Ecological Interactions: Predation, Niche Dynamics, and Prey Defenses

Vocabulary practice flashcards covering niche quantification, predation types, functional responses, population limitation, and antipredator adaptations from lecture notes.

Niche Breadth ($w$)

The standard deviation of resource use by a species along a defined resource spectrum.

Resource Distance ($d$)

The distance between two species in their average resource use along a resource spectrum.

Coexistence Ratio ($\frac{d}{w}$)

A quantitative measure of niche overlap comparing distance ($d$) to niche breadth ($w$); values of $\frac{d}{w} < 1$ result in competitive exclusion (no coexistence), whereas values of $\frac{d}{w} > 3$ permit full coexistence.

Biophagy

Predation in the broad ecological sense, encompassing carnivory, herbivory (grazing and browsing), parasitism, parasitoids, and pathogens.

Detritivores

Organisms that feed on dead plant and animal organic matter and detritus.

Functional Response Curves (FRC)

Mathematical descriptions showing the relationship between prey density and the rate of prey consumption per predator.

Threshold of Security

The minimum prey density below which no further predation occurs, typically due to predator prey-switching, decreased search efficiency, or prey finding refuges.

Compensatory Predation

Predation that removes individuals that would have otherwise died from other causes such as starvation or disease, resulting in no net reduction of prey population size.

Additive Predation

Predation that removes individuals that would have otherwise survived and reproduced, holding prey density below carrying capacity ($K$) and preventing population overshoot.

Liebig's Law of the Minimum

The ecological principle that population growth and carrying capacity are limited by the single scarcest resource or factor rather than total resources available.

Ampulex compressa

The emerald cockroach wasp, a parasitoid that delivers a precise venomous sting to the brain of its cockroach host to eliminate the escape reflex before using it to nourish its larva.

Dingo Fence Effect

An ecological barrier experiment in Australia showing high red kangaroo density where dingoes are absent and near-zero density where dingoes are present, demonstrating top-down control by predators.

Ecological Disharmony

The non-representative proportions of species and ecological roles found on islands compared to mainland sources, caused by differing dispersal capabilities and high extinction rates.

Super Predator

A term for human hunters and fishers, characterized by harvesting adult reproductive prey at median rates up to 14 times higher than non-human predators.

Crypsis

An antipredator defense involving camouflage or coloration that matches the background to prevent detection during predator search.

Aposematic Coloration

Conspicuous warning coloration displayed by toxic, venomous, or unpalatable prey to signal unpleasant consequences and train predators to avoid them.

Batesian Mimicry

A defense mechanism where a palatable or non-defended mimic species evolves visual resemblance to an unpalatable or dangerous model species.

Müllerian Mimicry

A defense mechanism where two or more unpalatable, toxic, or dangerous species evolve shared conspicuous warning color patterns, reinforcing mutual predator avoidance.

Autotomy

An antipredator defense mechanism in which an organism voluntarily releases or sheds an appendage (such as a limb or tail) to escape predator capture.

Chemical Defense (Arthropods)

The most common antipredator mechanism in arthropods (accounting for 46% of recorded mechanisms), involving toxic substances or reflexive bleeding.