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Ecology –
Chapters 15 - 18
Populations
• Population – all the individuals of a
species that live in one area at one time.
• Examples – all the red squirrels in Red
Wing, all the oak trees in a forest, all the
leeches in a lake
3 Key Factors of a Population
• Size – Number of individuals
(ex. 5,167,101 people live in MN)
• Density – Number of individuals in a given
area (ex. Twin Cities area is densely
populated)
• Dispersion – Way individuals are arraigned
Population Growth Rate
• Exponential Growth – curve resulting from
steady population growth
• Carrying capacity – maximum number or
individuals an environment can support
What determines the carrying
capacity?
• Predators
• Disease
• Availability of Resources
– Food
– Water
– Space
Fluctuations in population size
Populations change due to
relationships between species
Coevolution
• Coevolution – long term, interdependent
changes take place in two species as a
result of their interaction.
Ecology
• Ecology is the study of interactions
between living organisms with one another
and their physical (nonliving) environment.
• Habitat – place where a species lives.
• Ecosystem – All the living things that live
in an area and its physical environment.
Abiotic Factors
• Non-living components of an ecosystem.
• Examples
– Sunlight, air, soil, nutrients, water, temperature
Biotic Factors
• Living components of ecosystem
• Bacteria, Protists, Fungi, Plants, Animals
Succession
• Ecosystems change over time. Two types
of succession.
– Primary - occurs where life has never
occurred before. (ex. Volcanic rock, glacier
clearings)
– Secondary – occurs where there has been
previous growth. (ex. Abandoned farms,
forest clearings)
Primary Succession
Secondary Succession
Aquatic Succession
Energy Flow through Ecosystems
• Producers – Capture and convert sun’s
energy into chemical energy
• Consumers – Eat / consume plants and
other organisms to obtain energy
• Decomposers – breakdown / recycle
nutrients back into environment
• Trophic levels – show organism’s source
of energy. Energy moves from one level
to another
Producers
Consumers
Decomposers
Trophic Levels
Classes of Consumers
• Herbivore – Eats plants (Primary
Consumer) ex – cow, deer, some ducks
• Carnivores - Eats other consumers ex –
lion, killer whale, snakes, wolves
• Omnivore – Eats both plants and animals
ex. Bears, humans, raccoons
• Detritivores – Obtain energy from organic
wastes or dead organisms. Ex. Worms,
bacteria
Forest Food Web
Aquatic Food Web
Biogeochemcial Cycles
• Biogeochemical cycles – pathways which
form when a substance enters a living
thing then exits back to the physical
environment.
• Examples include:
– Water Cycle
– Carbon Cycle
– Oxygen
– Nitrogen
Water Cycle
Carbon Cycle
Oxygen Cycle
Nitrogen Cycle
Interactions Among Organisms
Parasitism – one organism feeds on or lives
on another organism (host).
Interactions among Organisms
• Predation – one organism feeds off
another
Interactions among Organisms
• Mutualism – both species benefit from
interaction.
Interactions among Organisms
• Commensalism – relationship where one
species benefits and the other is
unaffected
Niche
• Niche – the role an organism plays in an
ecosystem. Examples – diet, reproduction
time, and time of activity.
2 organisms both live in the
same area, but do not compete
due to different requirements
Biomes
• Biome is a biological community which
occurs over a large area of land.
• Biomes are influenced by the climate of
the area. Difference between climate and
weather?
• 2 Climate factors which have greatest
influence on the biome are Temperature
and Precipitation.
Biomes of the World
• Named for the dominate vegetation of the area
TUNDRA
TUNDRA
TIAGA (Coniferous Forest)
TIAGA
Deciduous Forest
Deciduous Forest
Tropical Rainforest
Tropical Rainforest
GRASSLAND
GRASSLAND
DESERT
DESERT
Aquatic Ecosystems
• Freshwater – Lakes, ponds, streams, and
rivers.
• Marine – Oceans and Seas (almost 75%
of the Earth’s surface)
• Wetlands – Swamps, marshes, & bogs
• Estuaries – transition zone between
freshwater river and ocean. Very
productive due to high nutrients coming
from freshwater river.
Aquatic Ecosystem
Estuary
Changing Environment
• Acid Rain – Coal plants emit smoke high
in sulfur. Sulfuric acid results and this
acidic solution falls back to the surface.
Causes lakes, forests, & buildings to be
damaged, especially areas downwind from
the industrialized area.
Changing Environment
• Ozone Layer – Ozone or O3 shields our
planet from the sun’s UV rays. CFC’s
(chemicals used as coolants and
propellants) destroy Ozone molecules.
Exposure to UV radiation results in skin
cancer, cataracts, and eye cancer. Many
countries limit or ban CFCs. Problem is
that CFCs remain active destroying Ozone
molecules for many years.
Changing Environment
• Climate change – Since the 1950s the average
global temperature has steadily increased.
• Greenhouse effect – Our planet is surrounded
by an insulating layer of gas which makes life
possible on Earth. Much like the glass in a
greenhouse, the gases let the sun’s radiant
energy in and traps the heat inside.
• Greenhouses gases - water vapor, methane,
carbon dioxide, and nitrous oxide.
Changing Environment
• As the average temperature has increased
so has the level of carbon dioxide.
CO2 levels fluctuate by season due to winter vs summer
photosynthesis levels in the Northern hemisphere
.
Annual Mean Temperature Anomalies 1901-2005
Annual Precipitation Trends 1901-2005
Changing Environment
• Effects of climate change: source EPA
– Loss of habitat for living things
– Loss of biodiversity
– Sea level rise (.6 to 2 feet in next century)
– Change in temperature and precipitation
patterns will affect world food supply
– Change in forests
– Change in availability of usable water
Changing Environment
• What can be done to combat climate
change.
– Use less energy (efficient light bulbs, insulate
your home, fuel efficient cars)
– Reduce, Reuse, Recycle
– Don’t waste water
– Renewable energy
Environmental Issues
• Loss of Resources – we are using topsoil,
ground water, and some species of living
things at a rate faster than it can be
replaced.
• Human Population Growth – rapid growth
places stress on already limited resources.
• Pollution / Run-off
– Biomagnification
– Algal Blooms
Biomagnification
Solving Environmental Problems
•
•
•
•
•
Conserve Energy
Reduce, Reuse, Recycle
Do not waste our planet's resources
Compost
Educate yourself and others about issues
that affect your area and the world
• Contact lawmakers about their
environmental policy