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The study of the interactions
between organisms and the living
and nonliving components of their
environment.
Table of Contents: Ecology
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Levels of Organization
Organism Ecology (vocabulary)
Ecosystems and Energy
Ecosystem Recycling
Populations
Succession
Invasive Species
Modern Issues
slides 3-7
slides 8-9
slides 10-17
slides 18-20
slides 21-30
slides 31-36
slides 37-41
slides 42-57
Levels of Organization
 Biosphere
– The thin layer of the earth that supports life (as
thin as the skin of an apple!)
Levels of Organization
 Biomes
– Any of the worlds major ecosystems, classified
by predominant vegetation and characterized by
adaptations of organisms to that particular
environment.
– Terrestrial Biomes include
 Tropical forests, Savanna, Desert, Chaparral,
Temperate Grassland, Temperate Broadleaf Forest,
Coniferous Forest, Tundra, High Mountains, Polar Ice
– Aquatic Biomes include
 Lakes, Wetlands, Streams and Rivers, Estuaries,
intertidal zones, oceanic pelagic zones, coral reefs,
marine benthic zones
Levels of Organization
 Ecosystem
– Includes all of the living (biotic) and non living
(abiotic) components within a particular place.
 Biotic Components of a Pond
– includes fish, turtles, plants, algae, insects, bacteria.
– These interact with each other.
 Abiotic Components of a Pond
– water temperature, dissolved oxygen and carbon dioxide,
nitrogen levels, sun light, pH level.
– These are necessary for the living organisms to survive.
Levels of Organization
 Community
– Includes all of the interacting organisms within an area.
 Population
– Includes all of the members of a species that live in one
place at a time.
 Organism
– The individual in a population.
– Represents the simplest level of organization.
– Most studies focus on the individual organism and how
it has adapted to overcome the challenges in its
environment.
Levels of Organization
Organism Ecology
 Biotic Factors - living factors that affect an
organism.
 Abiotic Factors - non living factors that affect an
organism.
 Habitat - where an organism lives
 Environmental Fluctuations
– As the environment changes, an organism must be able
to tolerate those changes otherwise it will stress and
exhibit reduced performance or simply die.
Organism Ecology
 Niche
– Way of life or the role of an organism in its
environment.
 Bacteria recycle nutrients
 Predators keep prey populations under control
 Plants use CO2 and produce O2 also provide food for
grazers.
Ecosystems and Energy
What’s the 10% Rule?
Energy Transfer
 A common characteristic of all living
organisms is they require energy to carry
out metabolic activities.
 Producers
– Usually photosynthetic plants (autotrophs)
– Can also be chemosynthetic (certain bacteria)
Energy Transfer
 Measuring Productivity
– Gross Primary Productivity
 Rate at which producers capture energy
 Energy is used to make sugar which is used for
repairs, for growth or cellular respiration
– Biomass
 Organic matter in the ecosystem
– Net Primary Productivity
 Rate at which biomass accumulates in an ecosystem
– NPP is highest in biomes like tropical rain forests and
estuaries
Energy Transfer
 Consumers are Heterotrophs
– Herbivores - consume producers
 Cows, deer, mice
– Carnivores - eat consumers
 Mountain Lions, bald eagles, snakes
– Omnivores - eat both producers and consumers
 Bears, people
– Detritivores - feed on dead matter
 Vultures, certain beetles
– Decomposers - decay complex molecules of
dead tissue and wastes into simpler molecules
 Bacteria, Fungus
Energy Transfer
 Energy Flow
 Energy in an ecosystem moves from one organism
into another
 Trophic Level
– The organisms position in the sequence of energy transfers
 Food Chain
– A single pathway of feeding relationships in an ecosystem
that shows energy transfer
 Food Web
– a series of interrelated food chains in an ecosystem
Food Chain
Food Web
Ecosystem Recycling
 The Water Cycle
Ecosystem Recycling
 The Carbon Cycle
Ecosystem Recycling
Ecology
Populations:
Growth, Carrying Capacity,
Variables
Population Growth
 If resources, such as food, water and habitats,
were unlimited, then a population of organisms
would grow in an exponential fashion.
