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44 Cards in this Set

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Population
The individuals that belong to the same species and live in a given area at particular time.
Exponential growth model

A growth model that estimates a population's future size (Nt) after a period of time (t), based on the intrinsic growth rate (r) and the numbers of reproducing individuals currently in the population (N0). The formula is:


rt


Nt=N0e


e is 2.72

Resource partitioning
When two species divide a resource based on differences in their behavior or morphology. Competition for a limiting resource can lead to this. In evolutionary terms, when competition reduces the ability of individuals to survive and reproduce, natural selection will favor individuals that overlap less with other species in the resources they use.
Community
All of the populations of organisms with area.
Predation
An interaction in which one animal typically kills and consumes another animal.
Population ecology
The study of factors that cause populations to increase or decrease.
Logistic growth model
A growth model that describes a population whose growth is initially exponential, but slows as the population approaches carrying capacity of the environment. Ecologists have modified the exponential growth model to incorporate environmental limits on population growth, including limiting resources.
Population size
The total number of individuals that belong within a defined area at a given time.
Mutualism
An interaction between two species that increases the chances of survival or reproduction for both species. Each species in a mutualistic interaction is ultimately assisting the other species in order to benefit itself. If the benefit is too small, the interaction will no longer be worth the cost of helping the other species.
Population density
The number of individuals per unit area at a given time.
Overshoot
When a population becomes larger than the environment's carrying capacity.
Commensalism
A relationship between species in which one species benefits and the other species is neither harmed nor helped. This is very common in nature. In contrast to other species interactions, commensalism has a positive effect on one species and no effect on the other species.
Population distribution
A description of how individuals are distributed with respect to one another.
Die-off
A rapid decline in a population due to death.
Symbiotic relationship
The relationship between two species that live in close association with each other. These kinds of relationships are all throughout the world in negative, positive, and neutral interactions.
Sex ratio
The ratio of males to females in a population.
K- selected species
A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity.
Keystone species
A species that plays a far more important role in its community than its relative abundance might suggest.
Age structure
A description of how many individuals fit into particular age categories in a population.
r-selected species
A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs.
Predator-mediated competition
Organism who reduce abundance of a superior competitor and therefore allows inferior competitors to exist.
Density-dependent factors
A factor that influences an individual's probability of survival and reproduction in a manner that depends on the size of the population.
Survivorship curves
A graph that represents the distinct patterns of species survival as a function of age.
Ecosystem engineers
A keystone species that creates of maintains habitat for other species.
Limiting resource
A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size.
Ecological succession
The predictable replacement of one group of species by another group of species over time.
Carrying capacity ( K )
The limit of how many individuals in a population the environment can sustain.
Metapopulation
A group of spatially distinct populations that are connected by occasional movements of individuals between them.
Primary succession
Ecological succession occurring on surfaces that are initially devoid of soil.
Density-independent factors
A factor that has the same effect on a individual's probability of survival and the amount of reproduction at any population size.
Community ecology
The study of interactions between species.
Secondary succession
The succession of plant life that occurs in areas that have been disturbed but have not lost their soil. It follows an event, such as a forest fire or hurricane, that removes vegetation but leaves the soil intact. It also occurs in abandoned agricultural fields.
Growth rate
The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period.
Competition
The struggle of individuals to obtain a shared limiting resource.
Pioneer species
A species that can colonize new areas rapidly and grow well in full sunshine.
Intrinsic growth rate ( r )
The maximum potential for growth of a population under ideal conditions with unlimited resources.
Competitive exclusion principle
The principle stating that two species competing for the same limiting resource cannot coexist. Under a given set of environmental conditions, when two species have the same realized niche, one species will perform better and will drive the other species to extinction.
Theory of island biogeography
A theory that demonstrates the dual importance of habitat size and distance in determining species richness.
Biotic potential
The ability of a population of living species to increase under ideal environmental conditions – sufficient food supply, no predators, and a lack of disease. An organism's rate of reproduction and the size of each litter are the primary determining factors for biotic potential.
Bottom up control
It refers to ecosystems in which the nutrient supply and productivity and type of primary producers control the ecosystem structure.
Doubling time
The number of years it takes a population to double.
Environmental resistance
The sum of the environmental factors (such as drought, mineral deficiencies, and competition) that tend to restrict the biotic potential of an organism or kind of organism and impose a limit on numerical increase.
Top down control
It refers to when a top predator controls the structure or population dynamics of the ecosystem.
Climax community
The final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference.