Download Principles of ecology

PRINCIPLES OF
ECOLOGY
Chapter 2
Introduction: What is Ecology?
2

The scientific study of interactions among
organisms and their environments
 Shows
relationships between living and nonliving
parts of the world
 Scientists obtain data through observation and
controlled experiments
Aspects of Ecological Study
3



Biosphere = the portion of Earth that supports life
Interactions between living and non-living things
Abiotic factors = nonliving parts of the environment
 Determine

(deserts, grassland, forest, tropical forest, tundra, freshwater,
saltwater)
 Ex:

which species live in a particular environment
air currents, temperature, moisture/water, light, soil
Biotic factors = living parts of the environment
 All
living organisms affect other organisms (food, shelter,
reproduction & protection)
 Ex: plants, animals, decomposers
Levels of Organization
4
Scientists study interactions among organisms at
different levels:
1. Organism – one species

A
zebra
 What does it need to survive?
2. Population – a group of the same species
A
herd of zebras
 Competition for resources
Levels of Organization, cont.
5
3. Community –interacting populations in an area
 zebras,
giraffes, lions, trees, grass
 changes in one population affect the other populations
4. Ecosystem – interactions between the community
and nonliving surroundings
 African
grassland
 Three major kinds of ecosystems:
Terrestrial = land
 Freshwater = ponds, lakes, streams
 Saltwater (marine) = oceans

5. Biome
6. Biosphere
Organisms in an Ecosystem
6

Habitat = the place where an
organism lives


Several species may share one habitat
Niche = the role and position a
species has in its environment –
how it survives & reproduces
 Unique
strategies for finding food
& shelter
 Example: bird beaks – adapted for
different foods or feeding
strategies
Beak Variations in Finches
7
Biodiversity
8

the number of different species
that live in a certain area
How Organisms Get Energy
9

All organisms need energy to survive
Autotroph
Two types of Organisms
10

Autotrophs – use energy from the sun
(photosynthesis) or chemicals (chemosynthesis) to
produce their own food
 Also
called producers – they produce usable energy
 Examples: plants, some bacteria

Heterotrophs – organisms that must eat to obtain
energy
 Also
called consumers – they must consume food to
get usable energy
 Examples: all animals, some bacteria, decomposers
Kinds of Heterotrophs
11

Herbivores – feed on
autotrophs such as
plants, seeds, or algae
 Insects,
deer, rabbits,
squirrels, bees, elephants

Carnivores – feed on
other heterotrophs
 Lions,
coyotes, sharks
 Scavengers eat carrion
& refuse (leftovers from
carnivores)

Ants, beatles, vultures
Kinds of Heterotrophs
12

Omnivores – feed on
animal and plant
materials
 Humans,
raccoons,
opossums, bears

Decomposers – break
down dead organisms
& recycle nutrients
 Fungi
& bacteria
Matter & Energy Flow in Ecosystems
13
The food you eat contains matter (carbon,
nitrogen, oxygen, hydrogen, etc) and energy
 Energy moves ONE WAY – it cannot be recycled
 Food chains – simple models used to show the
movement of energy through an ecosystem

Food Chains
14
Energy moves from autotrophs to heterotrophs,
eventually to decomposers
 Arrows indicate the direction of energy transfer
 Example: Algae  fish  bird

 The
algae is an autotroph. Energy is transferred to the
fish when it eats the algae, then to the blue heron when
it eats the fish

Most food chains have no more than five links
because the amount of energy decreases at each
level.
Trophic Levels
15

Represent a feeding step in the passage of
energy
 Many

species may occupy one trophic level
Food webs express all the possible feeding
relationships at each level in a community
 More
realistic than a food chain because most
organisms depend on more than one food source
 Food webs represent a network of food chains –
overlapping & interconnected
Sample Food Web:
16
3rd order
heterotrophs
2nd order
heterotrophs
1st order
heterotrophs
Autotrophs
Ecological Pyramids
17



Food chains, food webs, and ecological
pyramids show how energy moves in
only ONE direction through an
ecosystem
10% rule – only about ten percent of
the energy at one trophic level is
passed on to the next (the rest is used
for life processes)
Types of Pyramids:
 Energy
Pyramid
 Pyramid of Numbers
 Biomass Pyramid
Energy Pyramid
18
Nutrients in the Biosphere

