Download Ecology I

Ecology of Organisms and
Populations
Ch. 18
Learner Outcomes:
 I can define ecology and list the levels
of organization studied in ecology.
 I can differentiate between abiotic and
biotic factors and explain how they can
impact one another in ecosystems.
Ecology
 Study of interactions between
organisms and their environment
 Ecology can be divided into four
increasingly comprehensive levels:
 Organismal
ecology
 Population ecology
 Community ecology
 Ecosystem ecology
Ecology
 Organismal ecology
 Is concerned with
evolutionary
adaptations that
enable individual
organisms to meet
the challenges posed
by their abiotic
environments.
http://www.seabird.org/assets/killer%20whales%20internet%202.jpg
Ecology
 Population ecology
 Is concerned with
populations, groups
of individuals of the
same species living
in the same area.
 Concentrates mainly
on factors that affect
population density
and growth.
http://newsimg.bbc.co.uk/media/images/44609000/jpg/_44609350_puffins512.jpg
Ecology
 Community ecology
 Is concerned with
communities,
assemblages of
populations of
different species.
 Focuses on how
interactions between
species affect
community structure
and organization.
http://www.mass.gov/envir/forest/images/multiLayerForest.jpg
Ecology
 Ecosystem ecology
 Is concerned with ecosystems, which include all the abiotic
factors in addition to the community of species in a certain
area.
 Focuses on energy flow and the cycling of chemicals among
the various abiotic and biotic factors.
http://www.african-books.com/images/Animals/montage.jpg
Components of the
Environment
 The abiotic component
 Consists
of nonliving chemical and
physical factors.
 The biotic component
 Includes
the living factors.
Abiotic Factors of the
Biosphere
 On a global scale, ecologists have recognized
striking regional patterns in the distribution of
terrestrial and aquatic life.
 Global distribution patterns

Reflect regional differences in climate and other abiotic
factors.
Sunlight
 Solar energy powers nearly all ecosystems.
 Availability of sunlight affects aquatic and
terrestrial environments.
http://artfiles.art.com/images/-/Aflo/Sun-Shining-in-BlueSky-Over-Tree-in-Winter-Snow-Biei-Hokkaido-JapanPhotographic-Print-C13062664.jpeg
Water
 Aquatic organisms may face problems
with water balance.
 For terrestrial organisms, the main
water problem is drying out.
Temperature
 Environmental
temperature

http://www.wildherps.com/images/herps/standard/desert_iguana.jpg
http://www.sciam.com/media/inline/A186A7F7-D8EADDDF-0F715313A7DA2A91_1.jpg
Is an important
abiotic factor
because of its effect
on metabolism.
Wind
 Some
organisms depend on nutrients
blown to them by wind.
 Organisms such as plants depend on wind
to disperse pollen and seeds.
 Can also affect the pattern of a plant’s
growth.
http://www.asdk12.org/staff/vanarsdale_mark/pages/Ecology_Images/wind_tree.jpg
Rocks and Soil
 Soil
variation contributes to the patchiness
we see in terrestrial landscapes.
 In streams and rivers, the composition of
the soil can affect water chemistry.
Periodic Disturbances
 Catastrophic disturbances
 Can devastate biological communities.
 After a disturbance,
 An area is recolonized by organisms, or repopulated by
survivors.
 The structure of the community undergoes a succession of
changes during the rebound.
Ecosystems
 What biotic and abiotic factors do you
see in this picture of the rain forest?
Ecosystems
 What biotic and abiotic factors do you
see in this picture of a tundra?
An Overview of Ecosystem
Dynamics
 An

ecosystem
Is a biological community and the abiotic
factors with which the community interacts.
– Energy flow
• Is the passage of energy through the
components of the ecosystem.
– Chemical cycling
• Is the use and reuse of chemical elements within
the ecosystem.
Learner Outcomes
 I can explain how energy flows through
ecosystems from the sun, to producers
to consumers.
 I can identify the different types of
consumers in ecosystems.
Energy
 Flows through an
ecosystem when
consumers feed on
producers.
 Cannot be recycled
within an
ecosystem, but must
flow through
continuously.
Ecosystem Dynamics
 Energy

