Glossary
Abiotic
Referring to the non-living chemical and physical parts of an environment that affect living organisms.
Example:
Sunlight, water, soil pH, and temperature are crucial abiotic factors influencing plant growth in a garden.
Biotic
Referring to the living or once-living components of an ecosystem, including all organisms and their interactions.
Example:
The trees, fungi, insects, and animals in a forest are all biotic components that interact with each other.
Carrying Capacity
The maximum number of individuals of a particular species that an environment can sustainably support indefinitely, given available resources.
Example:
The carrying capacity of a small pond for fish might be limited by the amount of dissolved oxygen or available food, preventing the population from growing indefinitely.
Commensalism
A type of symbiotic relationship between two species in which one organism benefits and the other is neither significantly harmed nor helped.
Example:
Barnacles attaching to a whale's skin benefit from transport and access to food, while the whale is largely unaffected, demonstrating commensalism.
Community
All the populations of different species that live and interact in a particular geographic area.
Example:
The community of a coral reef includes various species of fish, corals, algae, and invertebrates interacting together.
Competition
An interaction in which two or more organisms or species require the same limited resource, leading to a negative effect on at least one of them.
Example:
Two different species of birds vying for the same limited nesting sites in a tree demonstrates interspecific competition.
Consumer
An organism that obtains energy by feeding on other organisms or their organic remains.
Example:
A deer is a primary consumer because it eats plants, while a wolf is a secondary consumer because it eats deer.
Cooperation
Interactions between organisms of the same or different species that result in mutual benefit, often enhancing survival or reproduction.
Example:
A group of meerkats standing guard and alerting each other to predators is an example of cooperation within a species.
Density-Dependent Factors
Factors that limit population growth more intensely as population density increases, such as competition for resources, predation, and disease.
Example:
As a squirrel population grows denser, the spread of a contagious disease becomes a more significant density-dependent factor limiting its numbers.
Density-Independent Factors
Factors that limit population growth regardless of population density, often abiotic events like natural disasters or extreme weather.
Example:
A sudden, severe drought is a density-independent factor that can drastically reduce a plant population, regardless of how sparse or dense it was.
Ecosystem
A community of organisms and their physical, non-living environment, interacting as a functional unit.
Example:
A desert ecosystem includes cacti, lizards, snakes, and the abiotic factors like sand, extreme temperatures, and minimal rainfall.
Exponential Growth
Population growth that occurs when resources are unlimited and the growth rate is constant, resulting in a J-shaped curve.
Example:
A bacterial colony in a new petri dish with abundant nutrients will initially show exponential growth as it rapidly multiplies.
Food Web
A complex network of interconnected food chains in an ecosystem, illustrating the various feeding relationships among organisms.
Example:
A forest food web would show how deer eat plants, wolves eat deer, and decomposers break down dead organisms, linking many species.
Keystone Species
A species that has a disproportionately large effect on its environment relative to its abundance, often maintaining the structure and integrity of an ecosystem.
Example:
Sea otters are a keystone species in kelp forests because they prey on sea urchins, preventing them from overgrazing kelp and destroying the habitat.
Logistic Growth
Population growth that slows as it approaches the carrying capacity of the environment, resulting in an S-shaped curve.
Example:
A deer population introduced to a new island will experience logistic growth as it eventually faces limited food and space, causing its growth rate to decline.
Metabolism
The sum of all chemical reactions that occur in an organism to maintain life, grow, and reproduce.
Example:
A bear's body undergoes rapid metabolism to convert stored fat into energy during hibernation, allowing it to survive without food.
Mutualism
A type of symbiotic relationship between two species in which both organisms benefit from the interaction.
Example:
The relationship between bees and flowering plants, where bees get nectar and plants get pollinated, is a classic example of mutualism.
Niche
The specific role and position a species has within its ecosystem, including its habitat, resource use, and interactions with other species.
Example:
A woodpecker's niche involves drilling into trees for insects, nesting in tree cavities, and helping control insect populations.
Parasitism
A type of symbiotic relationship between two species in which one organism, the parasite, benefits by deriving nutrients at the host's expense.
Example:
A tapeworm living in the intestines of a mammal is an example of parasitism, as it absorbs nutrients from the host, causing harm.
Population
A group of individuals of the same species living in the same geographic area at the same time.
Example:
All the white-tailed deer living within a specific forest constitute a population that ecologists might study.
Predation
An ecological interaction where one organism, the predator, hunts, kills, and consumes another organism, the prey, for food.
Example:
A hawk swooping down to catch a mouse illustrates predation, a fundamental interaction in food webs.
Producer
An organism that produces its own food, typically through photosynthesis or chemosynthesis, forming the base of most food webs.
Example:
Algae in an aquatic ecosystem are producers, converting sunlight into chemical energy that supports other organisms.
Trophic Level
The position an organism occupies in a food chain or food web, indicating its primary source of energy.
Example:
In a grassland ecosystem, grass occupies the first trophic level (producer), while a rabbit eating the grass is at the second (primary consumer).