Population Ecology Lecture Notes

Flashcards covering vocabulary and key concepts of Population Ecology, including sampling methods, growth models, and survivorship patterns.

Population

All the organisms that belong to the same species that are living within a designated area and can interact, breed and have offspring.

Population Density

The number of individuals per unit area or volume ($n/\text{unit area}$).

Mark-recapture method

A sampling technique where individuals are trapped, captured, marked with a tag, recorded, and then released; after time, traps are set again to capture and identify individuals to estimate wildlife populations.

Active Sampling

A method where the researcher actively looks for organisms, such as netting or using quadrats.

Quadrat

A square that encases an area within a habitat, Typically used for sampling populations of plant species or slow-moving animal species.

Transect Sampling

A method of collecting data by moving along a straight line through an area and recording observations.

Passive Sampling

A method where traps, such as mist nets or pitfall traps, are set to catch organisms without the researcher actively searching.

Pitfall traps

A container buried in the ground to catch small animals such as insects, spiders, amphibians, and reptiles.

Immigration

The influx of new individuals to a population from other areas.

Emigration

The movement of individuals out of a population.

Dispersion

The pattern of spacing among individuals within the geographic boundaries of a population.

Random dispersion

A pattern where the position of each individual is independent of others and spacing is unpredictable, occurring in the absence of strong attraction or repulsion.

Clumped dispersion

A pattern where individuals aggregate in patches, often where soil conditions favor growth or to facilitate mating and group defense.

Uniform dispersion

A pattern where individuals are evenly spaced, often resulting from territoriality or chemical inhibition of neighbors.

Biotic potential

The unrestricted growth of a population as each member survives and produces offspring, resulting in maximum growth.

Resistance factors

Also called limiting factors, these are things that directly or indirectly reduce a population's size and keep biotic potential in check.

Density-dependent limiting factors

Factors that alter a population's growth depending on the population's density, usually biotic, such as competition, predation, and disease.

Interspecific competition

Competition that occurs between members of different species.

Intraspecific competition

Competition between organisms of the same species.

Density-independent limiting factors

Factors that affect population growth rate regardless of density, typically abiotic, such as natural disasters, storms, and fires.

Exponential growth

A population growth model represented by a J-shaped curve, occurring when a population has unlimited resources and growth rate increases over time.

Logistic growth

A population growth model represented by an S-shaped curve, occurring when resources are limited and growth rate decreases as the population approaches carrying capacity.

Carrying Capacity ($K$)

The maximum population size that a particular environment can support indefinitely.

Stable Equilibrium

A state met when the population aligns with the carrying capacity line.

Minimum Viable Population (MVP)

The smallest population size at which a species can exist without facing extinction due to inbreeding, disasters, or limiting factors.

Cyclical oscillations

Regular cycles of boom (increase) and bust (decrease) in population size, typically occurring due to species interactions or density-dependent factors.

Demography

The study of the vital statistics of populations, such as birth and death rates, and how they change over time.

Life table

A table providing data regarding the life history of an organism, including mortality rates, life expectancies, and percentage of organisms in specific age intervals.

Type I Survivorship Curve

A curve that is flat at the start (low early death rate) and drops steeply in older age groups; exhibited by humans and large mammals.

Type II Survivorship Curve

A curve representing a constant mortality rate over the organism's entire life span; seen in some rodents and annual plants.

Type III Survivorship Curve

A curve that drops sharply at the start (high early death rate) and flattens out for survivors; associated with organisms that produce many offspring with little parental care.

$K$-selected species

Species adapted to stable environments that mature later, live longer, produce fewer/larger offspring, and provide high-level parental care (e.g., elephants, humans).

$r$-selected species

Species adapted to changing environments that mature quickly, have short life spans, produce many offspring, and provide little parental care (e.g., mice, insects).

Top-down regulation

The control of a population's size due to pressures from the top trophic level, such as predation, disease, and natural disasters.

Bottom-up regulation

The control of a population's size due to factors at the bottom of a trophic pyramid, such as nutrients, water, sunlight, and habitat.