Ecology: Properties of Populations

Vocabulary flashcards covering core ecological concepts of population properties, including unitary vs. modular organisms, spatial distributions, density measurement, age structures, dispersal, and biological invasions.

Population

A group of individuals of the same species that inhabit a given area, with the potential for interbreeding and defined spatial boundaries.

Unitary Organism

An organism that begins from a zygote and grows into a genetically unique individual with a determinate form.

Modular Organism

An organism in which the zygote develops into an initial unit of construction that then produces further, similar modules through repeated vegetative growth, common in plants.

Genet (Ortet)

A genetic individual that originates directly from a single fertilized egg or zygote.

Ramet

An asexually produced module derived from a genet that is an exact clone and can function as an independent individual, either physically connected or separate.

Geographic Range

The spatial area that encompasses all the individuals of a species.

Metapopulation

A collection of local subpopulations that are separated spatially by environmental heterogeneity but interconnected by dispersal.

Abundance

The total number of individual organisms present in a population.

Crude Density

The number of individuals of a population per total unit of area.

Ecological Density

The number of individuals of a population per unit of actual living space or suitable habitat.

Random Distribution

A population dispersion pattern where the position of each individual is entirely independent of the positions of other individuals.

Uniform Distribution

A regular population dispersion pattern resulting from negative interactions among individuals, such as resource competition or territorial defense.

Clumped Distribution

The most common spatial dispersion pattern where individuals aggregate together due to patchy resource distribution, social grouping, or vegetative propagation.

Quadrat Sampling

A sampling technique for plants and sessile animals that determines density and abundance by counting individuals within a representative sample of measured sub-areas.

Mark-Recapture Method

A sampling technique for mobile animals where individuals are live-trapped, marked, released, and sampled a second time to calculate population size using $N = \frac{nM}{r}$.

Indices of Abundance

Indirect counts or sign indicators used to estimate population size when direct capture-recapture is impractical, including animal vocalizations, scat, or tracks.

Age Structure

The proportion of individuals in a population divided across distinct age classes: pre-reproductive, reproductive, and post-reproductive.

Primary Sex Ratio

The ratio of males to females at conception, which generally tends to be $1:1$.

Dispersal

The active or passive one-way movement of individuals away from their place of birth or group, maintaining gene flow between subpopulations.

Emigration

The one-way movement of an individual permanently out of a subpopulation.

Immigration

The one-way movement of an individual into a new subpopulation.

Migration

A round-trip movement executed by an animal population that occurs repeatedly over daily or seasonal cycles.

Range Expansion

The geographic enlargement of an organism's distribution resulting from introductions to non-native areas or temporal shifts in environmental conditions.

Biotic Pollution

The introduction of non-native species to novel ecological locations, often facilitated by human activities.

Invasive Species

Non-native organisms that expand rapidly within introduced areas due to the absence of natural predators, competitors, or diseases, often disrupting native communities.