Depend on the transfer of substances in the
feeding relationships, or trophic structure, of an
ecosystem.
 Trophic

relationships
Determine an ecosystem’s routes of energy
flow and chemical cycling.
 Trophic

flow and chemical cycling
levels
Divide the species of an ecosystem based on
their main sources of nutrition.
Trophic Relationships
 Ecosystems divided into trophic levels
(feeding levels)
 Producers—autotrophs
(mostly
photosynthetic)
 Primary consumers—herbivores
 Secondary consumers—carnivores that eat
herbivores
 Tertiary consumers—carnivores that eat
other carnivores
 Detrivores—consumers that eat dead or
decaying matter
Food Chain/Food Web
Energy Flow in Ecosystems
 Each level in a food
web contains a different
quantity of stored
chemical energy
 When consumers eat
producers or 2
consumers eat 1
consumers, some
energy is lost in each
transfer from one level
to the next
Energy pyramid
 A diagram that represents the cumulative loss
of energy from a food chain.
 10% Rule
• Between each tier of an energy
pyramid, up to 90 percent of the
energy is lost into the
atmosphere as heat.
• Only 10 percent of the energy at
each tier is transferred from one
trophic level to the next.
energy
lost
energy transferred
Biomass Pyramid
 Biomass is a measure of the total dry mass
of organisms in a given area.
tertiary
consumers
75 g/m2
150g/m2
secondary
consumers
primary
consumers
producers
producers
675g/m2
2000g/m2
 Pyramid of Numbers
tertiary
consumers
5
secondary
consumers
5000
primary
consumers
500,000
producers
producers
5,000,000
• A vast number of producers are required to support even a
few top level consumers.
Chemical Cycling in
Ecosystems
 Ecosystems
 Depend
on a recycling of chemical
elements.
 Biogeochemical cycles
 Are
chemical cycles in an ecosystem that
involve both biotic and abiotic components.
Learner Outcomes
 I can explain the major components of
the water, carbon, nitrogen and
phosphorus cycles and how humans
can impact each of these.
Biogeochemical Cycles
 Three key points :
 Each circuit has an
abiotic reservoir.
 A portion of chemical
cycling can rely
completely on geological
processes.
 Some chemicals require
processing before they
are available as inorganic
nutrients.
Examples of Biogeochemical
Cycles
 Carbon
 Nitrogen
 Phosphorus
 Water
Carbon Cycle
Human Impacts:
 Greenhouse Effect


Increase of
atmospheric CO2
 Combustion of
fossil fuels
 Burning of wood
from deforestation
Increase in global
temperature
Nitrogen Cycle
Human Impact:
 Cultivation—turns up soil and ↑
decomposition of organic
matter; Releases more nitrogen
 Harvesting ↓ nitrogen from
ecosystem
 Adding industrially
synthesized fertilizers to soil
has resulted in doubling
globe’s supply
 Excess nitrogen leeches
into soil and into rivers,
streams, and lakes and
ground water—
– ↑ levels are toxic to
aquatic organisms
and humans
– Algal blooms in
lakes ↑
eutrophication
Phosphorus Cycle
Human Impact:
 Sewage treatment
facilities and
fertilizers

↑ amounts of
phosphates to
aquatic systems,
causing
eutrophication of
lakes.
Water Cycle
Human Impact:
 Destruction of tropical
rain forest


Will change the amount
of water vapor in the air.
May alter local and global
weather patterns.
 To irrigate crops,
humans pump large
amounts of ground
water to the surface.
Populations
•
A population is…
Members of the same species…
 Who live in the same place
 At the same time.

Learner Outcomes:
 I can define population density and carrying
capacity.
 I can describe the three types of dispersion
patterns.
 I can differentiate between exponential
growth and logistic growth.
 I can define and identify density-dependent
and density-independent limiting factors.
Populations
•
•
The environment where a population
lives: habitat.
The role of the organism is its niche.
Populations
 Population ecologists study many
things about populations in their
habitats:
 Population size
 Population density
 Population growth
Population Density
 Population density
 Is the number of individuals of a species per unit of area or
volume.


