Interspecific Competition and Community Structure

Flashcards covering key concepts, terms, and definitions related to interspecific competition, predation, symbiosis, and community structure.

Interspecific Competition

Occurs when individuals of different species compete for the same limited resource.

Consumption

A type of competition where one species uses up a resource, leaving less for another.

Preemption

A type of competition in which one species occupies space or resources first, preventing others from using them.

Overgrowth

A competition form where one species grows over another, blocking light or access to resources.

Allelopathy

When organisms release chemicals that inhibit competitors.

Lotka-Volterra Competition Model

Predicts how two species competing for resources affect each other’s population growth.

Competition Coefficient (α)

Measures how strongly one species affects another species' population growth.

Zero Net-Growth Isocline (ZNGI)

Shows population sizes where the growth rate is zero.

Competitive Exclusion Principle

States that two species cannot coexist indefinitely if they use the exact same resource in the same way.

Niche

The role of a species in an ecosystem, including resources used, habitat, and interactions with other species.

Fundamental Niche

Where a species could live without competitors or predators.

Realized Niche

Where a species actually lives, limited by competition and other interactions.

Competitive Release

Occurs when a species expands its niche after a competitor is removed.

Niche Partitioning

When species divide resources to reduce competition.

Character Displacement

When species evolve differences in traits due to competition.

Predation

When one organism (predator) kills and consumes another (prey).

Lotka-Volterra Predator-Prey Model

Describes interactions between predators and prey and predicts population cycles.

Functional Response

Describes how predator consumption changes with prey density.

Type I Functional Response

Characterized by a linear increase in prey consumption.

Type II Functional Response

Consumption increases but slows down due to handling time.

Type III Functional Response

An S-shaped curve illustrating varying consumption rates at different prey densities.

Numerical Response

Predator population increases when prey increases.

Aggregative Response

Predators move to areas where prey are abundant.

Optimal Foraging Theory

Predicts predators will choose prey that maximize energy gained per unit time.

Constitutive Defense

Always present defenses such as armor or toxins.

Induced Defense

Defenses produced only after predator attack.

Crypsis

Camouflage that helps prey blend into the environment.

Aposematism

Bright warning colors signaling toxicity.

Batesian Mimicry

Harmless species mimics harmful species.

Müllerian Mimicry

Multiple toxic species share warning coloration.

Ambush Predation

Predator waits for prey rather than actively searching.

Consumptive Effects

Predators kill and eat prey.

Nonconsumptive Effects

Predator presence changes prey behavior.

Symbiosis

Close, long-term interactions between species.

Parasitism

Interaction where one species benefits at the expense of another.

Microparasites

Small organisms that reproduce inside hosts, such as bacteria and viruses.

Macroparasites

Larger parasites that live on or inside hosts, such as worms and ticks.

Ectoparasite

Parasite that lives on the surface of the host.

Endoparasite

Parasite that lives inside the host's body.

Direct Transmission

The spread of parasites through direct contact.

Indirect Transmission

Parasites spread through vectors, the environment, or intermediate hosts.

Complex Life Cycle

A parasite life cycle that requires multiple host species.

Obligatory Parasite

A parasite that must infect a host to survive.

Facultative Parasite

A parasite that can live with or without a host.

Behavioral Avoidance

A host defense strategy to avoid parasites.

Inflammation Response

Immediate immune reaction against parasites.

Mutualism

Interaction where both species benefit.

Mycorrhizae

Mutualism between fungi and plant roots providing nutrients and water.

Microbiome

Community of microorganisms living in or on organisms that aid in digestion, immunity, and nutrient processing.

Species Richness

Total number of species in a community.

Relative Abundance

Proportion of individuals belonging to each species in a community.

Evenness

How equally individuals are distributed among species.

Shannon-Weiner Diversity Index

A metric that combines species richness and evenness to measure biodiversity.

Rank-Abundance Plot

Graph showing species rank and relative abundance.

Dominant Species

Species with the highest abundance or biomass influencing ecosystems strongly.

Keystone Species

Species with a disproportionate ecological impact relative to abundance.

Food Chain

Linear feeding sequence within an ecosystem.

Food Web

Network of interconnected food chains, representing a more realistic ecosystem structure.

Trophic Level

Position in the food chain, such as producers, herbivores, and carnivores.

Functional Group

Species that perform similar ecological roles.

Connectance

Proportion of possible feeding links that actually occur in a food web.

Indirect Effects

Effects that occur when one species affects another through a third species.

Trophic Cascades

Predators indirectly affect lower trophic levels.

Apparent Competition

When two prey species indirectly harm each other by sharing a predator.