Populations

1
Populations

• One of the major themes of life is
• Interdependence, which states that
• organisms are dependent on one
• another their envt

• ECOLOGY The study of the
• interactions of living organisms w/
• one another and w/ their envt

2
I. Introduction A. Groups of Organisms

• Population group of organisms of the
• same species living in a particular place
• at a particular time.
• a. Species a group of organisms that
• look alike, are genetically similar,
• can reproduce
• b. In biology, these organisms will
• interbreed mate w/in the population
• c. Examples

3
(No Transcript)
4

• Community Different populations that live
• in the same area interact with one another
• --Example Marine community

5

• Biome/Ecosystem Communities of living things
  interacting with each other AND with their
  physical envt.
• -- Example Tropical Rainforest, Desert,
  Savannah, Tundra

6
(No Transcript)
7
4. Biosphere All the life supportive envts
and organisms on this planet.
8
B. Three important characteristics of every
population 1. geographic distribution
(i.e. the area being inhabited)
2. size density ( of organisms in an
area and how are they dispersed)
3. growth rate (i.e. do they grow, stay the
same, or decrease in size)
? growth 1. when birth gt death
2. immigration move into pop.
? decrease 1. when birth lt death
2. emigration move out of pop.
9
(No Transcript)
10
C. Organisms in a Population are Dispersed ?
Dispersion How individuals w/in Pop. are
arranged
1. Clumped Individuals are bunched
together into clusters
11
2. Even/Uniform Individuals are located at
regular intervals
12
3. Random location is self-determined
13
II. Predicting population growth

• Considers Carrying Capacity The Pop. size
• that an envt can sustain. Affected by
  predators,
• prey, resources, etc.
• ? Pop. lt carrying capacity rapid growth
• ? Pop. reaches carrying capacity growth
• stops (death rate birth rate)
• ? Two basic types of growth

14
a. Exponential growth curve - unlimited
resources - predators are few or
non-existent
b. Logistic model - declining resources
(i.e. competition) - increases in of predators
15
(No Transcript)
16

• Limits to Growth within a Population
• Limiting resources growth depends on
• those resources needed for survival
• (ex. food, water, shelter)
• Limiting Factors factors that cause
• population growth to stop by depleting
• limiting resources
• (ex. Disease, hunting, natural disaster,
• deforestation, climate)

17
III. Types of Populations

• r-strategists Exhibit exponential
• growth when conditions allow
• (Ex cockroaches, fruit flies)

• K-strategists Population is usually
• near the carrying capacity
• (Ex whales, humans)

18
(No Transcript)
19
IV. Population Genetics How Populations Evolve

• There are a variety of factors that affect
• how a population evolves (Hardy-Wein.)

• Mutations Very slow, affects are seen over
• long period of time (source of variations)
• Ex cancer, bacteria strains

2. Gene Flow Migration, movt in/out of Pop.
3. Non-random Mating (selection) inbreeding
4. Genetic Drift certain genes only found in
1 or 2 indiv. (small Pop. affected most)
5. Natural selection survival of the fittest
-- strongest individuals will pass on traits
20
COMMUNITIES
What is Community Ecology? ?The study of how
populations of organisms (living in a small
area) interact with each other
21
I. Characteristics of Communities
A. Community Interactions ? Populations
of organisms often interact w/ each
other in complex ways.

• Predator-Prey Interaction
• - Predation one organism (predator)
• captures feeds on another (prey)

2. Competition when organisms compete with
each other for resources (food/shelter)
22
3. Symbiosis any relationship in which two
organisms live closely together. Four types

1. mutualism -

when both organisms benefit
when one benefits and the other is unaffected
b. commensalism -
c. amensalism -
when one is harmed the the other is unaffected
d. parasitism -
when one benefits the other is harmed
23
effects on organism 2
BENEFIT HARM NO EFFECT
BENEFIT
HARM
NO EFFECT
predation/ parasitism
mutualism
commensalism
effects on organism 1
predation/ parasitism
competition
amensalism
xxxxxxxxxxx
commensalism
amensalism
24
B. The Ecological Niche

• The ecological position of a species in a
• community. The role it plays in the
• community larger ecosystem
• (ex. An animals place in the food web)

2. Includes the physical and biological
conditions needed to survive. (ex. food
source, temp, live near water)
25
Ecosystems (a.k.a. Biomes)
A Community of living things together WITH the
physical envt. (how populations interact with
each other AND their environment)
26
(No Transcript)
27
(No Transcript)
28
I. What is an Ecosystem?

