A physiological, morphological, or behavioral trait with an underlying genetic basis that enhances the survival and reproduction of its bearers in their environment.
balance of nature
The idea that natural systems tend to return to an original, preferred state after a disturbance.
biosphere
The highest level of biological organization, consisting of all living organisms on Earth plus the environments in which they live; the biosphere is located between the lithosphere and the troposphere.
community
A group of interacting species that occur together at the same place and time.
consumer
An organism that obtains its energy by eating other organisms or their remains. Compare producer.
controlled experiment
A standard scientific approach in which an experimental group (that has the factor being tested) is compared with a control group (that lacks the factor being tested).
ecology
The scientific study of interactions between organisms and their environment.
ecosystem
A community of interacting organisms plus the physical environment in which they live.
environmental science
An interdisciplinary field that incorporates concepts from the natural sciences (including ecology) and the social sciences (e.g., politics, economics, ethics), focused on how people affect the environment and how we can address environmental problems.
evolution
(1) Change in allele frequencies in a population over time. (2) Descent with modification; the process by which organisms gradually accumulate differences from their ancestors.
hypothesis
A possible answer to a question developed using previous knowledge or intuition. See scientific method.
natural selection
The process by which individuals with certain heritable characteristics tend to survive and reproduce more successfully than individuals with other heritable characteristics.
net primary production (NPP)
The amount of energy (per unit time) that autotrophs capture by photosynthesis and chemosynthesis, minus the amount used in cellular respiration.
nutrient cycling
The cyclic movement of nutrients between organisms and the physical environment.
population
A group of individuals of the same species that live within a particular area and interact with one another.
producer
An organism that can produce its own food by photosynthesis or chemosynthesis; also called a primary producer or autotroph. Compare consumer.
replicate
To perform each treatment of a controlled experiment, including the control, more than once.
scale
The spatial or temporal dimension at which ecological observations are collected.
scientific method
An iterative and self-correcting process by which scientists learn about the natural world, consisting of four steps: (1) observe nature and ask a question about those observations; (2) develop possible answers to that question (hypotheses); (3) evaluate competing hypotheses with experiments, observations, or quantitative models; (4) use the results of those experiments, observations, or models to modify the hypotheses, pose new questions, or draw conclusions.