 Imagine if this growth
curve represented
mosquitoes, elephants
or people. The earth
would be over-run and
all resources would be
rapidly depleted!
Population Growth
 Fortunately, in nature resources are limited.
 Limited resources slow growth and if you graph
numbers of organisms over time, the graph takes
the shape below.
Population: Carrying Capacity
 Notice the top of the smooth graph is
labeled “carrying capacity”.
 This is the number of organisms that a
habitat can sustain with the available
resources.
 If the number of organisms exceeds the
carrying capacity, the population can begin
to decline.
Population Curve
 Notice the tail on this graph.
 When resources have been overused or depleted,
the organisms begin to die out.
Population: Carrying Capacity
 What happened to
the reindeer on
Matthew Island?
 The reindeer
overused their
resources and
exceeded the
islands carrying
capacity almost
dying out.
Population Size: Variables
 What other factors affect the size of a
population?
– Birth Rates
– Death Rates
– Immigration-the movement of individuals from
other areas.
– Emigration-the movement of individuals out of a
population.
Population Size: Variables
 If the arrows represent actual rates, what would
happen to the size of the population circle if the
death rate arrow was cut in half or the immigration
arrow was doubled?
Population
Population Size: Variables
 If the death rate arrow were cut in half or the
immigration arrow was doubled, the population
circle would increase in size.
Population
Population: Variables
 In the United States, birth rates, death rates and
emigration rate are low but our immigration rate is
climbing. How is that affecting our population size?
Ecology
Succession
Ecological Succession
 Changes in the number and type of organisms in a
community are most apparent after some type of
disturbance to the habitat.
 The disturbed area may be colonized by a variety
of new organisms, which are gradually replaced by
other organisms until a stable group of species
persists within the area.
 This process is called Ecological Succession.
Ecological Succession cont.
 One type of ecological succession is called Primary
Succession.
 In primary succession, a new piece of new real estate,
such as a volcanic island where soil and organisms are
lacking, is invaded by lichens and mosses which are
usually blown in as spores.
 As soil develops, these organisms are overgrown by
grasses, shrubs and trees that are blown in or brought in
by animals.
 Eventually, the area is colonized by plants that become the
main form of vegetation.
 This process can take hundreds to thousands of years.
To the right, the foreground
is bare rock covered with
lichens and mosses. The
middle ground contains a
small amount of soil with
plants. The background is a
stable forest.
Below is an example of
rock covered with lichens.
Ecological Succession
 Secondary succession occurs when an existing
community is cleared by some disturbance such
as fires, glaciation, deforestation, etc.
 Under these circumstances the sequence of
colonization can vary but generally weeds and
other opportunistic plants first invade followed by
grasses or shrubs. These can then be replaced by
trees species.
Secondary succession occurs in areas where plants were
already established but were disturbed. This sequence
represents a once planted field in North Carolina.
Ecology
Invasive Species
(Non-Native)
Invasive Species
 After habitat loss and degradation, mostly due to
human activity, the biggest cause of early
organism extinction is the introduction of harmful
invasive species into an ecosystem.
 Invasive species have been intentionally and
accidentally introduced in the U.S. for years.
 Intentionally introduced species include
– wheat, rice, corn, cattle, poultry.
 Accidentally introduced species include an
estimated 7100 organisms in the U.S. alone
Invasive Species cont.
 Accidentally introduced species include
– Brown tree snakes, Japanese beetles, African
honeybees, zebra mussels, Formosan
Termites, Burmese pythons, Gypsy moths, etc.
 Species like these cost the U.S. public
approximately $261,000 per minute in damage
and control.