• ? The living organisms are known as biotic
  factors
• The physical (i.e. non-living) aspects are called
  abiotic factors (e.g. water, soil, climate,
  temp.)
• Together, these factors determine the survival,
  growth productivity of organisms the
  ecosystem
• ? Organisms create a habitat within an ecosystem

29
II. Energy Flow

• All living things require energy for metabolism
  and growth
• The flow of NRG determines what kind how many
  
• organisms an ecosystem can support

• Producers (a.k.a. Autotrophs)
• 1. The primary source of NRG is the sun
  
• 2. All life depends on organisms that can
  capture
• solar NRG and convert it to chemical
  NRG (i.e.
• glucose) during photosynthesis
• 3. Thus, they produce their own NRG and
  food
• for other organisms

B. Consumers (a.k.a. Heterotrophs) ?
organisms that must rely on other organisms for
food and NRG
30
PHOTOSYNTHESIS
Sun 6CO2 6H2O ? C6H12O6 6O2
31

• Trophic Levels
• 1. a group of organisms that obtain their NRG
• from a common source
• 2. NRG moves from one level to another
• 3. There are five levels

32

• Lowest level Primary producers
• (a.k.a. photosynthesizers)

Plants
Algae
Some bacteria
33

• Level two Primary consumers
• ? Eat the primary consumers
• ? known as Herbivores

Grasshoppers
Caterpillars
Geese
Mice
Cows
34

• Level three Secondary consumers
• ? Eat the primary consumers
• ? known as Carnivores eat the herbivores

35

• Level Four Tertiary consumers
• a. Top carnivores eat all other animals

b. Omnivores eat plants animals
36
5. Level Five Detritivores (a.k.a. decomposers)
- a class of consumers that obtain their NRG
from the organic wastes dead bodies
produced at all trophic levels.
Worms
Fungi
Bacteria
37
Decomposers worms, fungi, bacteria help to
recycle nutrients and elements
38
II. Energy Flow Through an Ecosystem ?
Exploring Feeding Relationships
A. Food Webs a. interconnected network of
food chains that traces the directional
flow of NRG in an eco. b. animals feed at
several levels, thus NRG doesnt flow in
straight paths.
39
Food Web
40
B. Ecological Pyramids

• Diagrams that show the relative amounts
• of NRG and matter contained within
• each trophic level.
• 2. Three types of pyramids

41
ENERGY PYRAMIDS
1. organisms use NRG to metabolize, thus, much of
their NRG is lost as heat during biochemical
reactions (cant be used)
2. 10 RULE only 10 of the NRG available at one
trophic level is transferred to organisms at the
next level.
42
Energy Loss
43
Biomass Pyramid (total amount of living
tissue at each level)
44
Pyramid of Numbers (shows the number of
individual organisms at each troiphic level)
45

• Ecosystem Cycles
• ? in addition to NRG, organisms need
  other
• inorganic substances to fxn

• Although NRG flows in one direction
• carbon other inorganic substances are
• constantly recycle

• Biochemical cycle substances pass
• from nonliving envt (e.g. soil,
  atmosphere)
• to living things, back to nonliving envt

• Four critical substances needed to sustain
• health of an ecosystem C, N, P, H2O

46
A. The Water Cycle
1. Water vapor condenses and falls as
precipitation 2. Some seeps into soil and becomes
ground water (below surface) 3. Most runs-off
surface back to oceans lakes 4 Sun heats
oceans lakes and water evaporates back into the
atmosphere (transpiration the
evaporation of water from plants)
47

• The Carbon Cycle
• carbon forms the backbone of all
  organisms

1. How is CO2 taken out of atmosphere? ?
Photosynthesis ? CO2 is used by plants
algae to build GLUCOSE ? Consumers will get
their carbon by eating other
organisms or their remains
2. How is C returned to the atmosphere as CO2?

