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Ecology
Study of interactions among organisms…. &
between organisms with their environmental
factors3-The Biosphere
Biosphere
• The portion of the Earth that supports life
• Composed of two parts:
1. Biotic factors – the living organisms that inhabit an
environment
• All organisms depend on others directly or
indirectly for food, shelter, reproduction, or
protection
2. Abiotic factors – the nonliving parts of an organisms
environment
• Air currents, temperature, light, moisture
• Have effect on living things and often determine
which species can survive in an area
Levels of organization in an organism
• Chemicals make up
cells…
• Which make tissues…
• Organs…
• Systems…
• And finally, the
individual organism
Levels of organization in ecology
• In Ecology, we begin with the individual
and move through the levels to the planet,
Earth
Species
• Group of organisms with similar characteristics
• Able to breed and produce fertile VIABLE offspring
Species
Hybrid
Populations
• Group of individuals (of
the same species) that
live in the same area
• Example?
• All the fire ants in
a pasture
Community
• Groups of different
populations that live
together
• Examples?
• All the ants, birds,
grass, cows, etc
a pasture
in
Ecosystem
• Collection of all organisms (biotic)
that live in a particular area,
together with their non-living
(abiotic) parts of an environment
• Examples of abiotic factors??
• Climate, soil type, amount of
rainfall, etc
Southern Pine Ecosystem
Fort Bragg, North Carolina
Community Ecology
• Habitat – a specific place where an organism lives out his life
• Niche – the role an organism
plays in the environment
Symbiotic Relationships – two organisms living
in close association with one another
1. Competition (-/-)
• compete for limited resource
• Food, mate, territory
2. Predation (+/-) – Hunt and kill your prey
3. Parasitism (+/-)
4. Mutualism (+/+)
• lichens (algae & fungus)
5. Commensalism (+/0)
• barnacles attached
to whale
Symbiosis – two organisms living in close
association with one another

Mutualism


Commensalism


The act of two organisms utilizing one another. Both
thrive and help each other.
The act of one organism utilizing another living
organism. One thrives and the other is neither harmed
nor helped
Parasitism

The act of one organism feeding upon another living
organism. The parasite thrives to the host’s
detrimentand the host is harmed.
Symbiotic Relationships
commensalism
mutualism
+/+
+/0
+/-
predation
competition
-/-
Types of Consumers:
Herbivores
(a.k.a. primary
consumers)
feed directly on
producers
Types of Consumers:
Carnivores (a.k.a.
secondary consumers)
feed on other animals
Types of Consumers:
Omnivores
• feed on both plants and
animals
• can be either primary or
secondary consumers,
depending on food chain
Scavenger
• An animal or other organism that feeds on
dead organic matter
Types of Consumers:
• Decomposers/Saprophyte/Detritivores
• feed on (and recycle) dead or decaying matter
• completing the chain, by returning nutrients needed
by producers to the environment
Scavengers eat dead
things but do not recycle
Decomposers feed on dead
things AND recycle them
Energy flow through the biosphere
• Autotrophs (producers)
• organisms that make their own food
• Heterotrophs (consumers)
• Rely on other organisms for their food supply
AUTOTROPHS
Water + CO2  Sugar + O2
HETEROTROPHS
Sugar + O2  water + CO2
What’s the ultimate source of energy for all life?
Food chain
• Series of steps in
which organisms
transfer energy by
eating and being
eaten
• Arrow always points
the direction of
energy flow…..to the
consumer
Food Chain
• The pathway of
energy that
DECREASES as it
passes through the
trophic (feeding)
levels
• Trophic level of an organism
is the position it occupies in a
food chain
Food web
• Network of complex
interactions, linking all
of the food chains
together
• Show ALL the possible
feeding relationships
• Many connections
throughout ecosystem
Ecological Pyramids
• Energy
Pyramid
• Biomass
Energy
Lost as
Heat
Pyramid
• Numbers
Pyramid
Hawk-eye Question: Why are all three shaped as a pyramid?
What is the relationship between the numbers of
producers and Consumers?
