AP®︎ Environmental Science: Unit 3 Flashcards

A species with a broad niche that can use varied resources, tolerate many conditions, or occupy multiple habitats; it tends to be advantaged in changing habitats

A species with a narrow niche that depends on restricted resources, conditions, habitats, or relationships; it tends to be advantaged in stable habitats

Species that tend to be large, mature late, live long, produce few offspring, invest substantial energy and parental care in each, and reproduce repeatedly in stable, highly competitive environments; their low biotic potential makes recovery slow and increases vulnerability to invasive species

Species that typically mature early, produce many offspring with little parental investment, have short life spans, and increase rapidly in disturbed or unpredictable, low-competition environments; most invasive species display these traits

The spectrum of reproductive strategies between r- and K-selected endpoints; species may combine traits, occupy intermediate positions, or change strategies with conditions

The maximum reproductive rate of a population under ideal conditions

A graph showing the proportion of an original same-age cohort still alive at each age, from birth to the maximum age reached

A group of individuals of the same age, usually born or hatched during the same period, that is followed through its life span

High survival through early and middle life followed by steep late-life mortality; typical of K-selected species with few offspring and high parental investment

A roughly age-independent risk of death, shown as an approximately straight decline on a logarithmic survivorship axis; it can occur in K-selected species

Very high early-life mortality followed by greater survival among the few remaining individuals; typical of r-selected species with many offspring and little parental care

The largest population of a species that an environment can sustain over the long term under given conditions; represented by K.

The condition in which population size exceeds carrying capacity (N > K), often causing resource depletion and environmental damage

The consumption or loss of a resource faster than it can be replenished, reducing the resource base available to support a population

A rapid, substantial population decline that may follow overshoot as resource scarcity causes famine, disease, conflict, or reduced reproduction

An environmental condition or scarce resource that restricts population growth; another abundant resource cannot compensate for it

The combined effect of limiting factors that prevent a population from reaching its unrestricted growth potential

Growth by approximately the same proportion per interval, producing increasing absolute additions and a J-shaped curve; Nₜ = N₀(1 + r)ᵗ.

S-shaped growth that slows as limiting factors intensify and the population approaches carrying capacity

An individual’s or population’s reproductive output or capacity to produce offspring

A shrinking resource base lowers resource availability and carrying capacity, intensifies competition, reduces fecundity, and increases mortality, so a population may overshoot the new carrying capacity and undergo delayed decline or dieback

Graph showing a population’s distribution by age and sex at a particular time, with age on the vertical axis and population number or percentage on the horizontal axis

The approximate 0–14, 15–44, and age-45-and-older groups representing people who have not yet entered, are currently within, or have passed the course’s demographic reproductive-age category

Broad-based, pyramid-like shape with younger cohorts larger than older cohorts, indicating likely rapid growth as many young people enter reproductive age

Column-like, bell-shaped, or nearly rectangular structure; similar-width younger and middle cohorts indicate relative stability, while a slightly wider base indicates slow growth

Narrow-based, urn-shaped, or top-heavy structure with younger cohorts smaller than middle cohorts, indicating likely long-term decline

The tendency of a population to keep growing or declining because of its existing age distribution even after fertility changes

The average number of children a woman is expected to have over her reproductive lifetime, measured in children per woman

The TFR needed to replace the parental generation, approximately 2.1 children per woman; it tends toward long-term stability without net migration or major mortality changes

TFR generally falls with access to family planning, contraception, education, and economic opportunities for women or with antinatalist policies, while pronatalist policies and incentives can raise it

Deaths of infants under age one per 1,000 live births in a year; it generally falls with improved maternal healthcare and nutrition

Infant mortality generally falls with improved maternal and infant healthcare, nutrition, sanitation, clean water, education, and economic conditions and rises when these are inadequate

Population change is ΔN = (B + I) − (D + E): births and immigration add people, while deaths and emigration remove them

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

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

Immigration is movement into a population and increases its size, whereas emigration is movement out of a population and decreases its size

The annual rate of population change from births and deaths alone; RNI (%) = (CBR − CDR) ÷ 10 when rates are per 1,000

The estimated years for a population to double: 70 ÷ annual percentage growth rate, assuming a positive, approximately constant rate

A factor whose effect strengthens as population density rises, such as competition, food or water scarcity, disease transmission, or limited space

A factor whose occurrence or basic effect is not caused by population density, such as a major storm, wildfire, heat wave, or drought

Malthus's theory that population can grow exponentially faster than food supply, so finite resources eventually limit unchecked growth

Family planning and preventive checks reduce birth rates, while food scarcity, crowding, disease, conflict, disasters, and other density-dependent or density-independent factors can raise death rates

Four-stage model relating development to birth rates, death rates, and population growth; death rates typically fall before birth rates

High, often variable CBR and CDR produce little natural growth and a relatively small population

CDR falls while CBR remains high, creating a wide gap between the rates and rapid population growth

CBR declines while CDR remains low, so population continues growing but at a slowing rate

Low CBR and low CDR produce low, near-zero, or sometimes slightly negative natural population growth

Developing countries generally have higher infant mortality, more children in the workforce, and higher birth rates; developed countries generally have lower levels of each