APES CH2 - Princeton Review

Population density

The number of individuals of a population that inhabit a certain unit of area

Population dispersion

How individuals of a population are spaced out in a region

Random dispersion

Positioning is not influenced by other members of the same population

• Plants in fields

Clumped dispersion

Individuals are “flocked together”

• Schools of fish; birds migrating together

Uniform dispersion

Individuals are uniformly spaced throughout their geographic region. The result of competition

• Trees spaced to each receive ample water/light

Biotic potential

The amount that the population grow with unlimited resources

Carrying capacity (k)

The max population size that can be sustainably supported by the resources in the region

J-curve

Exponential (unrestricted) growth with unlimited resources

S-curve

Logistic population growth

• Populations grow exponentially till they approach carrying capacity, then become stable

Rule of 70

70/growth rate to find the doubling time of a population

r-selected organisms

Reproduce early, in large numbers, with little parental care

• Bacteria, algae, protozoa

K-selected organisms

Reproduce late, in small numbers, with major parental care

• Humans, lions, cows

Boom-and-bust cycle

When there are rapid increases and decreases in populations. The population graph is spikey and unstable

• Occurs in r-selected species

Predator-prey cycle

The graph of a prey and its’ predator

• The predator (wolf) follows the prey (bunny)

Density-dependent factors

Population-limiting factors that depend on the density of the population

• Diseases, competition, predation: all increase if there’s a HIGHER population density

Density-independent factors

Population limiting factors that are independent of population density

• Earthquakes, storms, and fires are occur no matter what the population density

Type I

• K-selected

• Live long lives

• Humans

Type II

• Have a 50/50 chance of long life

• Birds

Type III

• r-selected

• Most live a short life but can live long if they make it to a certain point

• Roaches, seeds, fish

Population growth rate

(in - out) / 1,000

Crude birth rate

The number of live births per 1,000 members of the population in a year

Crude death rate

The number of deaths per 1,000 members of the population in a year

Total fertility rate

The number of children a woman will bear during her lifetime

Replacement level

2.1

Replacement birth rate

The number of children a couple must have in order to replace themselves in a population

Reasons for higher RBR

Death of children, non-child bearing females, etc

The reason for the world’s population growth

Decreased death rate (Industrial Revolution)

Majority post-reproductive population

Decreased population size

Majority pre-reproductive population

Increased population size

Population momentum

When a country's fertility rate is 2.1, yet the population size continues to grow b/c the population is majority pre-reproductive

Rapid growth

Triangle

• Kenya, Nigeria, Saudi Arabia

Slow Growth

Slim triangle

• USA, AUS, CAN

Zero Growth

Rectangular

• Denmark, Japan, italy

Negative growth

Smallest at bottom

• Russia, Bulgaria, Germany

Preindustrial state

• Rate of growth: slow

• Birth rate: high

• Death rate: high

• Tough living conditions

Transitional stte

• Birth rate: high

• Death rates: lower

• Rapid population growth

Industrial state

• Rate of growth: high

• Birth rate: lower

• Death rate: similar to BR

• Developing countries

Postindustrial state

• Growth rate: near 0

Reasons for increased population

• Improved nutrition

• Clean water

• Sanitary waste disposal

• Medical care

• Increased food production

Genetically Modified Organisms (GMOs)

Inserting strands of DNA that code for resistance or larger crop size

• May lead to decreased genetic diversity

Malnutrition

Poor nutrition that results from a poorly balanced diet

Undernourishment

Insufficient quanityt/quality of nourishment to sustain proper health/growth

Food deserts

Neighborhoods where the majority of the citizens that reside there are low-income & cannot afford healthy food

Feeding America

A charitable agency that provides food at low/no cost (food banks)

Urban sprawl

The emigration of people out of the city and into the suburbs

Challenges of urban areas

Providing water, dealing with waste, brownfields, transportation, providing green spaces, pollution, congestion etc

Reasons for increased suburbs

People can afford gas to commute, provides space, nicer to live

Reasons for increased city-dwellers

Jobs, closer access to medical care, cultural activities etc

Brownfields

Areas that contain abandoned factories or former residential sites

• Soil/water contamination

Megacities

Cities in less developed countries that have grown very rapidly

• Not good living conditions

Ecological footprint

The amount of Earth’s surface that’s necessary to sustain a particular population

Human impact formula

I = P x A x T

• I= Impact

• P= Population size

• A= Affluence

• T= Technology level

Background extinction rate

The natural rate of extinction

Threatened species

Critically endangered, endangered, vulnerable

Common traits of extinction

• In tropics, mountains, or islands

• Species that need lots of land, have low reproductive rates, have specialized feed habits, and have human value

Biodiversity hot spot

A highly diverse region that faces severe threats and already lost 70% of its original vegetation (are the most endangered)

Ways to reduce extinction

• Live sustainably

• Make animal trade illegal

• Species-by-species approach (breeding captivities)

• Land reserves

Marine Mammal Protection Act (1972)

Protected marine mammals from falling below their optimum sustainable population levels

Endangered Species Act (1973)

Protects and recovers species/habitats that are in danger of extinction throughout all or a significant portion of their range

Lacey Act (1900)

Prohibits the trade of wildlife that have been illegally taken, possessed, transported or sold

Convention on International Trade in Endangered Species (CITES/1973)

Bans the capture, exportation, or sale of endangered/threatened species

Causes of extinction

HIPPCO

• Habitat destruction/fragmentation

• Invasive species

• Pollution

• Population

• Climate change

• Overharvesting/overexploitation