Ecology and Ecosystem Dynamics: Key Concepts and Interactions

Species

A group of similar organisms that can breed and produce fertile offspring.

Population

A group of individuals of the same species living in the same area.

Community

All the different populations that live together in a defined area.

Ecosystem

All the organisms living in a place, together with their physical environment.

Biome

A large region characterized by a specific climate and particular types of plants and animals.

Biosphere

The part of Earth where life exists, including land, water, and atmosphere.

Autotrophs

Organisms that make their own food using sunlight or chemical energy; also called producers.

Producers

Organisms that capture energy from sunlight or chemicals to produce food.

Heterotrophs

Organisms that obtain energy by consuming other organisms; also called consumers.

Consumers

Organisms that rely on other organisms for energy and nutrients.

Herbivores

Consumers that eat only plants.

Carnivores

Consumers that eat only other animals.

Omnivores

Consumers that eat both plants and animals.

Decomposers

Organisms that break down dead matter and return nutrients to the environment.

Scavengers

Animals that consume the carcasses of other animals that have died.

Food chain

A series of steps in which organisms transfer energy by eating and being eaten.

Food web

A network of complex feeding interactions among organisms in an ecosystem.

Trophic level

Each step in a food chain or food web.

Energy pyramid

A diagram that shows the amount of energy available at each trophic level in a food chain or web.

Carbon cycle

The movement of carbon through the atmosphere, living organisms, oceans, and the Earth's crust.

Decomposition

The process by which decomposers break down organic matter into simpler compounds.

Fossil fuels

Energy-rich substances formed from the remains of ancient plants and animals.

Biotic factors

Living parts of an ecosystem.

Abiotic factors

Nonliving parts of an ecosystem

Niche

The role or function of an organism in its environment.

Resource

Anything an organism needs for survival, such as food, water, or shelter.

Resource partitioning

The division of resources so that species with similar needs can coexist.

Intraspecific competition

Competition among individuals of the same species for limited resources.

Interspecific competition

Competition between different species for the same resources.

Habitat fragmentation

The breaking of a habitat into smaller, isolated pieces.

Predation

An interaction in which one organism (the predator) kills and eats another (the prey).

Symbiosis

A close and long-term interaction between two species.

Mutualism

A symbiotic relationship in which both species benefit.

Commensalism

A symbiotic relationship in which one species benefits and the other is unaffected.

Parasitism

A symbiotic relationship in which one organism benefits at the expense of another.

Exponential growth

Growth pattern in which a population grows rapidly without limits.

Logistic growth

Population growth that slows and stops after reaching carrying capacity.

Growth rate

The rate at which a population increases or decreases in size.

Carrying capacity

The maximum number of individuals of a species that an environment can support.

Density dependent

Factors that limit population growth based on population size (e.g., food, disease).

Density independent

Factors that affect populations regardless of size (e.g., natural disasters).

Biological magnification

The increasing concentration of toxins as they move up the food chain.

Species interactions

The various ways species interact within an ecosystem (e.g., competition, predation, symbiosis).

Keystone species

A species that has a disproportionately large effect on its ecosystem's structure and function.

Trophic cascade

An ecological phenomenon triggered by the addition or removal of a top predator that affects multiple trophic levels.

Solo Hunting Benefits

Offers independence but is dangerous, has limited energy for hunting larger prey, and can't sustain a group

Group Hunting Benefits

Provides safety, teamwork, and more energy availability, but creates more noise.