BIOL 1010 | Chapter 36 Definitions

population

A group of individuals of a single species that occupy the same general area, share resources, interact, and are likely to breed with one another.

population ecology

The study of changes in population size and the factors that regulate populations over time, including how individuals are distributed and how populations interact with their environment.

population dynamics

The study of interactions between biotic and abiotic factors that cause variation in population size over time, including births, deaths, immigration, and emigration.

population density

The number of individuals of a species per unit area or volume, such as trees per square kilometer or earthworms per cubic meter.

dispersion patterns

The spatial arrangement of individuals within a population’s area, showing how organisms are distributed relative to one another.

clumped dispersion pattern

A pattern in which individuals are grouped in patches, usually due to uneven distribution of resources, social behavior, or reduced predation risk.

uniform dispersion pattern

A pattern in which individuals are evenly spaced, often resulting from territorial behavior or competition for resources.

random dispersion pattern

A pattern in which individuals are spaced unpredictably, with no clear pattern, typically due to neutral interactions or chance events, and is relatively rare.

life tables

Tables that track the survivorship of individuals in a population at different ages, showing the probability of surviving from one age interval to the next. They help identify the most vulnerable life stages of a species.

survivorship curves

Graphs that plot the proportion of individuals surviving at each age from an initial population, illustrating patterns of mortality and life history strategies.

exponential growth

A pattern of population increase under ideal conditions where the growth rate is constant and unlimited, causing the population to rise rapidly in proportion to its current size, producing a J-shaped curve.

per capita rate of increase (r)

The average contribution of each individual to population growth per time interval, calculated as the difference between birth rate and death rate per individual.

limiting factors

Environmental constraints, both biotic and abiotic, that restrict population growth as a population approaches the maximum sustainable size.

logistic growth model

A population growth model that incorporates limiting factors, showing growth that slows as the population nears carrying capacity, producing an S-shaped curve.

carrying capacity (k)

The maximum population size that a particular environment can sustainably support, given available resources, space, and other environmental conditions.

density-dependent factors

Limiting factors whose intensity increases as population density increases, affecting birth rates, death rates, or both.

intraspecific competition

Competition between individuals of the same species for limited resources, such as food, space, or mates.

density-independent factor

A limiting factor whose impact on a population is unrelated to population density, typically abiotic, like weather or natural disasters.

booms

Periods of rapid exponential population growth, during which the number of individuals in a population increases dramatically.

busts

Periods during which a population declines sharply, often returning to minimal levels after a boom.

predation hypothesis

The idea that predators are the primary cause of population declines in prey species, controlling prey population cycles.

life history

The schedule of an organism’s reproduction and survival, including traits such as age at first reproduction, frequency of reproduction, number of offspring, and amount of parental care.

r-selection

A life history strategy in which organisms maximize reproductive rate (r) by producing many offspring, developing rapidly, and providing little or no parental care; advantageous in unstable or unpredictable environments.

K-selection

A life history strategy in which organisms maximize survival near carrying capacity (K) by producing few, well-cared-for offspring, growing slowly, and investing heavily in parental care; advantageous in stable, competitive environments.

sustainable resource management

The practice of using natural resources without depleting them, ensuring that populations of harvested or conserved species can replenish and persist over time.

sustainable harvest levels

The amount of a population that can be removed through harvesting without reducing its ability to regenerate and maintain long-term viability.

integrated pest management (IPM)

A strategy that combines biological, chemical, and cultivation methods to control pest populations while minimizing ecological damage, based on an understanding of pest and predator population dynamics.

demographic transition

A shift in a population from high birth and death rates to low birth and death rates, resulting in a change from slow to more stable population growth.

age structure

The distribution of individuals among different age groups in a population, often visualized with age-structure diagrams to predict future growth.

fertility rate

The average number of children a woman produces over her lifetime, which influences population growth.

population momentum

The continued population growth after fertility rates have declined to replacement level, caused by a large proportion of young individuals entering reproductive age.

ecological footprint

An estimate of the land and water area required to supply the resources a person or population consumes (food, fuel, housing) and to absorb the waste they generate.

carbon footprint

The portion of an ecological footprint that measures the amount of carbon dioxide and other greenhouse gases emitted by an individual, population, or activity.

biocapacity

The ability of Earth’s ecosystems to regenerate resources (such as crops, forests, and fisheries) and absorb waste, expressed as the productive land and water area available.

sustainability

The practice of using natural resources in ways that meet current human needs without compromising the ability of future generations to meet theirs.