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 #11) How would you define a population? What factors do you

need to consider when analyzing a population?2) What are the (3) characteristic patterns usually observed

when studying a population?3) Name three factors that can affect the growth rate of a

population. 4) How are density dependent factors different from density

independent factors? What do these factors do to a population?

5) How is an r-selected species different from a k-selected species. Give an example for each.

6) Explain how a type II survivorship is different from a type III. Give an example of a type II organism.

7) What year is thought to be the time at which the world population reached 1 billion? 2 billion? And 3 billion?

8) Which country has an age structure that appears to have potential problems in the future?

9) 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• 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

• Ecologists define a population as a single-species 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

Populations are Defined in Several Ways

• 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

Density and Dispersion Patterns are Important Population Variables

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 mark-recapture 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 #11) How would you define a population? What factors do you

need to consider when analyzing a population?2) What are the (3) characteristic patterns usually observed

when studying a population?3) Name three factors that can affect the growth rate of a

population. 4) How are density dependent factors different from density

independent factors? What do these factors do to a population?

5) How is an r-selected species different from a k-selected species. Give an example for each.

6) Explain how a type II survivorship is different from a type III. Give an example of a type II organism.

7) What year is thought to be the time at which the world population reached 1 billion? 2 billion? And 3 billion?

8) Which country has an age structure that appears to have potential problems in the future?

9) What has been the primary cause for the population growth rate to increase so rapidly in the last 100 years?

• Idealized models describe two kinds of population growth– Exponential growth – Logistic growth

Idealized Models help us Understand Population 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); K-selected species

Figure 35.3A

Biotic Potential (rmax)

• 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 population-limiting 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 populationPre-reproductive (0 -15 years)

Reproductive (15-44 years)Post-Reproductive (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

Figure 35.9B

RAPID GROWTH

Kenya

Male Female

Percent of population Percent of population Percent of population

SLOW GROWTH

United States

Male Female

ZERO GROWTH/DECREASE

Italy

Male Female

Ages 45+

Ages 15–44

Under15

Under15

Ages 45+

Ages 15–44

• 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

Life Tables Track Mortality and Survivorship in Populations

– 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

• 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

Life Histories

R-Selected Species• 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• 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 go through boom-and-bust 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

Some Populations have “Boom-and-Bust" Cycles

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 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 HUMAN POPULATION

• 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.