• Make a connection between Easter and
the movie “Night at the Museum” with
chapter 8 (populations)
Do you know where it is?
Easter Island
*Formed from volcanic eruptions
*64 sq miles
*2300 miles west of Chile
Easter Island Story
•
•
•
•
First inhabitants – 700 AD
7000-9000 people around 1500’s
1722, Europeans landed – 2500 people
What happened?
• End of Easter Island – YouTube
• http://www.youtube.com/watch?v=gSjZp_cvqY
REINDEER ON
ST. MATTHEW ISLAND
Oh Deer!
http://www.shodor.org/interactiv
ate/activities/
Populations
A. Characteristics of a population
(1) size (number of indiv.)
(2) density (spatial)
(3) dispersion (spatial pattern)
(4) age distribution
Population
B. Measuring population size, density,
distribution, etc.
1. Count vs. Sampling
2. Sampling
a. Quadrats
b. Transects
a. Line
b. Belt
c. Mark-recapture
Quadrats - % Cover and #
Random
Along transect
Line Transect – Presence/Absence
Belt Transect
Number of individuals
Presence/Absence and Abundance
Distance (m)
C. Dispersion Patterns of Organisms
Fig. 8-2 p. 161
Creosote bush – even dispersion
Penguins – Even or Uniform Distribution
D. Population Dynamics
Changes in the characteristics of a
population, occur in response to
(1) environmental stress
(2) changes in environmental
conditions
1. Exponential Growth
2. Logistic Population Growth
Fig. 8-4, p. 163
Population Dynamics
3. Carrying capacity - maximum population
of a particular species that a given habitat
can support over a given period of time.
4. Biotic potential (intrinsic rate of
increase [r]) = births – deaths
 Population size =
births – deaths + immigration – emigration
ZPG = Zero population growth
5. Environmental resistance - all factors
that limit pop growth in nature
Fig. 8-3, p. 162
Logistic vs Exponential Growth
Logistic Growth of Sheep
Population
Number of sheep (millions)
2.0
1.5
1.0
.5
1800
1825
1850
1875
Year
1900
1925
Fig. 8-5, p. 163
When Population Size Exceeds
Carrying Capacity
• Overshoots
• Reproductive time lag
• Diebacks (crashes)
Exponential Growth, Overshoot and
Population Crash of Reindeer
Number of reindeer
2,000
1,500
1,000
500
1910
1920
1930
Year
1940
1950
Fig. 8-6, p. 164
6. Minimum Viable Population
(MVP) - the
smallest
possible size
at which a
biological
population can
exist without
facing
extinction
E. Reproductive Patterns and Survival
1. Asexual reproduction – clones
Sexual reproduction – sex cells
Timing of reproduction
2. Semelparous reproduce once and
-
die; usually short-lived but salmon and
agave
3. Iteroparous - reproduce many times;
usually long-lived
Positions of r-selected and K-selected
Species on Population Growth Curve
Number of individuals
Carrying capacity
K
K species;
experience
K selection
r species;
experience
r selection
Time
Fig. 8-9, p. 166
4.
r-Selected Species
cockroach
dandelion
Many small offspring
Little or no parental care and protection of offspring
Early reproductive age
Most offspring die before reaching reproductive age
Small adults
Adapted to unstable climate and environmental
conditions
High population growth rate (r)
Population size fluctuates wildly above and below
carrying capacity (K)
Generalist niche
Low ability to compete
Early successional species
Opportunists
Fig. 8-10a, p. 167
5.
K-Selected Species
elephant
saguaro
Fewer, larger offspring
High parental care and protection of offspring
Later reproductive age
Most offspring survive to reproductive age
Larger adults
Adapted to stable climate and environmental
conditions
Lower population growth rate (r)
Population size fairly stable and usually close
to carrying capacity (K)
Specialist niche
High ability to compete
Late successional species
Competitor species
Figure 8-10b, p. 167
6. Survivorship Curves
• late loss or Type I
(usually K–
strategists), in which
high mortality is late
in life
• constant loss or
Type II (such as
songbirds), in which
mortality is about the
same for any age;
• early loss or Type
III (usually r–
strategists), in which
high mortality is early
in life.
Age
Fig.8-11, p. 167
F. Limitations on Population Size
1. Carrying capacity
2. Density-dependent controls –
greater effect on population as density
increases. e.g. competition, predation,
disease, parasitism
3. Density-independent controls –
affect population’s size regardless of density
e.g. flood, hurricane, drought, fire, pesticide,
habitat destruction
4. The Role of Predation in Controlling
Population Size
a. Predator-prey cycles
b.Top-down control
c. Bottom-up control
Population size (thousands)
160
140
Hare
120
Lynx
100
80
60
40
20
0
1845
1855
1865
1875
1885
1895
Year
1905
1915
1925
Fig. 8-8, p. 165
1935
Rabbits and Wolves Simulation
•
•
•
•
Get into groups of 2 people
Log into a computer
Go the simulation website
Answer questions on worksheet
G. Natural Population Curves
/chaotic
Fig. 8-7 p. 164
H. Conservation Biology
Conservation biology is the interdisciplinary science that
deals with problems of maintaining Earth's biodiversity,
including genetic, species, and ecosystem components of
life.
• conservation involves the sensible use of natural resources by
humans;
• three underlying principles:
- biodiversity and ecological integrity are useful and necessary for life
and should not be reduced by human activity;
- humans should not cause or hasten premature extinction of
populations and species;
- the best way to preserve biodiversity and ecological integrity is to
protect intact intact ecosystems and sufficient habitat.
© Brooks/Cole Publishing Company / ITP
Conservation Biology
1. Habitat fragmentation is the process by which
human activity breaks natural ecosystems into
smaller and smaller pieces of land called habitat
fragments.
• one concern is whether remaining habitat is of
sufficient size and quality to maintain viable populations
of wild species;
• large predators, such as grizzly bears, and migratory
species, such as bison, require large expanses of
continuous habitat;
• habitat fragments are often compared to islands, and
principles of island biogeography are often applied in
habitat conservation.
© Brooks/Cole Publishing Company / ITP
I. Human Impacts on Ecosystems
• Habitat degradation and fragmentation
• Simplifying natural systems
(monocultures)
• Wasting Earth’s primary productivity
• Genetic resistance
• Eliminating predators
• Introducing non-native species
• Overharvesting renewable resources
• Interfering with cycling and flows in
ecosystems
Human Impacts on Ecosystems
Some principles for more sustainable lifestyles:
• we are part of, not apart from, Earth's dynamic web of
life;
• our lives, lifestyles, and economies are dependent on
the sun and earth;
• we never do merely one thing;
• everything is connected to everything else; were are all
in it together.
According to environmentalist David Brower we need to
focus on "global CPR –– that's conservation, preservation,
and restoration".
© Brooks/Cole Publishing Company / ITP
Human Footprint on Earth’s Land Surface
Fig. 8-12, p. 169
I. Four Principles of Sustainability
PRINCIPLES
OF
SUSTAINABILITY
Fig. 8-13, p. 170
J. Ecosystem Restoration
Can we restore damaged ecosystems?
• yes, in some cases; but prevention is easier;
• natural restoration is slow relative to human life spans;
• active restoration can repair and protect ecosystems,
but generally with considerable effort and expense;
• example: in Sacramento, California, rancher Jim
Callender restored a wetland by reshaping land and
handplanting native plants; man of the native plants
and animals are now thriving there;
• restoration requires solid understanding of ecology;
• it is not possible to undo all ecological harm, e.g., we
can't foster recovery of an extinct species.
© Brooks/Cole Publishing Company / ITP