In most cases, it is impractical or impossible to count all
individuals in a population.
In some cases, population densities are estimated by indirect
indicators, such as number of bird nests or rodent burrows.
Populations
 Populations are densest where there
are resources available.
Populations
Patterns of Dispersion
 The
dispersion pattern of a population is
the way individuals are spaced within the
population’s geographic range.
 Three types:
Clumped
 Uniform
 Random

Clumped Pattern of Dispersion

Individuals aggregate in patches.
Uniform Pattern of Dispersion

Results from interactions among the individuals of
a population.
Random Pattern of Dispersion

Individuals are spaced in a patternless,
unpredictable way.
Population Growth Models
 Two
models, the exponential growth model
and the logistic growth model, will help us
understand population growth.
 The growth rate

Is the change in population size per time
interval.
The Exponential Growth Model: The
Ideal of an Unlimited Environment
 The exponential growth model
 Describes the rate of expansion of a population
under ideal, unregulated conditions.
The Logistic Growth Model: The
Reality of a Limited Environment
 The logistic growth model
 Describes growth of an idealized population that is
slowed by limiting factors.
The Logistic Growth Model: The
Reality of a Limited Environment
 In
nature, a population may grow
exponentially for a while, but eventually
one or more environmental factors will limit
its growth.
 Population-limiting factors restrict
population growth.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
 A comparison of the logistic growth model
and the exponential growth model
Carrying Capacity
 Is the number of
individuals in a
population that the
environment can
just maintain with no
net increase or
decrease.
http://www.abc.net.au/reslib/200710/r189329_709751.jpg
Regulation of Population
Growth
 Density-Dependent Factors
 Are population-limiting factors whose effects
intensify as the population increases in size.


Food, space, disease, predators
Increase a population’s death rate and decrease
the birth rate.
Regulation of Population
Growth
 Density-independent factors
 Are population-limiting factors whose intensity is
unrelated to population density.
 Include events such as seasonal freezing, natural
disasters, unusual weather, human activity.
 In many natural populations, density-independent
factors limit population size before densitydependent factors become important.
Growth Rate
 Four influences:




Birth rate 
Death rate 
Immigration 
Emigration 
 (Birth + Immigration) – (Death +
Emigration)
Population Cycles

Some populations


Have regular boomand-bust cycles.
Boom-and-bust
cycles of the
snowshoe hare and
one of its predators,
the lynx
Communities and Ecosystems
Ch. 19
Key Properties of
Communities
 Diversity—variety of different kinds of
organisms that make it up
 Prevalent form of vegetation—
determines kinds of organisms that
will survive in the area
 Stability—ability to resist change and
return to its original species
composition after being disturbed
 Trophic level—feeding relationships
among the various species
Diversity
Which community is more diverse?
 The diversity of a
community

Is the variety of different
kinds of organisms that
make up the community.


Species richness, the
total number of different
species in the
community
Relative abundance of
the different species
Interactions in Communities
 Competition occurs when 2 or more
populations overlap in their niches
 Limiting
resources
Food
 Space
 Mates

 Generally, one will out-compete the
other
Competition in Nature


Two possible Outcomes
1. Weaker competitor becomes extinct
2. One or both species may evolve
enough to use a different set of
resources (resource partitioning)
Competition cannot operate for long
periods of time
Competitive Exclusion
Principle
 Two species cannot
coexist in a community
if their niches are
identical
Interactions in Communities
 Predation—
consumption of
one organism by
another
http://www.dldigital.com/images/z_oldimages/2002-10-d28aphid2-fr18.jpg
Predator Adaptations
 Most predators have acute senses.
 Many predators


Have adaptations such as claws, teeth, fangs, stingers, or
poison to help catch and subdue prey.
Are fast and agile.
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/H
awk_eating_prey.jpg/300px-Hawk_eating_prey.jpg
http://images.encarta.msn.com/xrefmedia/sharemed/targets/images/pho/00123/
00123ed3.jpg
Plant Defenses Against
Hebivores
www.treklens.com/.../Sweden/phot
o198584.htm
 Physical defenses
 thorns, hooks/spines
on leaves


http://en.wikipedia.org/wiki/Image:Toxic
odendron_radicans.jpg
 Chemical defenses
 Make plant
distasteful or
poisonous
Morphine from opium
poppy
Nicotine from tobacco
Poison Ivy
http://images.wildmadagascar.org/pictu
res/isalo/walking_stick0071.jpg
Animal Defenses Against
Predators
 Behavioral defenses

Alarm cries
 Distraction displays
 Cryptic coloration/shape
(camouflage)
Blend in with environment
 Asposematic coloration
 Red/black; yellow/black
Stick Insect
www.laspilitas.com/.../Monarch_butte
rfly.htm

 Mechanical/chemical
defenses

Quills, spines, and other
similar structures
 Toxins—distasteful or
poisonous
Monarch butterfly on Milkweed
Animal Defenses Against
Predators
 Mimicry—prey resembles
species that cannot be eaten
 Batesian mimicry: Imitate
color patterns or
appearance of more
dangerous/unpalatable
organisms
 Müllerian mimicry: 2
unpalatable species that
inhabit the same
community mimic each
other
Symbiotic Relationships: close relationships
between two or more organisms
Parasitism- one is harmed, one benefits.

