Why are there so many different biomes

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Summary
Why are there so many different biomes ?
Because of different global climate conditions,
which are mainly driven by average temperature
and rainfall.
Example of Biomes Desert, Tropical Rainforest,
Temperate Forest
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Chapter 7 Aquatic Ecology
The two major aquatic life zones, Saltwater or
Freshwater are determined by the water salinity.
Salinity the amount of salt mainly sodium
chloride ( NaCl table salt) dissolved in
water.
Saltwater or Freshwater are similar tropic
structured -Phytoplankton primary producer,
photosynthesis. -Zooplankton primary and
secondary consumers. -Necton larger bodied
consumers i.e. fish, whales. -Decomposer break
down of organic material.
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Coastal Zone / Wetlands

• Importance
• nutrient rich
• high primary productivity
• nurseries for fish other aquatic animals
• breeding areas for waterfowl shorebirds
• filter water pollutants

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Coral Reefs

• What Are Coral Reefs?
• located in coastal zones of tropical oceans
• formed by mutualism between polyps algae
• polyps secrete hard limestone deposits that
  remain when polyps die
• Limestone calcium carbonate CaCO3

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Coral Reefs

• Importance
• high biodiversity, like tropical rain forests of
  ocean
• Removing of CO2 from the atmosphere
• protect coastlines from storms high waves
• nurseries for many fish species
• disappearing

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Coral Reefs

• Coral Bleaching
• The algae within the corals die off.
• WHY?
• Runoff of silt increases water turbidity and
  thereby
• prevents photosynthesis.
• Increase in water temperature and UV radiation
  leads to physiological stress.
• Consequences
• Unable to grow, and repair leads to dieing of
  coral reefs.
• Currently over 60 of the worlds coral reefs
  are
• threatening by human activities.

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Freshwater Ecosystems Lakes
Classification of lakes by the nutrient input
which also determines the primary
producers. 1. Oligotrophic lakes (poor) small
supply of nutrients. 2. Eutrophic lakes
(well-nourished) excessive supply of nutrients
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Oligotrophic Lake

• low supply of nutrients
• low primaryproductivity
• clear water
• few phytoplankton fish

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Eutrophic Lake

• excess supply of nutrients
• high primaryproductivity
• murky water
• large phytoplankton populations

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Human Impacts

• Eutrophication (fertilizer)
• Pollution (waste, sewer)
• Sediments (erosion)
• Canalization
• Introduction of exotic species (Fish, plants)
• Change of flow
• more floods (Summer 02 in Europe)

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Chapter 8 Community Ecology
What determines species diversity in communities?

• In terrestrial communities
• Latitude (distance from Equator)
• In Aquatic communities
• Water Depth

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Terrestrial Communities Latitudinal Species
Diversity
Species diversity of most terrestrial plant and
animal species increases toward the equator.
Tropical rainforests have the highest species
diversity, while the polar areas have the
lowest. But why do we find this latitudinal
species diversity pattern?
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Why do we find this latitudinal species
diversity pattern?
Actually we still have no clue, but several
hypotheses exist
1. Resource availability Climate conditions
Higher amounts of sunlight and rainfall leads to
more reliable resources for primary producers
and consumers in the tropics.
2. Disease pressure Because there is no winter
which could reduce parasite densities no single
species can dominate the community. Compare an
oak forest with a tropical forest.
3. Speciation rate Higher mutation and
speciation rates in warmer climates, which can
lead to higher number of new species.
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Why do we find this latitudinal species
diversity pattern?
4. Coevolution Higher species diversity leads
to more interaction among species, which
promotes coevolution and specializations among
species.
For Example Pollination, Seed dispersal, Ant-Plan
ts,
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Types of Species
Different species play different roles within an
ecosystem. Some species play a more important
role for the maintenance and structure of an
ecosystem tha others.
1. Keystone species 2. Indicator species
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Keystone Species

• Species that play a critical role in an
  ecosystem.
• Strong interaction with other species affect the
  health and survival of other species.
• Those interaction include
• pollination (coevolved species, bats,
  hummingbirds)
• dispersal of seeds (coevolved species, Brazil
  nuts )
• habitat modification (beaver, elephant)
• top-down predation (alligator, sea otter)

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Keystone Species

• They can be identified ones they are removed i.e.
  locally extinction. The lost of Keystone species
  leads to an ecological meltdown.
• e.g., sea otters are keystone species because
  they
• prevent sea urchins from depleting kelp beds
• e.g., flying foxes are keystone species because
  they pollinate disperse tropical trees such
  as durian
• e.g., alligators in the Everglades make
  waterholes, which are refuge for many fish and
  bird predators during the dry season.

