Advanced Study Notes: Population Dynamics (APES Unit 3)

Range of Tolerance

The optimal range of abiotic conditions (e.g., temperature, humidity) that allows a species to thrive.

Generalist Species

Species with a broad ecological niche; can utilize a variety of resources and adapt to changing environments.

Specialist Species

Species with a narrow ecological niche; has specific resource requirements and thrives in stable environments.

K-Selected Species

Species that invest heavily in a few offspring to ensure their survival, focusing on quality over quantity.

r-Selected Species

Species that produce many offspring in a short time, focusing on quantity over quality.

Survivorship Curve

A graph that displays the relative survival rates of a cohort from birth to maximum age.

Type I Survivorship Curve

High survival in early and middle life stages, with a rapid decline in later life stages.

Type II Survivorship Curve

Survival probabilities are roughly equal at all ages, with a constant mortality rate.

Type III Survivorship Curve

Very high mortality in early life stages, with few survivors living long lives.

Carrying Capacity (K)

The maximum number of individuals of a population that a specific environment can sustain indefinitely.

Overshoot

When a population exceeds its carrying capacity, typically due to a delay in reproductive response.

Dieback

A rapid decrease in population size following an overshoot due to resource depletion.

Population Growth

The increase in the number of individuals in a population over time.

Exponential Growth

Growth of a population under ideal conditions with unlimited resources, depicted by a J-curve.

Logistic Growth

Population growth that slows as it approaches carrying capacity, illustrated by an S-curve.

Limiting Factor

The scarcest resource that limits population growth according to Liebig's Law of the Minimum.

Density-Dependent Factors

Factors whose effects increase as population density rises, often biological in nature.

Density-Independent Factors

Factors that impact the population regardless of its size, typically abiotic events.

Age Structure Diagram

A histogram that shows the distribution of various age groups in a population.

Prereproductive Cohort

Individuals aged 0–14, indicating future population growth potential.

Reproductive Cohort

Individuals aged 15–44, indicating current birth rates.

Postreproductive Cohort

Individuals aged 45 and older, representing the aging population.

Total Fertility Rate (TFR)

The average number of children a woman will have in her lifetime.

Replacement Level Fertility

The TFR required to maintain a stable population size.

Population Momentum

The continued growth of a population after fertility rates have dropped due to a large base of young individuals.

Rule of 70

A mathematical formula used to estimate the doubling time for a population growing exponentially.

Thomas Malthus

Economist who predicted that population grows geometrically while food supply grows arithmetically.

Demographic Transition Model (DTM)

A model that explains transitions from high birth/death rates to low birth/death rates in industrializing countries.

Stage 1: Pre-Industrial

Characterized by high birth and death rates, resulting in slow and stable population growth.

Stage 2: Transitional

High birth rates with rapidly declining death rates, leading to rapid population growth.

Stage 3: Industrial

Declining birth rates and low death rates causing slowing population growth.

Stage 4: Post-Industrial

Low birth and death rates resulting in stabilizing population growth.

Stage 5: Declining (Theoretical)

Birth rates drop below replacement level, leading to negative population growth.

Anthropogenic Habitat Destruction

Human-caused alterations to habitats that can affect species survival.

Environmental Resistance

Factors that slow population growth as it approaches carrying capacity.

Boom-and-Bust Cycles

Population fluctuations characterized by rapid growth followed by sharp decreases.

K-Selected species examples

Humans, Elephants, Whales.

r-Selected species examples

Mosquitoes, Bacteria, Dandelions.

Abiotic factors

Non-living chemical and physical parts of the environment that affect living organisms.

Biotic factors

Living components of an ecosystem that affect other organisms.

Natural Disasters

Severe storms or geological events that impact populations and environments.

Health and Sanitation Improvements

Advancements that lead to decreased mortality rates in populations.

Cultural Lag

Delay in societal adaptation to changes, affecting birth rates.

Government Policies on Fertility

Strategies influencing reproductive rates, such as pro-natalist or anti-natalist policies.

Population Density

The number of individuals per unit area in a population.

Crude Birth Rate (CBR)

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

Crude Death Rate (CDR)

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