Transcript Populations & Communities (video #1)

Populations & Communities (video #1)
1.
Name the endangered species studied by Dr. Burk and Dr.
Jones. Briefly explain its importance in reasons why they
are trying to save it.
2. As bacteria grow under ideal conditions what is happening
in the population during the lag phase and exponential
growth phase? How is density dependent factors different
from density independent factors?
3. What example is used to show commensalism and
mutualism? (species involved)
4. How is the niche for the Great Horned Owl different from that
of a common barn owl?
5. In the final segment, Why have humans become the most
successful species on Earth?
**Write the title for each segment and FIVE statements for
each segment.
Chapter 52- Populations
Introductory Questions #1
1)
2)
3)
4)
5)
6)
7)
8)
9)
How would you define a population? What factors do you
need to consider when analyzing a population?
What are the (3) characteristic patterns usually observed
when studying a population?
Name three factors that can affect the growth rate of a
population.
How are density dependent factors different from density
independent factors? What do these factors do to a
population?
How is an r-selected species different from a k-selected
species. Give an example for each.
Explain how a type II survivorship is different from a type III.
Give an example of a type II organism.
What year is thought to be the time at which the world
population reached 1 billion? 2 billion? And 3 billion?
Which country has an age structure that appears to have
potential problems in the future?
What has been the primary cause for the population growth
rate to increase so rapidly in the last 100 years?
ECOLOGY
• The study of living organisms
and their interaction with the
nonliving environment
Historical Background
• Ecology
• Eco = “house”
ology = “study of”
• BIOTIC
ABIOTIC
Biotic & Abiotic Factors
• Biotic: living components of the
environment.
(interactions between organisms)
• Abiotic: Non-Living components of
the environment
(chemical & physical factors)
Key Environmental Issues
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Global Warming
Resource Conservation (fuel)
Water Conservation
Endangered species
Pollution
Pesticides- DDT, Rachel Carson- Silent Spring
Others ????
Ecological Concepts
• Species Diversity
• Species Number
Characteristics of Populations
• Density:
• Distribution:
• Age Structure:
• Carrying Capacity
• Mortality rate
Populations are Defined in Several Ways
• Ecologists define a population as a singlespecies group of individuals that use common
resources and are regulated by the same
environmental factors
– Individuals in a population have a high likelihood of
interacting and breeding with one another
• Researchers must define a population by
geographic boundaries appropriate to the
questions being asked
Density and Dispersion Patterns are
Important Population Variables
• Population density is the number of
individuals in a given area or volume
• It is sometimes possible to count all the
individuals in a population
– More often, density is estimated by sampling
Population Characteristics
• Density~ # of individuals per unit of area •counts
•sample size estimate
•indirect indicators
•mark-recapture
• Dispersion~ pattern of spacing
•random~ unpredictable, patternless spacing
•clumped~ patchy aggregation
•uniform~ even spacing
• One useful sampling technique for
estimating population density is the markrecapture method(See the Population Sampling Packet)
Figure 35.2A
• The dispersion pattern of a population
refers to the way individuals are spaced
within their area
– Clumped
– Uniform
– Random
Population Characteristics
• Clumped dispersion is a pattern in which
individuals are aggregated in patches
– This is the most
common
dispersion
pattern in nature
– It often results
from an unequal
distribution of
resources in the
environment
Figure 35.2B
• A uniform pattern of dispersion often results
from interactions among individuals of a
population
– Territorial behavior and competition for water
are examples of such interactions
Figure 35.2C
• Random dispersion is characterized by
individuals in a population spaced in a
patternless, unpredictable way
– Example: clams living in a mudflat
– Environmental conditions and social
interactions make random dispersion rare
Introductory Questions #1
1)
2)
3)
4)
5)
6)
7)
8)
9)
How would you define a population? What factors do you
need to consider when analyzing a population?
What are the (3) characteristic patterns usually observed
when studying a population?
Name three factors that can affect the growth rate of a
population.
How are density dependent factors different from density
independent factors? What do these factors do to a
population?
How is an r-selected species different from a k-selected
species. Give an example for each.
Explain how a type II survivorship is different from a type III.
Give an example of a type II organism.
What year is thought to be the time at which the world
population reached 1 billion? 2 billion? And 3 billion?
Which country has an age structure that appears to have
potential problems in the future?
What has been the primary cause for the population growth
rate to increase so rapidly in the last 100 years?
Idealized Models help us Understand
Population Growth
• Idealized models describe two kinds of
population growth
– Exponential growth
– Logistic growth
• Exponential growth is the accelerating
increase that occurs during a time when
growth is unregulated
• A J-shaped growth curve, described by the
equation G = rN, is typical of exponential
growth
– G = the population growth rate
– r = the intrinsic rate of increase, or an organism's
maximum capacity to reproduce
– **r = (birth rate – death rate) + immigration rate –
emigration rate)
– N = the population size
Population Growth Models
• Exponential model (red)
• idealized population in an
unlimited environment (J-curve);
r-selected species (r=per capita
growth rate)
• Logistic model (blue)
•carrying capacity (K): maximum
population size that a particular
environment can support (S-curve); Kselected species
Biotic Potential (rmax)
Figure 35.3A
• The equation G = rN(K - N)/K describes a
logistic growth curve
– K = carrying capacity
– The term
(K - N)/K
accounts
for the
leveling
off of the
curve
Figure 35.3C
• The logistic growth model predicts that
– a population's growth rate will be low when
the population size is either small or large
– a population’s growth rate will be highest
when the population is at an intermediate
level relative to the carrying capacity
• Logistic growth is slowed by populationlimiting factors
– It tends to level off at
carrying capacity
– Carrying capacity
is the maximum
population size
that an environment
can support at a
particular time
with no degradation
to the habitat
Figure 35.3B
Density Controls
Age Structure Diagrams
• Provides the following information:
- Percentage of age groups in a population
Pre-reproductive
Reproductive
Post-Reproductive
(0 -15 years)
(15-44 years)
(45yrs - death)
- Number of males and females
- Helps to predict future growth
- Can show if the population is increasing,
decreasing, or remaining constant.