How does this relate to the energy flow through the
ecosystem?
pyramid of numbers
Energy Pyramid
ONLY 10% of energy is passed on to next level
So fewer and fewer
organisms can be
supported at each level
Biogeochemical cycles:
• Water (hydrologic)
cycle
• Driven by solar
energy
• Recycles water,
which is primary
component of all
life
• Phosphorus Cycle
• driven by decomposing
bacteria & fungi
• phosphorus is an
important component of
ATP, Nucleic acids, &
phospholipids
CO2 in
Atmosphere
Carbon Cycle
• The Carbon Cycle is driven
mainly by TWO processes:
• Photosynthesis the process by
which producers convert sunlight
into a useable form of energy
CO2 in Ocean
• Cellular Respiration overall
process by which the body gets
and uses oxygen and gets rid of
carbon dioxide
Nitrogen Cycle
• driven by decomposition by nitrifying bacteria and fungi
• atmospheric nitrogen must be converted to a usable
form that plants can use NITRATE
N2 in Atmosphere
NH3
NO3 –
and NO2 –
What form of nitrogen can plants
use?
• Atmospheric Nitrogen… N2?
• Proteins?
• Amino Acids?
• Ammonia… NH3?
• Ammonium… NH4?
• Nitrite… NO2?
•
Nitrate … NO3?
Day 2
Ecological Succession
IV. Ecological Succession
• transition in species composition over time
• SLOW process, can take years or decades
• usually occurs after a disturbance
• Two types: Primary and Secondary
Mt. St. Helens
1. Primary Succession
• Takes place over land where there are NO living
organisms.
• Ex. Bare rock, volcano created new island
Succession of Species
pioneer species
lichens & mosses
compete well in high sunlight
grasses
more shade tolerant species
shade tolerant species
stable community
climax forest
bushes & small trees
trees
2. Secondary Succession
• Existing community cleared, but base soil is still intact
• Ex. Forest fire, harvesting, hurricane
Mt St Helens Vid Clip
burning releases
nutrients formerly
locked up in the
tissues of tree
the disturbance
starts the process
of succession
over again
Bastrop Fire
Bastrop Fire
Vid of Bastrop Sept 2015
IIV. Species diversity
• Greater diversity = greater stability
• Greater biodiversity
offers:
 more food resources
 more habitats
 more resilience in face
of environmental
change
Populations
• members of the same species that reside in the same
area
Characteristics of populations
a. Geographic
distribution:
Where do they live?
b. Density:
How many are found
in a given unit of area
c. Growth rate:
How quickly do they
grow?
Daisy population
Factors affecting population growth?
1. Birth rate:
number of offspring
per time period
2. Death rate:
number of deaths per
time period
3. Migration rate
movement in and out
of populations in a
period of time
• Immigration: in
• Emigration: out
Exponential growth
• Occurs when individuals in a
population reproduce at a
constant rate
• Only under ideal conditions
Exponential growth activity
• White flies have a 21 day life span
• During their life span the female
will lay approx. 120 eggs
• Calculate the exponential growth
of one pair of flies for 6
generations.
• For this experiment we will
assume that no death occurs
Logistic growth
• Occurs when a population’s growth rate slows or stops,
following a period of exponential (geometric) growth
• Carrying capacity:
that a given
can support
largest number
environment
Click image to play video.
Limiting factors
• cause population growth to stop
• Density-dependent factors depend upon population
size:
•
•
•
•
Competition
Predation
Parasitism
Disease
Competition
• Occurs when 2 species occupies the same niche &
habitat
• What are some things they compete for?
Competition
• Using this 1990
census map of US
population
densities, what can
one deduce at
resource
competition
between the
different parts of
the country?
How can competition explain
population size in nonhuman
species?
Predation
• Predator: one that
consumes or exploits a
particular species for self
gain
• Prey: one that is
consumed or exploited
• What would you expect to
happen to prey
populations if the
predator numbers
increased or if predator
numbers decreased?
Figure 5-7 Wolf and Moose Populations
on Isle Royale
60
2400
50
2000
40
1600
30
1200
20
800
10
400
0
1955 1960
0
1965
1970
1975
Moose
1980
1985
1990
1995
Wolves
Describe the relationship between the wolf and
moose populations shown in the graph.
Predator-Prey relationships
Parasitism and Disease
• Both deplete the host
organism of vital
minerals and nutrients
to sustain life.
• Death of the organism
results in the decline of
population size.
Heart worms (roundworms) as
exposed by a veterinarian
Density-independent factors
• Limiting factors on population size,
regardless of the
number of individuals
in the population
•
•
•
•
Weather
Natural disaster
Seasonal cycles
Human activities (habitat destruction)
Corals that have died from weather
changes, leading to increased
water temperature and pollution.
Day 3
Historical Human Population Growth
Industrial
Revolution
begins
Agriculture
begins
Plowing
and
irrigation
Bubonic
plague
It took 500,000 years to reach 1 billion
& less than 200 years to reach 5 billion.
What might be some reasons why?
What’s the carrying capacity for the human
population?
