Unit 3: Populations in AP Environmental Science

Generalist species

Occupy broad niches, can live many places, eat many types of food, tolerate a wide range of environmental conditions (flies, cockroaches, mice, etc.)

Specialist species

Have narrow niches, live in only one type of habitat, eat only one or a few types of food, tolerate only a narrow range of climactic and environmental conditions (tiger salamander, red

K

Selected Species

r

Selected Species

Intrinsic rate of increase (r)

The rate at which a population would grow on unlimited resources.

Biotic potential

All the factors which cause a population to increase in growth.

Survivorship curves

Show the number of survivors of each age group for a particular species, indicating life expectancy and probability of death for individuals at each age.

Traits of K

selected species

Examples of K

selected species

Traits of r

selected species

Examples of r

selected species

Carrying capacity (K)

The maximum population size that an environment can sustain indefinitely.

Population growth

The increase in the number of individuals in a population.

Resource availability

The availability of resources that can support a population's growth.

Age structure diagrams

Visual representations of the distribution of various age groups in a population.

Total fertility rate

The average number of children that would be born to a woman over her lifetime.

Human population dynamics

The study of how and why human populations change over time.

Demographic transition

The transition from high birth and death rates to lower birth and death rates as a country develops.

Type I survivorship curves

high survival rates throughout most of the species' life spans with large numbers of die

Type II survivorship curves

relatively constant decline in survivorship throughout the species' life spans

Type III survivorship curves

low survivorship early in life with few individuals reaching adulthood (r

EARLY LOSS

typical for r

Examples of early loss

Annual plants & bony fish

MANY DIE VERY EARLY IN LIFE

refers to r

LATE LOSS

K

CONSTANT LOSS

intermediate reproductive patterns seen in squirrels, song birds, etc.

Carrying Capacity

the number of individuals of a species the environment can sustain indefinitely

Environmental Resistance

all the factors that limit the growth of a population

K

carrying capacity, determined by environmental resistance + biotic potential

Population Overshoot

occurs when populations exceed K due to a reproductive time lag

Dieback or Crash

occurs unless organisms can move or switch to new resources when populations exceed K

Population Oscillation

real populations tend to oscillate around carrying capacity (K)

Exponential Growth Model

mathematical equations that predict population size at any moment in time

Intrinsic growth rate (r)

maximum potential for growth of a population under ideal conditions, with unlimited resources available

Exponential growth formula

Nt = N0ert

Nt

estimate of future population size

N0

individuals currently in the population

Logistic Growth Model

describes a population whose growth is initially exponential but slows as it approaches the carrying capacity

S

shaped curve

Density

dependent constraints

Fluctuating carrying capacities

can occur seasonally or from year to year

Reproductive time lag

the period needed for birth rates to fall and death rates to rise

Reproductive time lag

Can produce a die

Carrying capacity

The limit to how many individuals an environment will sustain, due to a limiting resource.

Population crash

A significant decline in the number of individuals in a population.

Population fluctuations

Four general types of population fluctuations in nature are: stable, irruptive, cyclic, and irregular.

Stable population

Fluctuates slightly above and below carrying capacity and is characteristic of many species living under fairly constant environmental conditions.

Irruptive population

Some species have a fairly stable population size that may occasionally irrupt to a high peak and then crash to below carrying capacity.

Cyclic fluctuations

Occur over a regular time period, generally a multiple

Density

dependent factors

Limiting resource

A resource that a population cannot live without and which occurs in quantities lower than the population would require to increase in size.

Environmental resistance

All factors that limit the growth of a population, and largely determine an area's carrying capacity.

Density

independent factors

Age structure diagrams

Visual aids that show the distribution of males and females in each age group.

Pre

reproductive ages

Reproductive ages

Include age 15 through 44.

Post

reproductive ages

Population pyramid

A diagram that is wider at the bottom, indicating more young people than old people, typical of developing countries.

Population momentum

The phenomenon where populations keep growing after birth control policies or voluntary birth reductions have begun to lower CBR of a country.

Column age structure

Countries with little difference between the numbers of individuals in different age groups, typical of developed countries with a slow or no growth rate.

Inverted pyramid

A diagram that resembles a country with more older than younger people, indicating a fertility rate below 2.1.

Total fertility rate (TFR)

An estimate of the average number of children that each woman in a population will bear throughout her reproductive years.

Population growth

Occurs when a country has a wide base in its age structure diagram, indicating a large number of females yet to have children.

Examples of population crashes

Include the Irish potato famine, the bubonic plague, and the current AIDS epidemic.

Density

dependent population control

Replacement

level fertility

Developed countries

Countries with relatively high levels of industrialization and income.

Developing countries

Countries with relatively low levels of industrialization and incomes of less than $3/person/day.

Birth and fertility rates

Rates influenced by factors such as economic costs, access to family planning, and women's education.

Life expectancy

The average number of years that an infant born in a particular year in a particular country can be expected to live.

Infant mortality rate

The number of babies out of every 1,000 born who die before their first birthday.

Child mortality rate

The number of deaths of children under age 5 per 1,000 live births.

Demography

The study of human populations and population trends.

Demographers

Scientists who study human populations and trends.

Population changes

Population increases through births and immigration and decreases through deaths and emigration.

Immigration

The movement of people into a country.

Emigration

The movement of people out of a country.

Crude birth rate (CBR)

The number of live births per 1,000 individuals per year.

Crude death rate (CDR)

The number of deaths per 1,000 individuals per year.

Global population growth rate

Calculated as [CBR

Growth rate for a nation

Calculated as [(CBR + immigration)

Doubling time

The number of years it takes for a population to double, assuming the growth rate is constant.

Rule of 70

Doubling time (in years) = 70/growth rate.

Infectious diseases

The second biggest killer worldwide after heart disease.

HIV/AIDS

Responsible for the most deaths from infectious diseases annually.

Prenatal care

An important predictor of infant mortality.

Factors influencing fertility

Include economic costs, access to family planning, women's education, and legal access to abortions.

AIDS

A disease that disrupts a country's social and economic structure by removing large numbers of young adults from the population.

Life expectancy

The average period that a person may expect to live, which drops due to diseases like AIDS.

Child & infant mortality

The death rates of children and infants, which increase as a result of diseases like AIDS.

Population growth

The increase in the number of individuals in a population, which declines due to diseases like AIDS.

Family Planning

The regulation of the number or spacing of offspring through the use of birth control.

Total Fertility Rate (TFR)

A measure that has dropped by at least 55% in developing countries due to family planning.

Unplanned pregnancies

Pregnancies that occur without prior planning, which account for 42% in developing countries.

Affluence

The state of having high levels of money, goods, or property, resulting in high levels of consumption.

Ecological footprint

A measure of human demand on the Earth's ecosystems, with the wealthiest countries averaging 15.8 acres per capita.

Extreme poverty

A condition where 1/5 of the world population is unable to fulfill their basic needs.

Malnutrition

A significant health issue characterized by a lack of proper nutrition.

Inadequate sanitation

A significant health issue related to insufficient access to clean facilities and safe drinking water.

Respiratory disease

A significant health issue affecting the poor, often exacerbated by environmental conditions.