Transcript Ecology & Biomes

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What is
Ecology ?
Population
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Population = Group of same species living
in same area
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Individuals in a population have a high
likelihood of interacting and breeding with one
another
Population Growth

Exponential
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Logistic w/ Carrying
Capacity
Factors the Affect Population
Growth: Density Dept vs Indept
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Density Independent
- Climate
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Density Dept
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the buildup of toxic wastes
Limited food supply
increased disease
predation
Community
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Community: all
populations in a given
area
Community: Niche &
Competition
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A population's niche
= role in the
community
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The sum total of its
use of the biotic and
abiotic resources of its
habitat
Community: Competitive
Exclusion Principle
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Populations of two species cannot coexist
in a community if their niches are nearly
identical
Leads to either:
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Competition & death of one
Natural Selection & resource partitioning
Community: Competition &
Resource Partitioning
Community: Symbiosis
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Symbiosis: interaction between two or
more species that live together in direct
contact
Three types:
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Mutualism
Commensalism
Parasitism
Community: Mutualism
Symbiosis
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Both benefit
Ex.
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Nitrogen-fixing
bacteria and legumes
Community: Commensalism
Symbiosis
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Commensalism = one
benefits , the other is
unaffected
Not as common
Ex
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Algae that grow on the
shells of sea turtles
Barnacles that attach to
whales
Birds that feed on insects
flushed out of the grass by
grazing cattle
Community: Commensalism
Parasitism
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One benefits while
other harmed
Community: Predator / Prey
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Predator: consumer
Prey: food species
Community: Predator / Prey
Coevolution
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Coevolution: as
predators adapt to
prey, sometimes
natural selection
also shapes the
prey's defenses
Community: Prey Defenses
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Mechanical Defenses (quill of porcupine)
Chemical Defenses (poison frog)
Camouflage
Community: Prey Defenses
Mimicry
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Batesian – harmless
mimicking harmful
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Mullerian – both
harmful
Community: Ecological
Succession
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Ecological Succession: transition in the
species composition of a community
following a disturbance
Primary vs Secondary
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Primary succession: gradual colonization of
barren rocks by living organisms, starting with
Pioneer organisms
Community: Ecological
Succession
Primary
Secondary: after
disturbance
Ecosystem: Energy Flow &
Chemical Cycles
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Ecosystem = Community + abiotic factors
in habitat
Two things needed in ecosystem:
ENERGY: flows from the sun, through
plants, animals, and decomposers, and is
lost as heat
CHEMICALS: recycled between air, water,
soil, and organisms
Ecosystem: Energy Flow &
Chemical Cycle
Ecosystem: Energy, Food Chain
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Food chain = flow of
energy and nutrients
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from plants (producers)
to herbivores (primary
consumers)
to carnivores
(secondary and higherlevel consumers)
Ecosystem: Food Chain,
Decomposers
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Detritivores decompose
waste matter – detritus
(break down organic
molecules) and recycle
nutrients (into inorganic)
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Examples: animal
scavengers, fungi,
and prokaryotes
Ecosystem: Energy Food Web
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Ecosystem: Energy Pyramid
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Only ~10%
of energy in
food of each
trophic level
is available to
the next level
- rest used or
lost as heat
Ecosystem: Biomass Pyramid
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Biomass = amount
of living organic
material in an
ecosystem
Based on Primary
production = rate at
which producers
convert sunlight to
chemical energy
Ecosystem: Chemical / Nutrient
Cycles
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Water Cycle
Carbon Cycle
Nitrogen Cycle
Ecosystem: Water Cycle
Ecosystem: Carbon Cycle
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Carbon needed
to make organic
molecules
Carbon fixation
(photosynthesis)
: inorganic
carbon (CO2)
into organic
compound
(sugar)
Ecosystem: Nitrogen Cycle
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Nitrogen plentiful in atmosphere as N2
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But plants cannot use N2
Bacteria in soil (and legume root nodules)
convert N2 to nitrogen compounds that
plants can use
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Ammonium (NH4+) and nitrate (NO3–)
Ecosystem: Nitrogen Cycle
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Nitrogen Fixation (Nitrogen fixing
bacteria): convert N2 gas into Ammonium
NH4
Nitrification (Nitrifying bacteria): convert
NH4 into Nitrates NO3
Denitrification (Denitrifying bacteria):
convert NO3 into N2 gas
Ecosystem: Nitrogen Cycle
Terrestrial Biomes
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Biomes: Tundra
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Treeless artic
tundra,
permafrost (soil)
Cold, wind, lichen
Biomes: Tiaga
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Cold, coniferous
forest
Largest
terrestrial biome
(land-wise)
Long winter,
short wet
summer
Biomes: Temperate Deciduous
Forest
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sufficient
moisture to
support the
growth of
large trees
Biomes: Savanna
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Drier, tropical
areas and some
nontropical
Biomes: Temperate Grasslands
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Temperate
grasslands are
found in the
interiors of the
continents, where
winters are cold
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Drought, fires, and
grazing animals
prevent trees from
growing
Biomes: Desert
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Deserts are the
driest of all
terrestrial biomes
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Characterized by
low and
unpredictable
rainfall
Biomes: Tropical Rain Forest
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Tropical rain forest = most diverse
Biomes: Marine Aquatic
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Oceans cover about 75% of the Earth's
surface
Biomes: Marine Aquatics
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Estuaries = productive areas where rivers meet
the ocean
They provide nursery
areas for oysters,
crabs, and
many fishes
 They are often
bordered by
extensive coastal
wetlands