Nutrients differ from energy in two ways:
 It
is not lost after being used, it will not produces a
product such as heat for the environment
 Passes from one organism to another in a continues
cycle that has no beginning or end
Water Cycle

Consists of three
process:
 Evaporation
 Condensation
 Precipitation
Nitrogen Cycle



Nitrogen fixation –
convents
atmosphere N2 to
ammonium (NH4)
and nitrate (NO3)
Autotrophs will
absorb and
convert to organic
materials
Heterotrophs will
consume in foods
Carbon Cycle


Autotrophs uses
CO2 gases from
the atmosphere
to use in
photosynthesis
Nonphotosynthetic
organism give off
CO2
COMMUNITIES &
BIOMES
Chapter 3
Living in a Community
24

Limiting Factors
 Environmental
factors that affect an
organism’s ability to survive
 Any biotic or abiotic factor that restricts
the existence, population, reproduction,
or distribution
 Food, predators, competing species,
temperature, rainfall, light, soil

Changes in one population may
affect others in the community
Ranges of Tolerance
25

Tolerance = the ability of an organism to
withstand changes in biotic & abiotic factors
 Organisms
must stay within their tolerance range
 Examples:
people and temperature; plants &
water

May affect population size
Succession: changes over time
26
Succession = the orderly, natural changes and
species replacements that take place in the
communities of an ecosystem
 Occurs in stages
 May take centuries
 Two types:
 Primary
Succession
 Secondary Succession
Primary Succession
27

The colonization of new sites
 Avalanche,

volcano eruption, volcanic island
Pioneer species = first species in an area
 Lichen
grows on rocks, breaking them down and
producing soil

Climax community = a stable, mature community
that undergoes little or no change in species
Secondary Succession
28

The sequence of community changes that takes
place after a community is disrupted
 Natural
disasters (hurricane, fire), human actions
 Occurs in areas that previously contained life

Takes less time than primary succession
Biomes
29

Is a major type of ecosystem with its own
temperature ranges, rainfall amounts, and
types of organisms
Aquatic Biomes
30

Marine (Salt Water)
 Location:
Oceans, Estuaries, Photic Zone (with light), &
Aphotic Zone (without light)
 Types of Organisms: Kelp, Whales, Dolphins, Sharks,
Tuna, Crabs, Shrimp, Lobsters, Salmon, Eels, Plankton

Freshwater
 Location:
Wetlands, Rivers, Streams, Ponds,
Lakes, & Creeks
 Types of Organisms: Algae, Muskrats, Ducks,
Geese, Fish, Pike, Carp, Bass, & Catfish
Land Biomes
31






Tundra
Taiga
Temperate Forest
Grassland
Desert
Tropical Rain Forest
POPULATION
BIOLOGY
Chapter 4
Population Growth


Population Growth = an increase in
the size of a population over time
Populations grow exponentially
 The
rate increases because the total
number of reproducing individuals is
increasing
 As the population grows larger, it
reproduces faster

Patterns of population growth
 Depend
on environmental conditions
 Example: Elephants vs. mosquitoes
Stages of Population Growth
1.
2.
3.
4.
5.
Beginning
growth
4
Rapid
growth
3
Leveling off
Carrying
capacity
Fluctuations
2
1
5
Limits to Population Growth (abiotic)



Populations cannot grow indefinitely
Carrying Capacity = the number of organisms
that an environment can support
Two kinds of limiting factors:
 Density-dependent
factors
 disease,
competion, parasites, food
 Bigger influence if population is large
 Density-independent
 Temperature,
factors
storms, floods, drought, habitat
disruption
 Affect all populations
Limits to Population Growth (biotic)

Predation


Predators usually catch and eat the
young, old, sick, or injured individuals of
a population
Competition
When population numbers are large,
organisms must compete for resources
 when the demand exceeds the supply,
the population decreases


Crowding & Stress
Individuals may become more
aggressive, decreased parental care,
decreased fertility, decreased
resistance to disease
 As a result, the population decreases

