Ecology
Ecology – is the scientific study of interactions among
organisms and between organisms and their
environment Biosphere – contains the combined portions
of the planet in which all of life exists; land,
water, atmosphere
- Range: 8 km above earth  11 km below
Biome – a group of
ecosystems that have
the same climate and
dominant communities
Ecosystem – a collection
of all the organisms
that live in a particular
place together with
their nonliving,
physical environment
Ten Major Biomes
Biome
Precipitation Temperature
Soil
Diversity
Trees
Grasses
Tropical Rain
Forest
Tropical Dry
Forest
Tropical
Savanna
Desert
high
hot
poor
high
dense
sparse
variable
mild
rich
moderate
medium
medium
variable
mild
clay
moderate
sparse
dense
low
variable
poor
moderate
sparse
sparse
Temperate
Grassland
Temperate
woodland and
Shrubland
Temperate
Forest
moderate
summer hot
rich
moderate
absent
dense
poor
low
medium
medium
rich
high
dense
sparse
rocky,
acidic
low
dense
sparse
Northwestern
Coniferous
Forest
Boreal Forest
Tundra
summer low, summer hot
winter
moderate
moderate
summer
moderate,
winter cold
high
summer mild,
winter cold
moderate
summer mild, poor,
winter cool
acidic
moderate
dense
sparse
low
summer mild, poor
winter cold
low
absent
medium
Communities- different populations that live together in
a defined area
Populations – groups of individuals that belong to the
same species and live in the same area
Species - a group of
organisms so similar to
one another that they
breed and produce
fertile offspring
Ecological Methods
Observation
Experiment
Model Building
Sites
Field site
Experimental plots,
field sites, laboratory
Many sites for data
collecting
Measuring Tools
Tapes, compass,
Global Positioning
System, thermometer,
sensors
Tapes, compass,
Global Positioning
System, thermometer,
sensors
Aerial views, Global
Positioning System,
weather balloons
Magnifying Tools
Binoculars, microscope,
telescope
Binoculars, microscope,
telescope
Satellite images
Written Record
Notes, automated data
storage
Notes, automated data
storage
Automated data storage
Chemical Testing
Test kits
Test kits
Large database,
multiple sensors
Computer/
Calculators
Mathematical analysis
and graphics, statistics
Mathematical analysis
and graphics, statistics
Mathematical analysis
and graphics, statistics,
simulations
Sunlight is the primary source of energy for life on
earth
– Minor energy source: inorganic chemical compounds
Autotrophs or Producer: an organism that can
capture energy from sunlight or chemicals and
produce its own food
Photosynthesis: autotrophs use light energy to power
this reaction to produce their own food
CO2 + H2O (Light)  carbohydrates (food) + O2
– process is responsible for renewing in O2 atmosphere
Chemosynthesis: autotrophs use chemical energy to
produce food
– bacteria in volcanic vents or salt marshes
Heterotrophs or Consumers: organisms that rely
on other organisms for their food
• Herbivores: energy from only plants
• Carnivores: energy from only animals
• Omnivores: energy from plants & animals
• Detritivores: energy from animals remains or
dead matter (worms)
• Decomposers: energy from breaking down
organic matter (bacteria, fungi)
Food Chain: series of
steps in which
organisms transfer
energy by eating or
being eaten
Trophic Level: a step
in a food chain or
food web
How many trophic levels are shown?
What direction does the arrow point?
Food Web: network of
complex interactions
formed by the
feeding relationships
among the various
organisms in an
ecosystem
Trophic Level: a step in
a food chain or food
web
Only part of energy stored in one trophic level is
passed to the next
– Much of energy is used for life processes; metabolism
– Much energy is converted to heat
~ 10% of energy passed from one trophic level to
the next
Energy Pyramid
Shows the relative
amount of energy
available at each trophic
level. Organisms use
about 10 percent of this
energy for life processes.
The rest is lost as heat.
Biomass: total amount of living tissue in a trophic
level
Biomass Pyramid
Represents the
amount of
living organic matter
at each trophic level.
Typically, the greatest
biomass is at the
base of the pyramid.
Pyramid of Numbers
Shows the relative
number of individual
organisms at each
trophic level.
• What are the most abundant elements in
living organisms?
