(ecology) a group of interdependent organisms inhabiting the same region and interacting with each other
The study of populations in relation to the environment, including environmental influences on population density and distribution, age structure, and variations in population size.
Number of individuals in a specified portion of a habitat. (Refers to how many individuals are in an area, not how they are dispersed)
Percentage of the population (or number of people of each sex) at each age level in a population.
Limiting factors (such as competition, predation, parasitism, and disease) that are affected by the number of individuals in a given area
A particular natural resource that, when limited, determines the carrying capacity of an ecosystem for a particular species
A limiting factor whose effects on a population are constant regardless of population density.
An expression of the increase in the size of an organism or population over a given period of time
intrinsic growth rate
the maximum potential for growth of a population under ideal conditions with unlimited resources
Curve with a shape similar to that of the letter J; can represent prolonged exponential growth. See exponential growth.
logistic growth model
A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.
Leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow.
a rapid decline in population size when carrying capacity is exceeded and resources are limited
Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.
Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period.
They show the likelihood of survival at different ages throughout the lifetime of the organism.
A strip of natural habitat that connects two adjacent nature preserves to allow migration of organisms from one place to another
A collection of populations that have regular or intermittent gene flow between geographically separate units
The study of how interactions between species affect community structure and organization
competitive exclusion principle
Ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time
The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species
A relationship between two organisms of different species where one benefits and the other is neither harmed nor benefited
Competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist.
an organism that causes changes in the physical environment sufficient to influence the structure of landscapes, ecosystems, or communities.
(ecology) the gradual and orderly process of change in an ecosystem brought about by the progressive replacement of one community by another until a stable climax is established
An ecological succession that begins in an area where no biotic community previously existed
Succession following a disturbance that destroys a community without destroying the soil
theory of island biogeography
The number of species found on an island is determined by a balance between two factors: the immigration rate (of species new to the island) from other inhabited areas and the extinction rate (of species established on the island). The model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of different species (species diversity).