Community Ecology Vocabulary Flashcards

A set of vocabulary flashcards covering community ecology concepts, diversity metrics, food webs, species interactions, ecological succession, r/K selection, and latitudinal diversity gradients.

Community Ecology

The study of how populations of different species interact with each other and with their local environment.

Species Richness

The number of different species present in a biological community.

Species Evenness

The relative abundance of the different species within a biological community.

Species Diversity

A measurement of community structure that incorporates both species richness and species evenness.

Shannon-Wiener Diversity Index ($H'$)

A quantitative index used to measure species diversity, calculated as $H' = -\sum [p_i \ln(p_i)]$ (using the absolute value), where $p_i$ is the proportion of total individuals belonging to species $i$.

Ecosystem

A biological community together with the physical environment with which it interacts.

Primary Producers

Organisms (such as plants, algae, and phytoplankton) that manufacture carbohydrates via photosynthesis using sunlight, water, soil or ocean nutrients, and $\text{CO}_2$.

Grazing Food Web

A food web composed of producer, herbivore, and carnivore trophic levels through which energy and nutrients flow.

Detrital Food Web

A food web made up of detritivores and decomposers that subsist on the waste products and dead organic material produced by organisms in the grazing food web.

Direct Effects

Interactions where the action of one species directly impacts another species in a community, such as a predator killing prey or a bee pollinating a flower.

Indirect Effects

Interactions where the effect of one species on another is mediated by a third species in the community.

Trophic Cascade

An indirect effect that occurs when the introduction or removal of a top predator causes trickling-down effects across multiple lower trophic levels.

Keystone Predator

A predator species that exerts a large, indirect controlling effect on its habitat and maintains overall species diversity by preventing dominant competitors from forming a monoculture.

Pisaster ochraceus

A predatory intertidal sea star that functions as a keystone predator by consuming dominant California mussels (Mytilus californianus), preventing mussel monocultures and preserving biodiversity.

Ecological Succession

The gradual and orderly change in the species composition and structure of a biological community over time following habitat formation or disturbance.

Primary Succession

Ecological succession that begins on completely barren, lifeless ground where no soil exists (such as cooled lava flows or retreating glaciers), requiring 100s to 1000s of years to complete.

Secondary Succession

Ecological succession occurring after an existing ecosystem is disrupted or destroyed but soil, nutrients, and biological material remain intact, completing in 10s to 100s of years.

r-selected Species

Species characterized by small size, fast growth, early reproduction, high reproductive rates, and virtually no parental investment, adapting them to harsh, less competitive pioneer stages.

K-selected Species

Species characterized by larger size, slow growth, late reproduction, low reproductive rates, and high parental investment (e.g., nutrient-packed seeds), allowing survival in competitive climax communities.

Latitudinal Diversity Gradient

The large-scale ecological pattern in which species richness systematically increases from high latitudes toward the equator.