Chapter 57- Community ecology

Community

All the populations of different species that live and interact within a particular area at the same time.

Species Richness

The number of different species in a community.

Species Abundance

The number of individuals of each species in a community.

Species Diversity

A combination of richness and abundance; greater diversity often means greater resilience.

Trophic Structure

Feeding relationships and energy flow in a community, including producers, consumers, and decomposers.

Dominant Species

Species that have the most biomass or influence over environmental conditions.

Keystone Species

Species that have a disproportionately large effect on their community relative to their abundance.

Succession

The process of change in the species structure of an ecological community over time.

Competition

Occurs when two or more organisms use the same limited resource.

Intraspecific Competition

Competition between members of the same species.

Interspecific Competition

Competition between different species.

Mutualism

An interaction in which both species benefit.

Commensalism

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

Amensalism

An interaction where one species is harmed while the other is unaffected.

Niche

An organism's ecological role and lifestyle.

Niche Overlap

When two species use the same resources, potentially leading to competition.

Fundamental Niche

The potential habitat where a species could live.

Realized Niche

The actual habitat where a species lives due to competition.

Niche Partitioning

When species divide resources to reduce competition.

Competitive Exclusion

The principle that no two species can occupy the exact same niche indefinitely.

Character Displacement

Evolutionary change that reduces niche overlap.

Producers

Organisms that produce energy-rich compounds via photosynthesis, forming the base of the food web.

Primary Consumers

Herbivores that eat producers.

Secondary Consumers

Carnivores or omnivores that eat primary consumers.

Tertiary Consumers

Organisms that eat secondary consumers.

Quaternary Consumers

Top predators that have few or no predators themselves.

Decomposers

Organisms that break down dead matter, recycling nutrients back into the environment.

Top-Down Effect

Changes at the top of the food web that affect lower levels, usually driven by consumers.

Bottom-Up Effect

Changes at the bottom of the food web that affect higher levels, usually driven by resources.

Tropical Rainforest

A highly diverse community characterized by high richness and high evenness.

Coral Reef

A community with high richness and moderate to high diversity.

Invasive Species

Non-native organisms that disrupt ecosystems by outcompeting or preying on native species.

Primary Succession

Ecological succession that begins in lifeless areas, starting from bare rock.

Secondary Succession

Ecological succession that occurs in areas where soil remains after a disturbance.

Pathogens

Organisms that can reduce the dominance of a species and alter competitive relationships in communities.

Beavers

Ecosystem engineers that create wetlands by building dams, essential habitats for many species.

Honeybees

Pollinators that help flowering plants reproduce, crucial for food web stability.

Sea Otters

Keystone species that control sea urchin populations, protecting kelp forests.

Wolves

Top predators that help regulate elk populations, influencing vegetation recovery.

Starfish (Pisaster)

Predator that maintains diversity in intertidal zones by preying on mussels.

Ecological Roles of Pathogens and Parasites

They can regulate population sizes, prevent dominance of one species, and alter community structures.