Unit 8 Reference: Interactions, Diversity, and Change

Community Ecology

The study of how populations of different species interact within a specific area.

Interspecific Interaction

Relationships between individuals of different species that affect their survival and reproduction.

Competition

An interaction where both species are harmed as they fight for limited resources.

Predation

An interaction where one species (predator) kills and eats another (prey).

Herbivory

An interaction where a consumer eats a plant or alga, causing harm but allowing the plant to survive.

Parasitism

An interaction where a parasite derives nourishment from a host, harming but usually not killing it immediately.

Mutualism

An interaction where both species benefit from their relationship.

Commensalism

An interaction where one species benefits and the other is unaffected.

Competitive Exclusion Principle

If two species compete for the same limiting resource, one will eventually outcompete and eliminate the other.

Resource Partitioning

The differentiation of ecological niches that enables similar species to coexist.

Ecological Niche

The sum of a species' use of the biotic and abiotic resources in its environment.

Fundamental Niche

The potential niche occupied by a species if there were no competition.

Realized Niche

The portion of the fundamental niche that a species actually occupies due to competition.

Biodiversity

A measure of the variety of life at the genetic, species, and ecosystem levels.

Species Richness

The total number of different species in a community.

Species Evenness

The relative abundance of each species in a community.

Simpson's Diversity Index

Index used to calculate biodiversity, where values closer to 1 indicate higher biodiversity.

Keystone Species

A species that has a disproportionately large effect on its environment relative to its abundance.

Dominant Species

The most abundant species within a community.

Invasive Species

Non-native species introduced to a new environment that spread widely and cause harm.

Primary Succession

Succession that occurs in a lifeless area where soil has not yet formed.

Pioneer Species

Species like lichens and mosses that colonize bare rock and help form soil.

Secondary Succession

Succession that occurs where an existing community has been cleared but the soil is left intact.

Cyclic Oscillations

Fluctuations in predator and prey populations, with increases and decreases often following one another.

Natural Disruptions

Ecosystem disruptions caused by events such as storms or volcanic eruptions.

Human Disruptions

Ecosystem disruptions caused by human activities such as logging or pollution.