- Shape Matters: pyramid vs. tapered base (funnel)
- Indicates social conditions
RAPID GROWTH
SLOW GROWTH
ZERO GROWTH/DECREASE
Kenya
United States
Italy
Male
Female
Male
Female
Ages 45+
Ages 45+
Ages 15–44
Ages 15–44
Under
15
Percent of population
Male
Female
Under
15
Percent of population
Percent of population
Figure 35.9B
Life Tables Track Mortality and
Survivorship in Populations
• Life tables and survivorship curves predict
an individual's statistical chance of dying or
surviving during each interval in its life
• Life tables predict how long, on average, an
individual of a given age can expect to live
– This table was compiled using 1995 data from
the U.S. Centers for Disease Control
Table 35.6
• Population ecologists have adopted this technique,
constructing life tables for various plant and animal
species
• Type I Survivorship: K-selected species (humans)
-live long, few offspring (maternal care)
-mortality is later in life
• Type II Survivorship: intermediate (Plants, lizards)
-Mortality is equal across all age groups
• Type III Survivorship: r-selected species
-Mortality is high right after birth
-small body, no parental care
-High production of offspring
(weeds, fish, and asexual reproducers)
• Survivorship curves plot the proportion of
individuals alive at each age
• Three types of survivorship curves reflect
important species differences in life
history
Figure 35.6
Life Histories
• An organism's life history is the series of
events from birth through reproduction to
death
• Life history traits include
– the age at which reproduction first occurs
– the frequency of reproduction
– the number of offspring
– the amount of parental care given
– the energy cost of reproduction
R-Selected Species
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High Population Growth Rate (r=growth rate)
Small body
Early maturation
Short lifespan
Large broods
Little or no parental care
Considered to be opportunistic
Found in environments that are temporary,
unpredictable, and variable
• Low Survivorship; die early in life
Ex. Weeds, Dandelions, other asexual reproducers
K-Selected Species
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Number of individuals is near carrying capacity (K)
Large body
Low reproductive rate
Produce few offspring
Long lifespan
Development is slow (late maturation)
Parental care & protection of the young
Found in relatively stable environments
Ex. Birds & Mammals
Some Populations have “Boomand-Bust" Cycles
• Some populations go through boom-andbust cycles of growth and decline
• Example: the population cycles of the lynx
and the snowshoe hare
– The lynx is one of the main predators of the
snowshoe hare in the far northern forests of
Canada and Alaska
Predator/Prey Interactions & the
Effects on the Population
Intrinsic Pattern of Growth
• Field studies of
the song
sparrow have
demonstrated
that birth rates
may decline as
a limited food
supply is divided
among more
and more
individuals
Figure 35.4A
• Abiotic factors may limit many natural
populations
– Aphids show
exponential
growth in the
spring and
then rapidly
die off when
the climate
becomes hot
and dry in the
summer
Figure 35.4B
THE HUMAN POPULATION
• The human population as a whole has doubled
three times in the last three centuries
• The human population now stands at about 6.1
billion and may reach 9.3 billion by the year 2050
• Most of the increase is due to improved health
and technology and an overall decline in the
death rate
• The birth rate has actually decreased in the last
200 years.
• Growth rate = 1-2% per year
• The history of human population growth
Figure 35.8A
Human Population Growth
• 10,700 babies/hour
Population Explosions
Populations & Communities (video #1)
1.
Name the endangered species studied by Dr. Burk and Dr.
Jones. Briefly explain its importance in reasons why they
are trying to save it.
2. As bacteria grow under ideal conditions what is happening
in the population during the lag phase and exponential
growth phase? How is density dependent factors different
from density independent factors?
3. What example is used to show commensalism and
mutualism? (species involved)
4. How is the niche for the Great Horned Owl different from that
of a common barn owl?
5. In the final segment, Why have humans become the most
successful species on Earth?
**Write the title for each segment and FIVE statements for
each segment.
The End
Video #2: “Curtain Calls”
(see pg. 1162)
• Write 15 statements from the video.
• Look for examples of:
– Mimicry (Mullerian & Batesian)
– Cryptic coloration (camouflage)
– Warning coloration
Ch. 53 & 54 – Ecosystems & the Biosphere
(video # )
1.
What organism is used in the video by D. Zembal to show
how an endangered species struggles in a particular
ecosystem. Name the type of ecosystem discussed in the
first segment of the video that provides an example of a
complex food chain. What organisms are involved?
2. What is a “Controlled Burn” and how does it help an
ecosystem? Which two elements are recycled and
discussed in the video?
3. What effect has global weather patterns had on our
climate? Which elevations are explored by Dr. Poth? Name
the type of organisms at each elevation and ecosystem
mentioned?
**Write the title for each segment and FIVE statements for
each segment.
The Human Factor (video # )
1. What are the effects of global warming on the
Earth’s environment? How do we know if this is
really happening?
2. The second segment touches on alternative
sources of fuel. What are some possible solutions
to our dependency on carbon fuels?
3. How does Dr. Frankenberger suggest we clean up
toxic wastes in our environment? What does he
use?
4. How does the second law of thermodynamics
relate to the use of world resources and food
supplies?
**Write the title for each segment and FIVE statements
for each segment.