• Cellular Respiration by organisms
• 6O2 C6H12O6 ? 6CO2 6H2O

b. Combustion -- dead organisms decompose
and form oil coal (i.e. fossil fuels)
undergroundhumans BURN -- humans also cut
down and burn forests
c. Volcanic activity
48
The Carbon Cycle
49
C. The Nitrogen Cycle 78 of atmosphere
is N2, but also in DNA, RNA, proteins
1. Though abundant, it cant be used as a gas
from the air. Needs to be converted into a usable
form (i.e. ammonia, NH3), in a process called,
nitrogen fixation ? done by bacteria in
roots of plants and in soil
2. When organisms decompose, nitrogen is also put
into the soil as ammonia, which can be used
by producers
3. Nitrification ammonia is converted into
nitrates (NO3-) by different bacteria in
soil
4. Denitrification nitrates are converted back
into nitrogen gas which is released back
into atmosphere
50
The Nitrogen Cycle
51
D. The Phosphorus Cycle (for DNA/RNA)
different b/c atmosphere doesnt play a role

• On Land
• ? Phophorus exists primarily as phosphate
  (PO43-)
• found in soil deposits, which can be
  absorbed by
• plants then eaten by consumers
• ? Consumers decompose release phosphate
  back
• into ground to be taken up by producers

2. In Ocean ? Phosphate also found in
ocean sediment. When erosion from
land occurs or these sediments break
down, phosphate released into ocean dissolved.
? Then taken up by algae, eaten by
consumers, and excreted back into
ocean
52
The Phosphorous Cycle
53
IV. Nutrient Limitations

• The 4 cycles are imported b/c they provide
  ecosystem
• w/ nutrients
• Primary productivity the rate at which
  producers use
• these nutrients to create organic matter.
• Short supply of any nutrient will slow growth
  and p
• productivity (why farmers use fertilizers)

? Aquatic systems may get too much nutrient
leading to build up of algae, known as an
algal bloom, which can be bad if not enough
consumer to keep in equilibrium
54
(No Transcript)
55
Human Impact on the BIOSPHERE
56

• Acid Rain The acidified precipitation
• that results when sulfur-rich smoke
• combines w/ water vapor to produce
• sulfuric acid
• ? The smoke is a result of power plants
• burning fossil fuels (coal oil),
• as well as car exhaust

1. Ozone Depletion

a. Ozone (O3) the layer of the
atmosphere that protects living
organisms from harmful UV light
57

1. Ozone depletion results from CFC breakdown

• CFCs (ChloroFluoroCarbons) molecules
• containing chlorine, fluorine, and carbon
• Sources

Aerosols
Coolant systems
Foaming Agents
58

• When CFCs are released into the atmosphere,
• UV radiation breaks the bonds, thus releasing
• chlorine atoms which break down ozone

59
3. Global Warming

• The Greenhouse Effect
• The warming of the atmosphere due to
• greenhouse gases (CO2, methane, nitrous
  oxide)

• Short wave solar NRG pass thru atmosphere
• and hits earth
• Some is absorbed some is reflected back into
• the atmosphere as long wave radiation
• This radiation cant pass thru clouds or CO2
• It is absorbed or reradiated back to earth
• Thus, earth is heated

• This is similar to a greenhouse

60
(No Transcript)
61
a. The greenhouse effect is enhanced by the
burning of fossil fuels and vegetation, which
releases C into the atmosphere. The C
combines with O2 to form CO2

1. CO2 concentration and thus global temp has
   steadily increased over the last 150 years
   (industrial revolution)

c. Future concerns?

• Sea level rising (due to melting of glaciers and
  ice caps)
• Changes in weather patterns (severe weather)

62
II. Ecosystem Damage
A. Daily Environmental Damage

• Chemical Pollution (in air, lakes,
• oceans) kills wildlife aquatic life

63
2. Agricultural Chemicals

• pesticides (DDT), herbicides, fertilizers

• Biological Magnification
• ? Chemicals breakdown
• slowly in envt and
• collect in animal tissues
• ? Concentration of
• chemical is increased
• as it passes up thru
• the food chain

64
3. Consumption/Destruction of resources

• Species extinction due to habitat loss (ex.
  deforestation
• Loss of topsoil due to overgrazing
• Ground water
• 1. Loss due to watering lawns, leaky faucets
• 2. Pollution b/c of improper chemical waste
  disposal

4. Human Population a. possibly the single
greatest threat b. Its continued exponential
growth will cause an increase in
waste, depletion of resources and habitat c.
however, new technology is allowing for better
sanitation, recycling, medical care,
etc.
65
III. Environmental Solutions

• Reduce global pollution
• 1. Stop CFC production
• 2. Restricted use of DDT and asbestos in U.S.
• 3. Reduce air pollution by decreasing
• emissions of CO2, sulfur dioxide, soot
• 4. Better sewage facilities
• 5. Conserve energy (car pooling)
• 6. Recycle