• Matter is recycled between ecosystems
Biogeochemical cycles: process in which
elements, chemical compounds, and other
forms of matter are passed from one organism
to another and from one part of the biosphere
to another
• Matter is not used up; it is transformed
• Energy travels in a one way path in ecosystems
Water cycle – driven by energy of the sun
Evaporation: liquid  gas (by energy of sun)
Condensation ~ cloud
formation
Precipitation ~ rain,
sleet, snow
Runoff
Seepage
Ground Water
Root Uptake
Transpiration
Transpiration: gaseous water released from leaves of
plants (a product of photosynthesis)
Carbon cycle
• Carbon is found in the air, ocean, rocks, and
essentially element in all living organisms
Carbon cycle
• What is the problem occurring with the
carbon cycle on earth?
Greenhouse Effect
The Greenhouse Effect:
natural situation in which
heat is retained in the
atmosphere
Green Houses Gases:
Sunlight
Some heat
escapes
into space
-CO2
-Methane (CH4)
-water vapor
trap heat energy and
maintain Earth’s
temperature range
Greenhouse
gases trap
some heat
Atmosphere
Earth’s surface
Global Warming: elevated
greenhouse gases causing
increase in average global
temperature
Some heat
escapes
into space
Sunlight
Greenhouse
gases trap
some heat
Atmosphere
Earth’s surface
N2 in Atmosphere
Nitrogen cycle
All organisms require nitrogen
to make amino acids (building
blocks of proteins)
N2 gas 78% atmosphere
NH3
NO3and NO2-
Nitrogen fixation: bacteria take N2 gas  nitrogen
compounds
- producers use compounds to make proteins
- consumers eat producers and make their own proteins
- decomposers return nitrogen to soil as ammonia (NH3)
when organisms die
Denitrification: Soil bacteria convert nitrates (nitrogen
compounds)  N2 gas
Nitrogen fixing bacteria often live in nodules on legume roots
Legumes - alfalfa, clover, peas, beans, lentils, soy, and peanuts
Phosphorus Cycle
• All organisms require
phosphorus to form part
of DNA (essential
molecule that contains
the genetic code for all
life processes)
• P does not enter
atmosphere
• most P is stored in land,
rock, soil, minerals
• plants bind phosphate
for organic use through
food web
Primary Productivity: rate organic matter is
produced by producers by photosynthesis and
chemosynthesis
Do you think the primary productivity on earth is greater in summer or
winter?
Limiting Nutrient: nutrient least in quantity that
will slow production by producers (often P)
Algal Blooms caused
by influx of limiting
nutrient
Problems
Increases aerobic bacteria
Lowers oxygen levels
Other organisms like fish
can die
Blocks light to lower plants
Algae builds up as
sediment and decreases
depth of water
Organisms not only live together in ecological
communities, but they also constantly interact
with one another. These interactions, which
include predation and competition, help shape
the ecosystem in which they live.
1. Based on your own experiences, define
predation. Give one example of predation.
2. Based on your own experiences, define
competition. Give one example of
competition.
Biotic Factors: biological influences on an
organism in an ecosystem
Abiotic Factors: physical or nonliving factors
that shape an ecosystem
Abiotic Factors
Biotic Factors
ECOSYSTEM
Habitat: area where an organism lives (biotic & abiotic factors)
Resource: any necessity for life (water, nutrients, light, food,
space)
Ecosystems are always changing due to natural & human
disturbances
• Niche: full range of physical & biological conditions in
which an organism lives and the way in which the organism
uses those conditions
(temperature range needed to live; what eats it; what it
eats....)
• Competitive Exclusion Principle: no 2 species can have
same niche
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Bay-Breasted Warbler
Feeds in the middle
part of the tree
Spruce tree
Yellow-Rumped Warbler
Feeds in the lower part of the tree and
at the bases of the middle branches
• http://www.youtube.com/watch?v=z31yZtegZ8
Community Interactions
1. Competition: organisms of the same or different species attempt to
use an ecological resource at the same place at the same time
2. Predation: an interaction in
which one organism captures
and feeds on another
organism
3. Symbiosis: any relationship
in which two species live
closely together
Community Interactions
1. Competition
2. Predation
3. Symbiosis: any relationship in which two
species live closely together
A) MUTUALISM
B) COMMENSALISM
C) PARASITISM
Community Interactions
1. Competition
2. Predation
3. Symbiosis: any relationship in which two species live
closely together
A) MUTUALISM
B) COMMENSALISM
C) PARASITISM
ACTIVITY:
In groups title, draw and describe and example
each type of symbiosis.
