Communities and Ecosystems

Vocabulary practice flashcards covering community structure, interspecific interactions, trophic levels, ecological succession, and ecosystem dynamics from Chapter 37 of Campbell Biology.

Biological Community

An assemblage of all the populations of organisms living close enough together for potential interaction.

Community Dynamics

The variability or stability in the species composition of a community caused by biotic and abiotic factors.

Interspecific Interactions

Relationships with individuals of other species in a community that greatly affect population structure and dynamics.

Interspecific Competition

A relationship (classified as $-/-$) that occurs when populations of two different species compete for the same limited resource.

Mutualism

A type of interspecific interaction where both populations benefit ($+/+$).

Predation

An interaction where one species (the predator) kills and eats another (the prey) ($+/-$).

Herbivory

An interaction where an animal consumes plant parts or algae ($+/-$).

Parasitism

A relationship where host plants or animals are victimized by parasites or pathogens ($+/-$).

Ecological Niche

The sum of an organism’s use of the biotic and abiotic resources in its environment.

Mechanical and Chemical Defenses

Protective strategies used by prey or plants to adapt against predators or herbivores, such as toxins, camouflage, or thorns.

Pathogens

Disease-causing microscopic parasites, including bacteria, viruses, fungi, or protists.

Trophic Structure

A pattern of feeding relationships in a community consisting of several different levels.

Food Chain

The sequence of food transfer up the trophic levels, moving chemical nutrients and energy from producers upward.

Producers

Autotrophs that support all other trophic levels in an ecosystem.

Primary Consumers

Herbivores that consume producers.

Secondary Consumers

Organisms that typically eat herbivores on land or zooplankton in aquatic ecosystems.

Tertiary and Quaternary Consumers

Organisms that eat secondary and tertiary consumers, respectively.

Detritivores

Organisms that derive their energy from detritus, which is dead material produced at all trophic levels.

Decomposers

Mainly prokaryotes and fungi that secrete enzymes to digest organic materials and convert them into inorganic forms through decomposition.

Food Web

A network of interconnecting food chains that provides a more realistic view of a community's trophic structure.

Species Richness

A component of species diversity representing the number of different species in a community.

Relative Abundance

A component of species diversity representing the proportional representation of a species in a community.

Keystone Species

A species whose impact on its community is larger than its biomass or abundance indicates, holding the rest of the community in place (e.g., Pisaster sea stars).

Ecological Succession

The process by which a disturbed area is colonized by a variety of species, which are gradually replaced by a succession of other species.

Primary Succession

Succession that begins in a virtually lifeless area with no soil, such as rubble left by a retreating glacier or fresh volcanic lava flows.

Secondary Succession

Succession that occurs when a disturbance destroys an existing community but leaves the soil intact.

Invasive Species

Organisms introduced into non-native habitats by human actions that establish themselves at the expense of native communities.

Ecosystem

Consists of all the organisms in a community and the abiotic environment with which the organisms interact.

Energy Flow

The unidirectional movement of energy through the components of an ecosystem.

Chemical Cycling

The transfer of materials (chemical elements) within an ecosystem.

Primary Production

The amount of solar energy converted to chemical energy (in organic compounds) by producers for a given area and time period.

Biomass

The amount, or mass, of living organic material in an ecosystem.

Pyramid of Production

A diagram illustrating the cumulative loss of energy with each transfer in a food chain; typically only about $10\%$ of energy is passed to the next level.

Biogeochemical Cycles

Cycles that include biotic and abiotic components and reservoirs where chemicals accumulate outside of living organisms.

Nitrogen Fixation

The process carried out by bacteria that converts $N_2$ to nitrogen compounds (like $NH_4^+$) that can be used by plants.

Eutrophication

A process where aquatic ecosystems accumulate nutrients from land runoff, leading to increased primary production and oxygen depletion.

Sustainability

The goal of developing, managing, and conserving Earth’s resources in ways that meet current needs without compromising the ability of future generations to meet theirs.