Ecology: Interspecific Competition and the Lotka-Volterra Model

Vocabulary flashcards covering the concepts of interspecific competition, niche differentiation, the Lotka-Volterra competition model, and related experimental ecological studies.

Competitive Exclusion Principle

The ecological concept stating that two species using a limiting resource in the same way (or occupying the exact same niche) cannot coexist indefinitely.

Resource Partitioning

The differential use of limiting resources in space, food, or habitat by coexisting species to reduce interspecific competition.

Character Displacement

An evolutionary divergence in anatomical or behavioral characteristics (such as beak size or toe length) driven by natural selection to minimize competition between coexisting species.

Alpha ($\alpha$)

A competition coefficient in the Lotka-Volterra model that converts individuals of species 2 into equivalent competitive units of species 1.

Beta ($\beta$)

A competition coefficient in the Lotka-Volterra model that converts individuals of species 1 into equivalent competitive units of species 2.

Competition Coefficient of 1 ($\alpha = 1$)

A condition in which interspecific competition is exactly equal to intraspecific competition, meaning an individual of the competing species has the same per capita competitive impact as a member of one's own species.

Population Growth Isocline

A straight line plotted on a phase graph representing combinations of species abundances where population growth rate is zero ($\frac{dN}{dt} = 0$), meaning the population neither increases nor decreases.

Species 1 Zero-Growth Isocline Endpoints

The boundary line for species 1 plotted between its carrying capacity $K_1$ on the $N_1$ axis (x-axis) and $\frac{K_1}{\alpha}$ on the $N_2$ axis (y-axis).

Species 2 Zero-Growth Isocline Endpoints

The boundary line for species 2 plotted between its carrying capacity $K_2$ on the $N_2$ axis (y-axis) and $\frac{K_2}{\beta}$ on the $N_1$ axis (x-axis).

Stable Coexistence Criterion (Lotka-Volterra)

The mathematical condition where neither species drives the other to extinction, occurring when $\alpha < \frac{K_1}{K_2} < \frac{1}{\beta}$.

Semibalanus and Chthamalus

A pair of barnacle species demonstrating how physical stress alters competitive outcomes: the larger Semibalanus outcompetes Chthamalus in lower tidal zones, but Chthamalus survives at the very top of high tide where desiccation occurs.

Fugitive Species

Species capable of rapid dispersal and rapid growth that colonize recently disturbed habitats before being excluded by superior, slower-growing competitors.

r-selected Species

Organisms that allocate energy to high reproductive output, fast growth, and effective dispersal, frequently acting as fugitive species in disturbed environments.

Competitive Reversal

An ecological phenomenon where an initially dominated species acquires an adaptive mutation over time (observed around week 50 in laboratory blowflies competing with houseflies) that allows it to outcompete and displace the previously dominant species.