Unit 3: Population Ecology

A set of vocabulary flashcards covering key concepts in Population Ecology.

Population growth rate (Intrinsic growth rate)

The maximum potential rate of increase for a group of organisms under ideal conditions with unlimited resources.

Biotic potential

The maximum reproductive rate of an organism or group of organisms is limited only by the number of offspring produced, the sex ratio, and the age at which reproduction begins.

K-selected species

Organisms that reproduce late in life, have few offspring, and devote significant time and energy to nurturing each offspring.

Carrying capacity

The maximum size of a group of organisms that a particular habitat can sustain indefinitely without degradation of the environment.

r-selected species

Organisms that reproduce early, have many offspring, and often provide little to no parental care.

Overshoot

When a group of organisms' numbers temporarily exceed the maximum size the environment can support.

Dieback (Die-off)

A sharp reduction in the number of organisms in a population, often resulting from an environment's inability to support the previous number.

Survivorship curve

A graph showing the number or percentage of individuals surviving at each age for a given group of organisms.

Type I survivorship curve

A pattern where most organisms survive to old age, and mortality rates are highest among the elderly.

Type II survivorship curve

A pattern where individuals have a relatively constant rate of mortality throughout their lifespan.

Type III survivorship curve

A pattern where most organisms die early in life, and mortality rates are lowest for those few that survive to maturity.

Density-dependent factor

A condition that influences the size of a group of organisms more strongly as the number of individuals per unit area increases.

Density-independent factor

A condition that affects the size of a group of organisms regardless of how many individuals are in a given area.

Population growth models

Mathematical formulations used to describe how the number of individuals in a group changes over time.

Fecundity

The actual ability or capacity of an organism to produce offspring over its lifetime.

Exponential growth model

A pattern of increase where a group's size increases at a constant proportion of its current size.

J-shaped curve

The characteristic visual representation of unrestricted increase in a group of organisms.

Logistic growth model

A pattern of increase where a group's size initially grows quickly but then slows down as the number approaches the maximum sustainable size.

S-shaped curve

The characteristic visual representation of an increase that starts fast and then levels off at the environment's maximum sustainable size.

Limiting resource

A factor that is most scarce relative to a group's needs, thus restricting the maximum sustainable size.

Population Density

The number of individuals of the same species that reside within a specific unit of area or volume.

Population Distribution

The spatial arrangement of individuals in a given habitat.

Uniform Distribution

A pattern where individuals are spaced more or less evenly throughout an area.

Random Distribution

A pattern where individuals are located unpredictably and without any discernible pattern.

Clumped Distribution

A pattern where individuals aggregate in patches, the most common arrangement in nature.

Predation

An interaction where one organism captures, kills, and consumes another organism.

Competition

The struggle among organisms for the same limited resources.

Intraspecific Competition

The struggle for resources that occurs among individuals of the same species.

Interspecific Competition

The struggle for resources that occurs between individuals of different species.

Specialist Species

Organisms that thrive only in a narrow range of environmental conditions or have a very limited diet.

Generalist Species

Organisms that can thrive in a wide variety of environmental conditions and utilize a diverse range of resources.