Chapter 3 Communities, Biomes, and Ecosystems 3.1 Community Ecology A biological community is a group of interacting populations that occupy the same

Chapter 3 Communities, Biomes, and Ecosystems

3.1 Community Ecology A biological

community is a group of interacting populations that occupy the same area at the same time

Communities Organisms rely on one another to

survive Abiotic factors affect communities and

the organisms in them Organisms adapt to the conditions they

live in Cactus retaining water in the harsh

climate of a desert Depending on which factors are present,

organisms can survive in one ecosystem, but not others

Limiting Factors Any abiotic or biotic factor that limits

the numbers, reproduction, or distribution of organisms Includes sunlight, temperature, climate,

water, nutrients, fire, soil chemistry, space, and other living things

How would temperature be a limiting factor for polar bears?

Range of Tolerance The upper and lower

limits that define the conditions in which an organism can survive Ideal water temp for

steelhead trout is between 9°C and 25°C

The ability of an organism to survive in certain abiotic or biotic factors is called tolerance

Ecological Succession The living and nonliving parts of an ecosystem

change over a period of time Forest fire

The changes that take place in a community as it gets older is called SUCCESSION

Succession Succession happens SLOWLY! So it can

be hard to see happening.

Primary Succession

occurs at an area of NEWLY EXPOSED rock (no soil) that has never been occupied by any living things (biotic factors)

Pioneer Species Lichens – a combination of fungus and

algae Lichens begin to grow on the bare rock Since they are the first organisms to

appear, they are called pioneer species

Pioneer species help to create soil by secreting acids that break down the rock

Climax Communities A mature community eventually

develops from bare rock Climax Community – the stable,

mature community that results when there is little change in the composition of species

It is the final stage of succession in a community, however, because of ecological disturbances, climax communities are unlikely to occur

Secondary Succession Occurs when a community has been

removed due to fire, flood, windstorm, etc.

New species may begin to occupy the habitat

Over time, the species belonging to the mature community may return

Secondary Succession The orderly and predictable change that takes

place after a community of organisms has been removed, but the soil has remained intact.

Chapter 4Population Ecology

4.1 Population Dynamics Populations of

species are described by density, spatial distribution, and growth rate

Population Density – the number of organisms per unit area

Spatial Distribution Dispersion – the pattern of spacing of a

population within an area Uniform, clumped groups, or random

One primary factor in the pattern is availability of resources

Population Range No population, not even humans,

occupies all habitats in the biosphere A species may not be able to expand it

population range because it cannot survive the abiotic or biotic conditions found in the expanded range Abiotic conditions – temperature, rainfall,

sunlight, humidity level Biotic conditions – predators, competitors,

parasites

Population Limiting Factors Factors that keep a population from

continuing to increase Density-independent Density-dependent

Population Limiting Factors

Density-Independent

any factor that does not depend on the number of members in the population

Usually abiotic natural events like the

weather (drought, flooding, etc.)

human interference

Density-Dependent

any factor that depends on the number of members in a population

Usually biotic Competition – density is

high, resources are low Disease – density is high Parasites – density is high

Population Growth Rate Explains how fast a given population

grows Emigration – number of individuals

moving away from a population Immigration – number of individuals

moving into a population Most populations remain the same size

from year to year

Population Growth Rate A population stops increasing when the

number of births is less than the number of deaths, or when emigration (moving out) exceeds immigration (moving in)

Carrying Capacity Maximum number of species an

environment can support for the long term

Limited by energy, water, oxygen,

Reproductive Patterns Species of organisms vary in the

number of births per reproduction cycle, the age that reproduction begins, and in the life span of the organisms

Plants and animals are placed into groups based on their reproductive factors R-strategists K-strategists

Reproductive PatternsR-Strategists

Rate strategy Live in an environment

that fluctuate Usually small organisms

(mice, fruit fly) Short life spans, produce

many offspring Usually controlled by

density-independent factors

STRATEGY: produce as many offspring as possible in a short period of time

K-Strategists Carrying-capacity Live in environments that

are predictable Larger organisms

(elephant) Long life span, produce few

offspring Controlled by density-

dependent factors STRATEGY: produce fewer

offspring that have a better chance of living

4.2 Human Population Demography: the study of human

population size, density, distribution, movement, and birth and death rates

Advances For years, environmental conditions kept

the human population size below carrying capacity

Humans have altered the environment to change the carrying capacity

Advances Agricultural

advances Domestication of

animals Technology Medicine Improvements in

shelter

Human Population Growth Rate Although the

population is still growing, the growth rate has slowed

Trends in Human Population Growth Can be altered by war and disease Demographic Transition – change in

population from high birth/death rates to low birth/death rates

Zero Population Growth (ZPG) when births

plus immigration = deaths plus emigration The population has

stopped growing because births and deaths occur at the same rate

Human Carrying Capacity Scientists are

concerned about the population reaching or exceeding the carrying capacity

Resources from the biosphere used by each person must also be limited

1. A2. B3. C4. D

0% 0%0%0%

A. emigration

B. imitation

C. immigration

D. migration

Population EcologyChapter 4

Chapter Diagnostic Questions

What term is used to describe the number ofindividuals moving into a population?