Symbiosis


Other interaction
between species
Occurs when two
species live in close
contact with each other
for a long period of
time


Host – is the species
that is being used
Symbiot – is the species
that is acting on the host
Symbiosis

Mutualism



Both individuals benefit from
each other
++
Communalism



One benefits the other is not
affected
+0
Parasitism



One benefits the other is
harmed
+ --
Amensalism


One will stop the growth of
another without being affected
by it
0 --
Human Populations


Demography (demographics) = study of
human populations
Several factors affect human population:
 Birth
rates
 Death rates
 Age structure – helps to predict if a
population is growing rapidly
 Immigration – movement into a population
 Emmigration – movement out of a population
Age structure


Demographers collect
data on age structures
of different countries
Tracking data allows
scientists to make
predictions about
population growth
BIOLOGICAL
DIVERSITY &
CONSERVATION
Chapter 5
Biological Diversity

Biodiversity = the variety of life in an area


The number of species that live in a certain area
Terrestrial biodiversity increases as you move closer to
the equator
Canada = 163 mammal species
 United States = 367
 Mexico = 439



The greatest biodiversity is found in warm areas such
as tropical rain forests and coral reefs
Larger islands have more biodiversity than smaller
islands with the same climate
Importance of biodiversity

Organisms are adapted to live together in
communities


If one species is lost, it affects the populations of other
species
Life depends on life
Animals cannot exist without plants
 Many plants cannot exist without the animals that pollinated
them
 Decomposers recycle nutrients and get rid of dead and
decaying material


Biodiversity brings stability to an ecosystem

A pest or parasite may destroy a farm, but not a forest.
Importance to people

Humans depend on other organisms
 Oxygen
supplied by plants
 Diversity of foods to eat

Biodiversity is useful to humans
 Making
new food crops
 Improving people’s health
Loss of biodiversity

Extinction = the disappearance of a species when the
last of its members dies


Almost 40 species of plants and animals in the United States
have gone extinct since 1980
Threatened = When the population of a species
begins to decline rapidly
 Ex.
African elephants have decreased in number due to
hunting

Endangered = when a species’ numbers become so
low that extinction is possible
 Ex.
California condor, Florida manatees, bald eagle,
Sumatran tiger, Galapagos tortoise, etc.
Threats to Biodiversity

Complex interactions among
species make ecosystems unique
and species well adapted to their
habitats


Changes to habitats put organisms in
danger of extinction
Most common threats to
biodiversity
Habitat loss
 Damage to habitats
 Pollution
 Introduction of exotic species

Habitat Changes


The biggest threat to biodiversity is habitat
loss
Habitat fragmentation = the separation of
wilderness areas from other wilderness
areas
 Ex.
Building a freeway, clear-cutting forest
trees, etc.

Habitat degradation = damage to a
habitat by pollution
 Air
pollution
 Water pollution
Strategies of Conservation Biology

Conservation Biology is a new field that implements
plans and methods to protect biodiversity
Resource conservation
 Conservation biologists study law, politics, sociology,
economics, and ecology

Legal Protection of Species

President Nixon signed the US Endangered Species Act
into law in 1973.
It is illegal to harm any species on the endangered or
threatened species list.
 Federal agencies cannot fund any project that would harm
these animals



Cannot change an ecosystem where endangered or
threatened species live
Other countries have established similar laws

International trade is controlled regarding certain species
Preserving habitats

National Parks & Preserves
 Protecting
whole communities and ecosystems is the best
way to protect the organisms that live there.
 Ex. Yellowstone, Yosemite, etc



Park rangers are hired to manage the parks and
ensure protection of organisms
Sustainable use = allowing people to use the
resources without damaging the ecosystem
Habitat corridors = natural strips that allow the
migration of organisms from one area to another
 Prevents
isolation and habitat fragmentation
Reintroduction programs

The release or organisms into an area where their
species once lived
Organisms are captured and bred, then returned to the wild
 Most successful when organisms are transported to new,
sustainable habitats
 Ex. Brown pelican, gray wolf, panda breeding program, etc


Captivity = an organism that is held by people
Zoos & aquariums
 Animals kept in captivity may lose the necessary behaviors to
survive in the wild