Invasive Species
 These invasive species cause so much damage
because they have no natural predators,
competitors, parasites or pathogens when
introduced into a new environment.
 Nonnative species can reduce or wipe-out
populations of many native species, trigger
ecological disruption, cause human health
problems and lead to economic loss.
Invasive Species
Kudzu Vine
Burmese
Python
Formosan
Termite
Gypsy Moth
Catepillar
Ecology
Modern Issues
(Optional Information)
Ecology
 Human Population Explosion
 From 2 Billion in 1930 to 6 Billion in 1996
 Projected to reach over 7.8 Billion in 2050
World Population Projections
Ecology
 Mass Extinctions
– The last extinction occurred 65 mya probably
due to an asteroid impact.
– Currently organisms are going extinct at a rate
unseen since the dinosaurs last died out.
– By 2100, it is expected that one fifth of the
current organisms will be extinct.
– Why? Habitat destruction, over hunting, the
introduction of predators and disease.
Mass Extinction 1
 The following mass extinctions were due to natural
causes.
– First major extinction (c. 440 mya): Climate change
(relatively severe and sudden global cooling)
seems to have been at work at the first of thesethe end-Ordovician mass extinction that caused
such pronounced change in marine life (little or
no life existed on land at that time). 25% of
families lost (a family may consist of a few to
thousands of species).
Mass Extinctions 2-3
 Second major extinction (c. 370 mya): The next such event, near
the end of the Devonian Period, may or may not have been
the result of global climate change. 19% of families lost.
 Third major Extinction (c. 245 mya): Scenarios explaining what
happened at the greatest mass extinction event of them all
(so far, at least!) at the end of the Permian Period have been
complex amalgams of climate change perhaps rooted in plate
tectonics movements. Very recently, however, evidence
suggests that a bolide impact similar to the end-Cretaceous
event may have been the cause. 54% of families lost.
Mass Extinction 4
 Fourth major extinction (c. 210 mya): The event at the
end of the Triassic Period, shortly after dinosaurs
and mammals had first evolved, also remains
difficult to pin down in terms of precise causes.
23% of families lost.
Mass Extinction 5
 Fifth major extinction (c. 65 mya):
– Most famous, perhaps, was the most recent of these events at
the end-Cretaceous. It wiped out the remaining terrestrial
dinosaurs and marine ammonites, as well as many other species
across the phylogenetic spectrum, in all habitats sampled from
the fossil record. Consensus has emerged in the past decade that
this event was caused by one (possibly multiple) collisions
between Earth and an extraterrestrial bolide (probably a comet).
17% of families lost.
Last Extinction Event
The Sixth Mass Extinction
 How is the Sixth Extinction different from previous
events?
– The current mass extinction is anthropogenic (caused by
humans).
 Humans are the direct cause of ecosystem stress and species
destruction in the modern world through such activities as:
– Habitat degradation
– Overexploitation of species
– Pollution
– The introduction of invasive species
Ecology
 Thinning Ozone Layer
– This layer is responsible for protecting life from UV
radiation from the sun.
– CFC’s in the earth’s upper atmosphere cause
ozone (O3) to break down into oxygen (O2).
– This effect is magnified at the earth’s poles.
– A 1992 treaty banned CFC’s (Chloroflourocarbons)
from use, but long-term persistence of CFC’s in the
atmosphere continues to degrade ozone.
– Recent evidence suggests ozone degradation is
slowing.
Total Ozone
Ozone Hole
Ecology
 Modern Issues
– Global Warming
 Carbon Dioxide (CO2) produce by humans has
increase the atmospheric CO2 steadily since the late
1800’s.
Ecology
 Global Warming
– The increase in “greenhouse gases” (CO2, O3,
CH4) is slowly increasing the average
temperature of the earth.
– This is resulting in rising sea level, melting ice
caps, changes in storm patterns and changes in
oceanic current flows.
 Environmental knowledge is essential in
trying to stop and reverse destructive human
practices.