1. A2. B3. C4. D

0% 0%0%0%



B. number of organisms in an area

C. characteristics of a population

D. manner in which a population grows

A. pattern of spacing of a population in an area

What is population density?

1. A2. B3. C4. D

0% 0%0%0%



A. when birth rate equals death rate

B. when death rate exceeds birth rate

C. when birth rate exceeds death rate

D. when there are zero births

When does zero population growth occur?

1. A2. B3. C4. D

0% 0%0%0%


A. disease

B. fire

C. flooding

D. weather

4.1 Formative Questions

Which is a density-dependent factor?

1. A2. B3. C4. D

0% 0%0%0%


A. competition

B. extreme cold

C. parasites

D. predation


Which is a density-independent factor?

1. A2. B3. C4. D

0% 0%0%0%


A. emigration

B. predation

C. available nutrients

D. extreme temperatures


Which factor can limit the carrying capacity of a population?

1. A2. B3. C4. D

0% 0%0%0%



A. bioinformatics

B. demography

C. ecology

D. ethnography

The study of the size, density, distribution,

and movement of the human population is _______.

1. A2. B3. C4. D0% 0%0%0%



A. decreased agriculture

B. famine and wars

C. setbacks in medicine

D. voluntary populationcontrol

Which is a primary reason for the decline in the percent growth of the human population after 1962?

1. A2. B3. C4. D

0% 0%0%0%



A. CDC

B. HPG

C. PGR

D. ZPG

What will happen to the human population

when the birthrate equals the death rate?

1. A2. B3. C4. D0% 0%0%0%


A. exponential

B. spatial

C. genetic

D. logistic

Chapter Assessment Questions

Which type of population growth model does this graph represent?

1. A2. B3. C4. D0% 0%0%0%


A. India has very little land for

farming.

B. Germany is smaller per acre than

the United States.

C. More land is used to support an

individual in the United States.

D. A person in Indonesia requires

more

land than a person in Brazil.


Based on the information in the graph, infer which statement accurately represents the information provided.

Use the graph to explain the growth of the

mice population.



Answer: If two adult mice breed and produce a litterand their offspring survive to breed, then the population grows slowly at first. This slow growth is defined as the lag phase. The rate of population growth begins to increase rapidly because the total number of organisms that are able to reproduce has increased. Exponential growth occurs when the growth rate is proportional to the size of the population. All populations grow exponentially until some limiting factor slows the population’s growth.



1. A2. B3. C4. D

0% 0%0%0%


A. 0.23

B. 23

C. 230

D. 2300

Standardized Test Practice

An ecologist estimates a population density of 2.3 lemmings per square meter of tundra. What would be the approximate number of lemmings over 1000 square meters of tundra?

1. A2. B3. C4. D

0% 0%0%0%



A. density

B. dispersion

C. logistic spacing

D. spatial distribution

The ecologist finds that over a 1000m2 plot of tundra, lemmings tend to concentrate in clumps in drier areas. What is the term for this pattern of spacing?

1. A2. B3. C4. D

0% 0%0%0%



A. It is density-dependent.B. It is limited by biotic

factors.C. It has a limited spatial

distribution.D. It is randomly dispersed

in the environment.

Brine shrimp are able to survive only in certain lakes that have a very high salt concentration. Which is the correct population characteristic of brine shrimp?

1. A2. B3. C4. D0% 0%0%0%



Why does the population growth level off at 10,000?

A. Biotic factors have made survival difficult.

B. The population has reached its carrying capacity.

C. Density-independent factors have slowed the growth of the population.

D. Immigration into the population has reached the maximum limit.

1. A2. B3. C4. D

0% 0%0%0%



Which organism is the best example of a k-strategist?

A. wolf

B. grasshopper

C. rabbit

D. whale

Population Ecology

Glencoe Biology Transparencies

Chapter 4

Population Ecology

Image Bank

Chapter 4

population density

dispersion

density-independent

factor

density-dependent

factor

population growth

rate

emigration

immigration

carrying capacity

Population Ecology

Vocabulary

Section 1

Chapter 4

demography

demographic transition

zero population growth (ZPG)

age structure

Population Ecology

Vocabulary

Section 2

Chapter 4


Visualizing Population Characteristi

cs

Characteristics of Population Growt

h

Animation



Documents

Chapter 3 Communities, Biomes, and Ecosystems 3.1 Community Ecology A biological community is a group of interacting populations that occupy the same