Ecology Fundamentals

Ecology is the scientific study of the interactions between organisms and the biotic (living) and abiotic (non-living) components of their environment.

Interactions are organized into a hierarchy:

Organismal Ecology: Studies how an organism's structure, physiology, and behavior meet environmental challenges.
Population Ecology: Focuses on factors affecting population size over time.
- A population is a group of individuals of the same species living in an area.
Community Ecology: Examines interspecific interactions' effect on community structure.
- A community is a group of populations of different species in an area.
Ecosystem Ecology: Emphasizes energy flow and chemical cycling between organisms and the environment.
- An ecosystem is the community of organisms in an area and the physical factors with which they interact.
Landscape Ecology: Focuses on energy, materials, and organism exchanges across multiple ecosystems.
- A landscape is a mosaic of connected ecosystems.
Global Ecology (Biosphere): Examines the influence of energy and materials on organisms across the biosphere.
- The biosphere is the global ecosystem, the sum of all the planet’s ecosystems and landscapes.

Biotic Factors: Living or once-living organisms in an environment.
Abiotic Factors: Non-living or physical factors in the environment.
Habitat: The specific environment an organism lives in, including its biotic and abiotic surroundings.
Niche: The role an organism plays within its ecosystem (its "job").
Competitive Exclusion Principle: Two species cannot coexist indefinitely in the same ecological niche due to competition for limited resources.
Fundamental Niche: The entire range of conditions where a species could survive.
Realized Niche: The actual niche a species occupies in a community, often limited by competition.

Biomes: Earth's climate is the primary factor affecting the location of major life zones called biomes.
Ecologically Equivalent Species: Similar species evolved in different parts of the globe where physical environments are similar, occupying the same niche.
Convergent Evolution: The process by which two species develop similar characteristics despite not sharing a recent common ancestor, often due to occupying similar niches in similar environments.
Evolutionary Adaptation: Results from interactions between organisms and their environments, leading to changes in populations over generations.
Acclimation: A gradual, reversible, physiological adjustment that occurs in response to an environmental change during an individual's lifetime. It is not evolution.