Parasitism—specialized predator (parasite) lives on/in its
host, not killed immediately
 Endoparasitism—live inside host (tapeworms/viruses)
 Ectoparasitism—live on surface
of host (mosquitoes/aphids)
Mutualism—both partners benefit
Lichens-association b/w fungus and algae
 Bees and flowering plants
 Nitrogen-fixing bacteria and legumes

Symbiotic Relationships
 Commensalism: one individual benefits,
the other is neither helped or harmed.
 Example:
mites in human eylashes
Community Structure
 Predators can
moderate
competition among
its prey species
 Keystone species
can alter the whole
community
Disturbances in a Community
 Storms, fire, floods, droughts,
overgrazing, or detrimental human
activities:
 Remove
organisms
 Alter resource availability
 Create opportunities for new species
that have not previously occupied the
habitat
 Humans are the biggest disturbance
 Logging,
agriculture, overgrazing
Ecological Succession
 Primary succession
 Begins in a virtually lifeless area where soil has
not formed
 Lichens and mosses colonize first
 Soil gradually forms and small plants and shrubs
take root
 Secondary succession
 Occurs where an existing community has been
cleared by some disturbance that leaves soil in
tact
 Earliest plants to recolonize are often those that
grow from wind-blown or animal-borne seeds
Ecological Succession
 Tolerance to abiotic conditions
determines early species
 Competition among early species shape
the succession of an area
Mt. St. Helen 1980 Eruption
MSH80_st_helens_spirit_lake_before_may_18_1980.jpg
http://www.jqjacobs.net/photos/volcano/st_helens.html
http://denali.gsfc.nasa.gov/research/volc2/MSHreflection.gif
Mt. St. Helen
Secondary Succession

http://www.kgw.com/newslocal/stories/L_IMAGE.101688cd0b5.93.88.fa.7c.2791
3b573.jpg
Red alder disperses easily and is
capable of rapid growth on the nutrientpoor, volcanic deposits.
 A red-legged frog –one of the creatures
living in one of the dozens of ponds
created after the eruption.
 70 species of birds, including
hummingbirds, western meadowlarks
and Savannah sparrows
www.kgw.com/news-local/stories/kgw_051505_env...
www.kgw.com/news-local/stories/kgw_051505_env...
Humans are part of the Earth's
ecosystem. Human activities
can either deliberately or
inadvertently
alter the balance
of an ecosystem.
What do you Think???
How do human
activities affect the
environment?
Human impacts on the Environment
Global warming
Use of machinery by
humans seems to be
increasing CO2 levels
in the air. CO2
prevents heat from
escaping, causes
slight world wide
temperature
increases
Rising water temperatures
causes coral bleaching
Human impacts on the
environment
Deforestation
Caused by demand for wood products,
need for space, farmland, housing,
roads
 Deforestation causes
habitat fragmentation
Animals and plants are forced into
confined areas

Habitat Fragmentation
Habitat Fragmentation
Human impacts on the Environment
Ozone depletion
 Caused by aerosol chemicals called
chlorofluorocarbons (CFCs)
 CFC’s

Escape into atmosphere, reacts breaking
down the ozone (O3, a protective
atmospheric layer)

UV rays penetrate the atmosphere and
cause harm to many organisms
“HOLE” in
the ozone
(O3)
Human impacts on the environment
Invasive species (EXOTIC SPECIES)
introduced by people accidentally or
intentionally
 Can cause problems if no natural enemies are
present
Cane toad was
introduced to Australia
to control cane beetles,
pest insects that destroy
sugar cane crops
Importance of the Environment
Biodiversity = Many
different types of
organisms
 Organisms depend
upon one another
 Interfering with one
Organism can have a
Ripple effect to many
w/in the habitat
Importance of the environment
Natural resources:
Non-renewable
includes fossil fuels
(petroleum, coal)
 Renewable includes
animals, plants,
water, wind, etc.
 even
renewable
resources can run
out
Importance of the Environment
Natural resources
Renewable energy sources include wind
power, geothermal energy, ocean
currents
Pollution:
 Agricultural
 DDT
 Fertilizers
 Animal
wastes (nitrogen)
 Homes
 Strong
cleaning agents
 Industry
 Toxic
gases and wastes
 Acid rain