Unit 3: Populations Study Guide

Comprehensive vocabulary flashcards covering population ecology, reproductive strategies, survivorship curves, age structure diagrams, and demographic transition stages.

Invasive species

A species from an external source brought to a habitat by humans, typically an r-selected generalist that outcompetes native species for resources and drastically affects native populations.

Endangered species

A species that has a very small global population and is in danger of extinction due to human interference, invasive species, or climate change.

African White Rhinoceros

An endangered species that is facing extinction primarily due to poaching for the ivory in their horns.

Generalist species

A species with a large ecological niche that can survive in an extremely wide range of environments and consume a broad variety of resources, such as a raccoon.

Exponential growth

A pattern of population growth associated with r-selected species in which the growth rate accelerates as the population size increases.

Logistic growth

A pattern of population growth associated with K-selected species in which growth slows down as the population nears carrying capacity.

K-selected species

Species characterized by producing fewer offspring, investing higher quality care in their young, and experiencing lower infant mortality rates (IMR).

r-selected species

Species characterized by producing many offspring, providing little to no parental care, and experiencing high infant mortality rates (IMR).

Type I survivorship curve

A survivorship pattern associated with K-selected species characterized by high survival rates at early and middle life stages.

Type II survivorship curve

A survivorship pattern representing species that experience a steadily decreasing rate of survival throughout their entire lifespan.

Type III survivorship curve

A survivorship pattern associated with r-selected species characterized by very low survival rates at young ages.

Carrying capacity

The maximum population size of a species that an environment can sustain, identified on a graph where the population curve levels off or by the average of the fluctuations at the top.

Carrying capacity and overshoot graph

A population graph showing logistic growth leveling off at carrying capacity, including a temporary overshoot followed by population oscillations.

Density-dependent factors

Environmental factors whose influence on population size varies with density, such as availability of food, water, and suitable habitats or homes.

Density-independent factors

Factors that drastically alter population size regardless of its density, such as natural disasters or extreme environmental events.

Age structure categories

The demographic cohorts used to analyze population age diagrams: pre-productive (ages $0$ to $14$), productive (ages $15$ to $45$), and post-productive (ages $45+$).

Age Structure Diagrams

Diagrams illustrating population distributions by sex and age cohorts, categorized into rapid growth, slow growth, stable, and shrinking population profiles.

Total Fertility Rate (TFR)

The average total number of children born to a woman across her lifetime.

Population growth rate formula

The mathematical formula used to calculate growth rate using crude birth rate and crude death rate: $\frac{\text{CBR} - \text{CDR}}{10}$.

Replacement-level fertility

A fertility rate of $2.1$ children per woman in developed countries, set slightly above $2$ to account for individuals who cannot or choose not to have children.

Demographic Transition Model

A five-stage model illustrating the historical shift of human populations from high birth and death rates to low birth and death rates as nations develop.

Stage 2 Demographic Transition

The phase in the demographic transition characterized by high birth rates, rapidly falling death rates, high infant mortality, and rapid population increase.

Stage 4 Demographic Transition

The phase in the demographic transition where birth and death rates both fall to low levels, causing population growth to level off and remain stable.