolving the coloration of another species.
• Evolving the coloration of another species.
– Batesian mimicry: harmless species resembling
poisonous ones.
– Batesian mimicry: harmless species resembling
poisonous ones.
Mimicry
Mimicry
• Evolving the coloration of another species.
• Evolving the coloration of another species.
– Startle coloration:
evolving patterns of
color that closely
resemble the eyes
of a much larger,
often dangerous,
organism.
– Startle coloration:
evolving patterns of
color that closely
resemble the eyes
of a much larger,
often dangerous,
organism.
Mimicry
• Evolving the coloration of another species.
– A prey mimicking its predator.
Chemical
Warfare
• Production of
toxins or venom
for attack and
defense.
Chemical Warfare
• Production of toxins or venom for attack
and defense.
Symbiosis
• “Living Together”
• The close interaction between organisms
of different species for an extended time.
Parasitism
Mutualism
Commensalisms
Parasitism
• Parasites live in or on their prey (their
host), usually harming or weakening
them but not immediately killing them.
Mutualism
• An interaction between two species that
benefits both.
Lichen: algae and fungus
Algae provides food
through photosynthesis.
Fungus provides
protection and support.
Mutualism
• An interaction between two species that
benefits both.
Mutualism
• An interaction between two species that
benefits both.
Sea anemones and Clownfish
Acacia and Ants
Clownfish cleans the
anemone and drives away
predatory fish.
Acacia plants provide
food capsules and shelter.
Anemone provides
protection from predators.
Ants prevent other insects
from eating the plant, and
keeps undergrowth low.
Sea Otters:
a Keystone
Species
Keystone Species
• Play a major role in
determining
community structure.
• Sea otters eat
fish and small
invertebrates,
keeping their populations in check.
• Removal of sea otters from an ecosystem
resulted in an increase in sea urchin populations
and the destruction of kelp beds.
• Kelp forests create a habitat for a variety of
marine organisms.
– Usually a role that is
out of proportion to
its abundance in the
community.
– Removal of the
keystone species
would dramatically
alter the community.
Sea Otters:
Sea Otters:
a Keystone
Species
a Keystone
Species
Amichtka Island,
Rat Island group
Large population
of Sea Otters
Shemya Island,
Near Island group
No Sea Otters
Amichtka Island,
Rat Island group
Shemya Island,
Near Island group
Energy Flow Through
Communities
• Main Source of Energy: Sun
• Producers: Plants and algae
Energy Flow
Through
Communities
– Autotrophs, “self feeders”,
produce their own food.
• Consumers: All others
– Heterotrophs, “other feeders”
acquire energy and nutrients
by consuming other
organisms.
Energy Flow Through Communities
Energy Flow Through Communities
The Carbon Cycle
Nutrient Cycling
Volcanoes
• Nutrient Cycles, or biogeochemical cycles,
describe the pathways of substance as they
move through ecosystems.
Atmosphere
Biosphere
– Reservoirs are the ultimate sources and storage
sites of nutrients.
Oceans
Soils
Oil
Major Reservoirs
CO2 and Greenhouse Gasses
The Carbon Cycle
Volcanoes
Atmosphere
Volcanoes
Atmosphere
Oceans
Soils
Oceans
Soils
Oil
Movement through Reservoirs
Sinks
Sinks
Sources
Biosphere
Sources
Biosphere
heat
Oil
Ecosystem in Equilibrium
Anthropogenic: Changes caused by humans.
CO2 and Greenhouse Gasses
Volcanoes
Volcanoes
Atmosphere
Biosphere
Atmosphere
heat
Biosphere
Anthropogenic
Anthropogenic
Oceans
Soils
Human Perturbations change the Equilibrium
Global Climate Change
Oceans
Soils
Human Perturbations change the Equilibrium
Global Climate Change
• Caused by the burning of fossil fuels in
power plants, factories, and cars.
