UNIT 4 ECOLOGYChapters 8, 9, 10

CHARACTERISTICS OF COMMUNITY

Physical appearance- Species diversity- Niche structure-

SPECIES-RICH ENVIRONMENTS

Tropical rain forests

Coral reefs Deep sea Large tropical

lakes

Latitude- terrestrial communities- highest at lower latitudes

Pollution in aquatic ecosystems- species decrease with pollution

DIVERSITY IN ISOLATED ECOSYSTEM

Determined by: Immigration Extinction

THEORY OF ISLAND BIOGEOGRAPHY

Balance between immigration rate & extinction rate

Size of island- Distance from mainland-

SPECIES

Native- Nonnative- Indicator- Keystone-

INDICATOR SPECIES

Birds- Amphibians-

DECLINE IN INDICATOR POPULATION

Habitat loss & fragmentation Prolonged drought Pollution Increases in UV Increased incidences of parasitism Overhunting Nonnative predators/competitors &

diseases organisms

KEYSTONE ECOLOGICAL ROLES

Flying foxes- Alligators- Sharks-

Loss of keystone species = population crashed, extinctions of other species

FOUNDATION SPECIES

Species that shape communities by creating or enhancing habitats that benefit other species

African elephants-

INTERSPECIFIC COMPETITION

Between species for shared or scarce resources

Consequences:

RESOURCE PARTITIONING

Scarce resources used at different times, in different ways, or in different places

Adaptations lead to specialization

PREDATION

Benefits to prey Unfit Competition Population control

Pursuit & ambush

Avoidance Parasitism Mutualism Commensalism

SUCCESSION

Primary- lifeless ground Pioneer species-

Secondary- soil or sediment remains Midsuccessional plants- Late successional plants- can tolerate

shade Facilitation- Inhibition- Tolerance-

INTERMEDIATE DISTURBANCE HYPOTHESIS

Communities that experience fairly frequent but moderate disturbances have highest biodiversity

DEALING WITH DISTURBANCES

Inertia- Constancy- Resilience-

PRECAUTIONARY PRINCIPLE

When there is evidence that a human activity can harm our health or bring about changes in environmental conditions that can affect our economies or quality of life, we should take measures to prevent harm even if some of the cause-and-effect relationships have not been fully established scientfically

POPULATION DYNAMICS

Study how populations change in size, density, age distribution as a response to changes in environmental conditions

Population clumps indicate-

POPULATION CHANGE

Population change = [births + immigration] – [death + emigration]

BIOTIC POTENTIAL

Capacity for growth

High intrinsic rate of increase (r): -

ENVIRONMENTAL RESISTANCE

Factors that limit population growth

Carrying capacity (k)-

Consequences of exceeding k-

DENSITY-DEPENDENT FACTORS

Greater effect as population density increases

Examples-

DENSITY-INDEPENDENT FACTOTS

Same effect regardless of density

Examples-

POPULATION TRENDS

Stable- Irruptive- Irregular- Cyclic-

POPULATION CONTROL

Top-down-

Bottom-up-

REPRODUCTION

Asexual- Sexual-

SEXUAL REPRODUCTION

-Males do not give birth-Increased chance of errors & defects+Greater genetic diversity-Energy consumed in courtship/mating+Males help protect & train

OPPORTUNIST SPECIES

R-selected Rate Age Energy Offspring Parental care Population size

COMPETITOR SPECIES

K selected Age Offspring Development Size Parental care

DIVERSITY IN SMALL, ISOLATED POP.

Founder effect- Demographic bottle neck- Genetic drift-

METAPOPULATION

Collections of interacting local populations of a species

HUMAN MODIFICATIONS OF ECOSYSTEMS Habitats Simplifying/homogenizing natural

ecosystems NPP Pests & bacteria Elimination, introduction,

overharvesting Chemical cycling, energy flow Fossil fuels

REDUCING THAILAND’S BIRTH RATE

Government supported family planning program

High female literacy rate Increased economic role for women Advances in women’s rights Better healthcare for women & children

DEMOGRAPHY

Study of size, composition, & distribution of human populations & cause/consequences of changes in characteristics

HUMAN POPULATION SIZE

Affected by: Births Deaths Immigration Emigration Crude birth rate- live births/1000 Crude death rate- deaths/1000

ANNUAL RATE OF POPULATION CHANGE Annual rate = (birth-death) / 10

WORLD’S LARGEST POPULATIONS

1. China2. India3. United States

DOUBLING TIME

Time in years for population growing at specified rate to double its size

Rule of 70 = 70 / % growth rate = doubling time (in years)

FERTILITY

# of births that occur to an individual woman

Replacement-level fertility-

FACTORS AFFECTING BIRTH/FERTILITY RATES

Children Pensions Urbanization Women’s status; marriage age; birth

control Infant mortality rate; legal abortions Religious beliefs, traditions, cultural

norms

DECLINE OF DEATH RATE

Increased food supplies Better nutrition Advances in medicine Improved sanitation Safer water supplies

LIFE EXPECTANCY

Average # of years newborn can expect to live

Infant mortality rate-

High IMR- indicates:

U.S. IMR

Inadequate health care for poor women & their babies

Drug addiction High teenage birthrate

U.S. IMMIGRATION

41% population growth from immigration

Reducing immigration: Allow population to stabilize Reduce environmental impactOpposition Diminish role of U.S. as place of

opportunity Immigrants needed as workers

AGE STRUCTURE

Distribution of males/females in each age group

Growth predicted- large bottom =

UNDER 15

World – 30% Developed countries – 17% Developing countries – 33%

Market products/services- directed to upcoming bulge in age structure diagram

RAPID POPULATION DECLINE

-Baby bust-More elders consuming larger share of

medical care, social security fund-Decreasing working taxpayers-Increased retirement age-Cut retirement benefits-Higher taxes

-Increased legal immigration-Loss of working/trained professionals+Increased financial assistance for

education & health care+Volunteers- teachers, health-care,

social workers

AIDS- drop in life expectancy = premature deaths

DEMOGRAPHIC TRANSITION

Hypothesis that countries as they become industrialized have declines in death rates followed by declines in birth rates

Preindustrial phase- Transitional stage- Industrial stage- Postindustrial stage-

PREVENTION

Lack of skilled workers Lack of financial capital Lack of resources Rise in debt to developed countries Too little money left for improving

social, health, & environmental conditions

FAMILY PLANNING

Provides educational & clinical services that help couples choose how many children to have & when to have them

Advantages-

EMPOWERING WOMEN

Bottom-up change giving women full legal rights & opportunity to become educated & earn income outside the home

MAJOR POPULATION PLANS

Universal access to family planning services & reproductive health care

Improve health care National population policies Improve women’s status Provide more education for females Increase involvement of men in child-

rearing

Reduce poverty Reduce unsustainable production &

consumption