APES 3.1-3.4

Generalist species

Species with a broad ecological niche that can live in various places, eat a variety of foods, and tolerate a wide range of environmental conditions.

Specialist species

Species with a narrow ecological niche that may only thrive in specific habitats and utilize limited food sources.

Population density

The number of individuals in a specific area, calculated as the number of individuals per area unit.

K-selected species (K-strategists)

Species that are typically large, have few offspring, invest significant time and energy in offspring care, mature slowly, and have long lifespans.

r-selected species (r-strategists)

Species that are generally small, produce many offspring, invest minimal care in them, mature quickly, and have short lifespans.

Biotic potential (intrinsic growth rate)

The maximum rate at which a population could increase under ideal conditions, such as unlimited food and space.

Survivorship curve

A graph that illustrates the number of survivors in different age groups for a specific species.

Type I survivorship curve

A curve where most individuals survive infancy and live to old age, eventually dying of old age (e.g., humans).

Type II survivorship curve

A curve where individuals die at a constant rate throughout their lifetime (e.g., birds, rodents).

Type III survivorship curve

A curve where most individuals die young, with few surviving long enough to reproduce (e.g., oysters, plankton, insects).

J-shaped curve (exponential growth)

A growth pattern characterized by unlimited resources and no competition, leading to unrestricted population growth.

S-shaped curve (logistic growth)

A growth pattern where resources are limited, and the population eventually reaches a carrying capacity.

Cohort

A group of individuals of the same age, such as males aged 0-5 years.

Overshoot

When a population exceeds the environment's carrying capacity.

Die-off/dieback

A rapid decline in population size typically following an overshoot of carrying capacity.

Causes of dieback

Factors such as overshoot, famine, drought, and disease that lead to population decline.

Carrying capacity (k)

The maximum number of individuals that an ecosystem can sustainably support due to limited resources.

Population growth rate

The speed at which a specific population grows over a defined period, calculated as births minus deaths divided by total population size.

Density dependent factors

Limiting factors of population growth that are influenced by population size, such as competition for resources.

Density independent factors

Events that limit population growth regardless of population size, such as natural disasters.

Sex ratio

The proportion of males to females in a population, where skewed ratios can hinder population growth.

Population age structure

A description of the distribution of individuals across different age categories in a population, affecting its growth potential.