3. Symbiosis
A) MUTUALISM: type of symbiosis in which
two species benefit from the relationship
3. Symbiosis
B) COMMENSALISM: type of symbiosis in
which one species is helped; other is
neither helped nor harmed
3. Symbiosis
C) PARASITISM: type of symbiosis in which one
organism lives on or inside another organism and
harms it
Characteristics of Populations
• Geographic distribution
• Density
• Growth rate
Population density: number of individuals per unit area
Three factors that affect population size:
1. the number of births
2. the number of deaths
3. the number of individuals that enter or leave the
population
• A population grows if its birthrate is greater than its
death rate
• Immigration: the movement of individuals into an area
• Emigration: the movement of individuals out of a
population
Why move? Move to find new territory; Shortage of food
Exponential growth occurs under ideal conditions: a
population has abundant space and food and is protected
from predators and disease
- Plots to create a “J-Curve”
Exponential Growth: growth pattern in which the individuals
in a population reproduce at a constant rate
Logistic Growth
• a few individuals in a new environment at first unlimited food –
results in exponential growth
• as resources become less available the growth of a population stops
or slows
• plots to create “S-Curve”
Logistic Growth: occurs when a population’s growth slows or stops
following a period of exponential growth
• 1. Occurs when birth rate decreases
3. immigration decreases
• 2.death rate increases
4. emigration increases
Carrying Capacity: largest number of individuals of a population that an
environment can support
Time (hours)
http://www.briarcliff.edu/departments/biol/BIO111/anima/logistic_growth_vid.m
ov
Based on the information in
the table, what part of the
graph represents the world
population? Explain.
Industrial
Revolution
begins
Agriculture
begins
Plowing
and
irrigation
Bubonic
plague
Imagine a small island that has a population of five
rabbits.
1. How might each of the following factors affect
the rabbit population?
a. climate
b. food supply
c. Predation
2. Now imagine another small island that has a
population of 500 rabbits. How would the same
factors affect this population?
3. Which of the factors depend on population
size? Which factors do not depend on population
size?
Limiting Factor: A factor that causes population growth to
decrease
• Density-Dependent Limiting Factor: a limiting factor
that depends on population size
– Operate most strongly when a population is large and dense
1) Competition
– Intraspecies competition: between organisms of the same
species
– Interspecies competition: existing between different species
• major force behind evolutionary change
• evolve to occupy separate niches
2) Predation
• Predator-Prey Relationship: mechanism of population
control in which a population is regulated by predation
3) Parasitism and Disease
– microscopic bacteria, tapeworm etc
Limiting Factor: A factor that causes population growth to
decrease
• Density-Independent Limiting Factor: affect all
populations in similar ways, regardless of the
population size
• Often results in a crash in population size
• natural disasters
• unusual weather
• seasonal cycles
• human disturbances
Environments are always changing
• Most populations can adapt to a certain amount of
change
• Though major upsets in an ecosystem can lead to longterm declines in certain populations
Biodiversity: the sum total of the genetically based
variety of all organisms in the biosphere
Ecosystem Diversity: the variety of habitats, communities,
and ecological processes in the world
Species Diversity: the number
of species in the biosphere
(1.9 million discovered; many
millions undiscovered)
Genetic Diversity: the sum
total of all the different forms
of genetic information carried
by all organisms living on
earth today
Biodiversity is one of Earth’s
greatest natural resources
1. Foods
2. Industrial
products
3. Medicines –
*anticancer/
antidepressant
drugs etc.
Threats to Biodiversity
• Human activity can
alter ecosystems and
decrease biodiversity;
extinction of species
- Pollution - Hunting
- Habitat fragmentation
Invasive Species: any organism that
has been relocated (accidentally
or intentionally) to a non-native
location
– Invasive species can adversely affect
the new habitat
– Out compete native organisms;
decrease biodiversity/ lead to
extinctions
• Africanized Honey Bees
• Write one paragraph summarizing
the information shown in the film.
• Do you see this situation as an
ecological problem? Explain.
• What do you think should be done
to prevent further migration of the
Africanized Honey Bee?
http://www.youtube.com/watch?v=d-7kKqgPEGs&feature=player_embedded
Evolution results in increases and decreases in
biodiversity by:
• mutations
• natural selection
– can lead speciation (new species) and extinctions
The environmental factors that can affect
biodiversity:
• 1) natural causes
• 2) changes in climate
• 3) human activity
• 4) introduction of invasive, non-native species
60
2400
50
2000
40
1600
30
1200
20
800
10
400
0
1955
0
1960
1965
1970
1975
Moose
1980
1985
1990
1995
Wolves
1.What organisms are shown on the graph?
2.Explain what happened to the populations of
each organism from ~1958 to 1997.
3.Do you think the two different populations had
an effect on the others population size? Explain.