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Indicator Species

• Species that serve as early warnings (for humans)
  that a community or ecosystem is being damaged
• e.g., northern spotted owls indicator of healthy
  oldgrowth forest.
• e.g., bald eagle, and DDT contamination
• e.g., amphibians, respond to a wide range of
  anthropogenic changes i.e. temperature,
  UV-radiation, pollution, habitat destruction and
  fragmentation.

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Species Interactions
Effects of one species on another may be
negative, positive, or neutral. These
interactions regulate population density and
species diversity.
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Species Interactions

• Five kinds of interactions
• interspecific competition ( / )
• predation ( / )
• parasitism ( / )
• mutualism ( / )
• commenalism ( / 0)
• Symbols negative, positive, 0
  neutral interaction

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Interspecific Competition

• when two or more species use the same limited
  resource (food, space, etc.) and adversely affect
  each other
• /
• e.g., fire ants native ants in North America
• e.g., plants competing for light, water etc.

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Resource partitioning decreases interspecific
competition

• Resource partitioning reduces competition and
  allows sharing of limited resources (i.e. food).
  Thereby it allows the coexistence of more
  species.
• Resource partitioning
• at different times,
• in different ways, or
• in different places.

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Predation

• members of one species (predator) feed on another
  species (prey)
• /
• e.g., lion feeding on zebra

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Parasitism

• one organism (parasite) lives on part of another
  organism (host)
• /
• e.g., flea, ticks living on a dog
• e.g., malaria
• e.g., fungus (athletes foot)

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Mutualism

• two species interact in a way that benefits both
• /
• e.g. pollination, seed dispersal
• e.g., coral reef (algae polyp)
• e.g., lichens (algae fungi)
• e.g., clownfish anemones

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Commensalism

• one organism benefits from another, but neither
  helps nor harm that other organism
• / 0
• e.g., epiphyte growing on a tree

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Ecological Succession

• Primary and Secondary Succession
• gradual fairly predictable change in species
  composition with time
• some species colonize become more abundant
• other species decline or even disappear.

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Ecological Succession
Why does succession occur? When a system goes
through succession, the gradual changing
environment favor new / different species /
communities. For example, when a treefall gap
becomes colonized by sun loving pioneer plants
they eventually create less suitable conditions.
Ultimately, they will be replaced by different
species which require less sunlight.
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Primary Succession

• gradual establishment of biotic communities in an
  area where no life existed before.
• No preexisting seed bank.
• e.g., succession on newly formed islands (i.e.
  volcanic origin) succession after the retreat
  of a glacier.

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Primary Succession
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Secondary Succession

• gradual reestablishment of biotic communities in
  an area where a biotic community was previously
  present.
• There is a preexisting seed bank.
• treefall gaps (remember?!)
• e.g., "old field succession"
• e.g., forest fire

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Secondary Succession
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Animal Succession
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Disturbance

• discrete event that disrupts an ecosystem or
  community
• examples of natural disturbance treefalls,
  fires, hurricanes, tornadoes, droughts, floods
• examples of humancaused disturbance
  deforestation, erosion, overgrazing, plowing,
  pollution,mining, you name it
• Disturbance can initiates primary and/or
  secondary succession.

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Chapter 9Conservation Biology

• What is Conservation Biology?
• interdisciplinary science that deals with
  problems of maintaining Earth's biodiversity.
• Originated in the 1970s Conservation Biology is
  the youngest biological branch of science.
• It has two main goals
• Investigate human impacts on biodiversity
• Develop strategies to maintain biodiversity

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Conservation Biology

• three underlying principles
• biodiversity ecological integrity should not be
  reduced by human activity
• humans should not cause extinction
• best way to preserve biodiversity ecological
  integrity is to protect intact ecosystems
  sufficient habitat.

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Some Human Impacts on Ecosystems

• fragment degrade habitat
• eliminate some predators (wolves, sharks)
• introduce exotic species (deliberate
  accidental)
• overharvest potentially renewable resources
  (fishing, timber)
• Pollution, fertilizer run off, (eutrophication,
  coral bleaching)

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Habitat Fragmentation

• the process by which human activity breaks
  natural ecosystems into smaller smaller pieces
  of land
• concern about whether habitat size, shape
  quality sufficient to maintain viable populations
  of wild species
• large predators (e.g., grizzly bears),
  migratory species (e.g., bison), require large
  expanses of continuous habitat

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Corridors

• long areas of land that connect habitat that
  otherwise would be fragmented (isolated)
• permit movement of migratory animals ensure
  (genetic diversity) interbreeding of plant
  animal populations

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Ecosystem Restoration

• Can we restore damaged ecosystems?
• yes, but prevention easier cheaper
• natural restoration slow
• active restoration requires considerable effort
  expense
• restoration requires understanding of ecology
• not possible to undo all ecological harm, e.g.,
  extinct species can not recover.

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Review session is September, 27 First exam
(chapter 1-9) is October, 2