What if it’s right here? ---------------------------
But, what if it’s right here? ---------------------------
(We do know it lowers when pollution occurs)
Age structure diagrams (population profiles):
graphs showing numbers of people
in
different age groups in the
population
U.S. Population
Males
Females
Rwandan Population
Males
Females
What conclusions can be drawn from these graphs?
Human activities that affect the biosphere
• Hunting& Gathering
• Agriculture
• Industry
• Urban development
• Austin Smart Growth Initiative
Types of resources
Nonrenewable resources:
• unable to be replenished
through natural means
• Ex: fossil fuels, natural gas
Renewable resources:
• able to be replenished but is
not unlimited
• Ex: freshwater
Sustainable development
• A way to use natural
resources without
causing long term
environmental problems
• This plan takes into
consideration
environmental,
economic, and
community demands
Problems land resources face
Desertification
• the process of overusing land and
drought leading to the formation
of arid, desert lands that cannot
sustain agriculture
Soil erosion
• loss of topsoil layer from over farming (plowing) lands
Deforestation
• The process of cutting down (logging) forests for lumber and land.
• Leads to severe erosion during heavy rains.
• Which can lead to permanent changes to local soils and microclimates.
Overfishing
• Harvesting fish faster than they can be replaced by
reproduction.
• What happens to aquatic food webs if overfishing
continues to occur?
Aquaculture
• raising water animals for
human use
• Pictured to the right are
tilapia fish farms in
Australia that then
export the fish to
markets.
Air pollution
• Combustion of carbon
fuels released nitrogen
and sulfur that combine
with water to form acid
rain.
• Pollutant:
• any harmful substance
that enters the biosphere
from land, air, or water
Acid rain
Why should we preserve biodiversity?
Biodiversity:
• sum total of genetically
based variety of all
organisms in the
biosphere
• Ecosystem diversity
• Species
diversity
Why should we preserve biodiversity?
• Biodiversity is one of Earth’s greatest natural resources.
• Species of many kinds have provided us with foods, industrial
products, and medicines – including painkillers, antibiotics, heart
drugs, antidepressants and anticancer drugs.
Threats to species biodiversity
• Human activity can reduce biodiversity by altering
habitats, hunting species to extinction, introducing
toxic compounds into food webs, and introducing
foreign species to new environments.
Threats to species biodiversity
• Endangered: species that is
declining in population size
• Extinction: species that
disappears from all or part of
its range
Endangered status:
Ailuropoda melanoleuca
Dodo Bird
• The dodo has been extinct
since the mid-to-late 17th
century.
• Its extinction occurred during
recorded human history and
was directly attributable to
human activity
Habitat fragmentation
• When land is developed through or around
ecosystems, the species residing within are impacted
in what way?
Central Park in New
York City is a perfect
example of habitat
fragmentation.
DDT
• First synthesized in 1874, DDT's insecticidal properties were not
discovered until 1939, and it was used with great success in the
second half of World War II to control malaria and typhus among
civilians and troops.
• After the war, DDT was used as an agricultural insecticide, and soon
its production and use skyrocketed
• DDT was banned in most countries in 1972
Biomagnification / BioAccumulation :
• Increasing the concentration of harmful materials up the food
chain
Introduced species
• Humans transport animal and plant species from one
part of the world to another.
• Many of these species can become invasive. They
reproduce rapidly and lack parasites and predators
that helped control their populations “back home.”
Nutrias are native
to South America
but have become
pests in coastal US
cities.
Water Hyacinth
Hydrilla
Kudzu
Fire Ants
Conserving Biodiversity
• To conserve biodiversity and multi faceted approach is best:
• Protection of species
• Protection of habitat
• Protection of biodiversity
Conserving Biodiversity Challenges
• Balancing :
• Public need and economics
• Public policy
• Conservation
Charting a Course for the Future
• Researchers are gathering data to monitor and
evaluate the effects of human activities on important
systems in the biosphere.
• Issues:
• Ozone depletion
• CO2 emissions
• Global warming
• Alternative fuels
• Alternative food sources
Ozone depletion
• Ozone: layer of
concentrated gas that
protects the Earth from
harmful UV rays
• O3
• 1970s, scientists found a
gap in the ozone layer
near Antarctica.
NASA image
Global warming
• Compounding the ozone
depletion was the
buildup of CFCs
(chlorofluorocarbons)
from aerosols and AC
units with Freon.
• CFCs trap heat, leading
to a rise in the global
temperature.
Ozone
Click on image to play video.
Value of a Healthy Biosphere
• More complex and diverse ecosystems are the more stable they are.
• Complexity + Diversity = Stability
• All ecosystems play a role in the health of the biosphere.