CHAPTER 53 Population Ecology — The Logistic Growth Model (Vocabulary)

Vocabulary flashcards covering the logistic growth model, carrying capacity, and related ecological concepts from the lecture notes.

Carrying capacity (K)

The maximum population size that an environment can sustain indefinitely; varies with resource abundance and other limiting factors, and can differ across space and time.

Logistic growth model

A population growth model in which per capita growth rate decreases as N increases, producing a sigmoid (S-shaped) growth curve; described by dN/dt = rN(K−N)/K (or rN(1−N/K)).

Exponential growth model

A growth model in which resources are unlimited and the per capita growth rate is constant, leading to constant proportional growth (dN/dt = rN).

Per capita growth rate

Growth rate per individual; in the logistic model it declines as population size N increases due to limited resources.

Intrinsic rate of increase (r)

The maximum per capita rate of increase under ideal conditions; a constant used in the exponential and logistic growth equations.

dN/dt

The rate of change in population size over time; the growth rate of the population.

(K−N)/K

The fraction of carrying capacity still available for population growth; near 1 when N is small and near 0 when N is close to K.

Sigmoid (S-shaped) growth curve

A population growth pattern that is slow at first, accelerates at intermediate sizes, and slows again as N approaches K.

Density-dependent factors

Factors whose impact increases with population density (e.g., disease, competition for resources) and can reduce births or increase deaths as N rises.

Overshoot

A temporary exceedance of carrying capacity due to delays in negative feedback before the population settles back toward K.

Time lag in logistic feedback

A delay between changes in population size and the realized effect on growth, which can cause overshoot or fluctuations.

Carrying capacity variation

Variation of K across space and time based on the availability of limiting resources such as energy, shelter, water, and nutrients.

Conservation biology application of the logistic model

Using logistic growth concepts to predict recovery, estimate sustainable harvest rates, and determine minimum viable population sizes to avoid extinction.

Minimum viable population / Critical size

The smallest population size necessary to persist over time and avoid extinction; related to sustainable management of species.