APES Unit 3 Key Academic Language

Generalist Species

Species that can thrive in a variety of environmental conditions and can utilize a wide range of resources. They are adaptable and often found in many different habitats. Ex: racoonGeneralist species often have broad diets and can survive in diverse ecosystems, which allows them to cope with changing environmental conditions.

Specialist Species

Species that have specific habitat and resource requirements, meaning they thrive in particular environmental conditions but may be vulnerable to changes. They typically have narrow diets and are specialized for their niche. Specialist species are adapted to specific environments and have limited resource uses, making them less resilient to environmental changes. Ex: Giant Panda

r-selected species

Species characterized by high reproductive rates, small body size, and early maturity. They often produce many offspring with low parental investment, allowing them to thrive in unstable environments. r-selected species tend to have short life cycles and are well-suited for rapid population growth when conditions are favorable, often taking advantage of unpredictable habitats. Ex: Mosquitos

K-Selected Species

Species that mature slowly, produce fewer offspring, provide more parental care, and often live longer.

Ex: Elephants

Reproductive strategies

Patterns of reproduction that species use to maximize their reproductive success in response to environmental conditions. These strategies can be categorized mainly into r-selected and K-selected strategies, reflecting different approaches to offspring production and care. *ways organisms allocate energy ex:number of offspring produced, amount of parental investment

Invasives as r-selected species

Invasive species reproduce early/rapidly; spread quickly, and outcompete with native species; not all invasive species are r-selected.

Population growth and limiting factors in K- vs. r- selected species

r selected populations may increase rapidly and crash when resources run short; K-selected populations generally grow more slowly and often fluctuate near carrying capacity based on resources.

Survivorship Curves

Graphs showing the proportion of a population surviving to different ages.

Type 1 Survivorship Curve

High survival through early and middle life, followed by a steep decline in old age. Ex: Humans

Type 2 Survivorship Curve

A roughly constant chance of death at any age. Ex: Some birds

Type 3 Survivorship Curve

High mortality early in life, with much better survival among those reaching adulthood. Ex: Oysters

K vs. r-selected survivorship curves

K-selected species show Type 1 curves; r-selected species show Type 3 curves. These are tendencies, not rules.

Population

Individuals of the same species living in the same area at the same time

Carrying Capacity (K)

The largest population an environment can sustainably support given its available resources.

Exponential Growth (J- Shaped Curve)

Population increases at an accelerating rate when resources are abundant and limiting factors are minimal.

Logistic Growth (S- Shaped Curve)

Population grows rapidly at first, then slows and levels off near carrying capacity as resources become limited.

Limiting Factors

Resources or conditions that restrict population size or growth, such as food, water, space, or disease.

Density-Dependent Factors

Factors whose effects typically increase as population density rises, such as competition, disease, and predation.

Density-Independent Factors

Factors that affect populations regardless of density, such as floods, droughts, and severe storms.

Case-Study

Kaibab Deer Population: A historical Arizona deer population increased after predator control and hunting restrictions, then declined as forage was depleted. It illustrates overshoot and resource limits, though historical estimates and causes are debated.

Age-Structure Diagrams

Charts showing numbers or porportions of males and females in different age groups; useful for predicting population trends.

Population Pyramid

An age structure diagram with younger age groups at the bottom and older groups at the top.

Stage 2-5 Pyramid Shapes

Stage2: broad base, rapid growth

Stage 3: narrowing base, slowing growth

Stage 4: roughly rectangular, stable growth

Stage 5: narrow base, aging or declining population

Dependent vs. Non-Dependent age cohort impacts on countries

Young people (usually under 15) and older adults (usually over 65) are often considered dependents; the working age group (15-64) generally supports tax revenue and production.

Pre-Reproductive and older age group cohort impacts on countries

Many young people can mean future growth and demand for schools/jobs; many older people increase demand for healthcare, pensions, and elder care.

Societal Problems

Population-related challenges such as crowded housing, limited healthcare, unequal access to resources, and inadequate education.

Economic Problems

Populaton-related financial challenges such as crowded housing, limited healthcare, unequal access to resources, and inadequate education.

HIV/AIDS

HIV attacks the immune system; leads to AIDS without treatment; it can affect mortality, life expectancy, and workforce size. Treatment reduces effects.

TFR (Total Fertility Rate)

The average number of children a woman would have over her lifetime based on current age-specific fertility rates.

Factors that affect TFR: education, access to contraception, healthcare, child mortality, income, cultural norms, and age at marriage or first birth.

Replacement Level Fertility (RLFR)

Fertility needed to replace a generation without migration; approximately 2.1 children because some children die b/f.

Infant Mortality Rate (IMR)

Deaths of infants under age one per 1,000 live births in a year.

Life Expectancy

The average years a newborn is expected to live if current age-specific death rates persist.

Crude Birth Rate (CBR)

Live births per 1000 people in one year.

Crude Death Rate (CDR)

Deaths per 1000 people in one year.

Immigration

Movement of people into a country or population.

Emigration

Movement of people out of a country or population.

NRI (Natural Rate of Increase)

Natural increase excludes migration:

NRI(%): =(CBR-CDR)/10

(when CBR and CDR are per 1,000 people)

Growth Rate

Percent Change in population including migration:

Growth rate (%): [(births-deaths+immigration-emigration)/population]x 100

for a given period of time

Rule of 70

Approximate doubling time (years) =70/annual percentage growth rate

Doubling Time

The time required for a population to double at a constant positive growth rate

At 2% annual growth, about 35 years

Malthusian Theory

Thomas Malthus argued that human population could grow faster than food production, causing shortages and population checks.

GDP (Gross Domestic Product)

The monetary value of final goods and services produced within a country during specified period.

Stages of Demographic Transition

Stage 1: high births/deaths, little growth

Stage 2: death rate falls, rapid growth

Stage 3: birth rates fall, growth slows

Stage 4: low births/deaths, stable or slow growth

Stage 5: births below deaths, potential decline

Less-Developed Countries

Countries with lower average incomes and limited infrastructure or access to education and healthcare; circumstances vary widely.

More Developed Countries

Countries with higher incomes, more developed infrastructure, and access to healthcare/education; often has lower fertility and slower population growth.