– 80-85% of CO2 is due to burning of fossil fuels
– 15-20% of CO2 is due to deforestation
• Before 1850: 280 ppm CO2
• Currently: 392 ppm CO2
– 40% increase
– Increase of ~2 ppm/yr
Global Climate Change
• The increase in greenhouse
gasses thickens the
atmosphere preventing
heat from escaping.
– CO2, CO, CH4, N2O, CFCs,
etc.
• The greenhouse effect is
the heating up of the planet
caused by greenhouse
gasses trapping solar
radiation.
Ruddiman, 2001. “Earth’s Climate Change” http://bcs.whfreeman.com/ruddiman/
How to Study Climate Change?
Natural records
are available to
scientists to study
temperatures, CO2
concentrations,
rainfall, acid
precipitation, etc.
Ruddiman, 2001. “Earth’s Climate Change” http://bcs.whfreeman.com/ruddiman/
Global
Climate Change
The climate shows
natural fluctuations
in CH4 and CO2,
but the rates of
change are much
faster today than in
geologic history.
Ruddiman, 2001. “Earth’s Climate Change” http://bcs.whfreeman.com/ruddiman/
Global Climate Chage: Now
Global Climate Change
1904
Global
Climate
Change:
Actual Effects
2004
• Ice is melting.
• Sea levels are
rising.
Intergovernmental Panel on Climate Change
http://www.ipcc-wg2.org/
Global
Climate Change:
Actual Effects
Global Climate Change:
Actual Effects
• Ice is melting.
Polar Bears depend
on Antarctic sea ice
for hunting and
survival.
Ruddiman, 2001. “Earth’s Climate Change” http://bcs.whfreeman.com/ruddiman/
If the sea ice melts,
they may go extinct.
Global
Climate Change:
Actual Effects
Increased
Temperatures will
Change Earth’s
Biomes.
• Wildlife is affected.
The Golden Toad
of Costa Rica has
not been seen
since 1989.
It is thought to be
extinct.
We are causing a Biodiversity Crisis!
• Globally, at least 112
amphibian species have
disappeared since 1980.
• Medicinal plants are going
extinct before their uses can
be discovered.
• Biomes are reduced in size
until they can no longer
support their communities.
Madagascar’s rosy periwinkle, a newly
discovered source of anticancer drug.
We are causing a Biodiversity Crisis!
Anthropogenic (human caused) sources of
the crisis:
1. Habitat Destruction
–
We have altered and used ~50%
of land and water.
2. Introduced species
–
Non-native species eliminate
native species.
3. Overexploitation
–
Reduced numbers due to
commercial harvest and sport
hunting.
Anthropogenic Impact on the
World’s Oceans
Anthropogenic Impact on the
World’s Oceans
• The sea represents the last major scientific frontier on planet earth.
• New species are discovered with every ocean expedition.
• A new study published today in Science Magazine states “Over 40%
of the world's oceans are heavily affected by human activities and
few if any areas remain untouched.”
• The most impacted sites:
– The North Sea, the South and East China Seas, and the Bering Sea
– The coastal area of Europe, North America, the Caribbean, China and
Southeast Asia
• The least impacted sites:
– Near the poles
– Along the north coast of Australia
– Small, scattered locations along the coasts of South America, Africa,
Indonesia and in the tropical Pacific
The National Center for Ecological Analysis and Synthesis, http://www.nceas.ucsb.edu/GlobalMarine
Anthropogenic Impact on the
World’s Oceans
Pollution from Commercial Shipping
The National Center for Ecological Analysis and Synthesis, http://www.nceas.ucsb.edu/GlobalMarine
The National Center for Ecological Analysis and Synthesis, http://www.nceas.ucsb.edu/GlobalMarine
Homework
1. Read the article, "Sea Otters as a Keystone
Species" posted under "Articles" on the
website. Describe how the Sea Otter plays a
pivotal role in species diversity in the two
ecosystems described.
2. Highest-level consumers need to eat a lot
more food (regardless of their size) to get the
same energy as primary consumers get from
much less food. Why is this?
3. Give one example of the effects of climate
change that you have read about or
witnessed.