3 Community Ecology Free Online FlashCards

How does an ecosystem differ from a community?

A community is interacting populations of different species in one area; an ecosystem also includes the nonliving environment, such as soil, water, and climate.

What two features generally increase a community’s species diversity?

A community generally has greater species diversity when it has more species and their abundances are more even.

What does a species’ niche describe?

A niche describes the conditions and resources a species uses, as well as its interactions with other organisms.

What makes a species a keystone species?

A keystone species has an influence on community structure that is disproportionately large relative to its abundance.

What is a foundation species?

A foundation species shapes the environment and provides resources or shelter for many other species; trees that create forest habitat are an example.

When does competition occur, and how does it affect each participant?

Competition occurs when species rely on the same limited resource, and it negatively affects both participants.

How can species with similar resource needs reduce competition and coexist?

Species can coexist by partitioning resources—for example, two bird species may feed on insects in different parts of the same tree.

How do mutualism and commensalism differ in their effects?

Mutualism benefits both species (+/+); commensalism benefits one while having little measurable effect on the other (+/0).

How can a decline in a predator indirectly affect a food web?

If a predator becomes rare, its prey may increase and consume more organisms below them in the food web, indirectly changing other populations.

How can predator–prey interactions drive evolutionary change?

Reciprocal selection over generations can shape prey defenses and predator hunting abilities.

What is ecological succession, and what often precedes it?

Ecological succession is a change in a community’s species composition over time; it often follows a disturbance that alters living conditions or removes organisms.

Where does primary succession begin, and how can pioneers help?

Primary succession begins where developed soil is absent, such as on newly exposed rock. Pioneer organisms can establish there and help contribute to soil formation.