The individuals that belong to the same species and live in a given area at a particular time.
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Community
All of the populations of organisms within a given area.
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ecosystem
all biotic and abiotic factors in an area
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biosphere
Consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere.
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density dependent factors
A limiting factor of a population wherein large, dense populations are more strongly affected than small, less crowded ones.
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density-independent factors
limiting factor that affects all populations in similar ways, regardless of population size
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overshoot
when a population becomes larger than the environment's carrying capacity
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dieoff/dieback
a rapid decline in a population due to death
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negative feedback loop
dampens or buffers changes; this tends to bring the system to its equilibrium state, making it more stable.
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positive feedback loop
enhances or amplifies changes; this tends to move a system away from its equilibrium state making it more unstable.
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LD50
the point at which 50 percent of the test organisms die from a toxin.
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exponetial population growth
when the size of each generations offspring is larger than the generation before it
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logistic population growth
population growth that levels off as population size approaches carrying capacity
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metapopulations
a group of spatially distinct populations that are connected by the occasional movements of individuals between them
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population size
the number of individuals in a population
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corridors
a strip of natural habitat that connects separated populations
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population density
Number of individuals per unit area
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population dispersion
the way in which individuals of a population are spread out over an area or volume
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population distribution
a description of how individuals are distributed with respect to one another
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population sex ratio
the ratio of males to females in a population
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population age structure
Determines future growth potential (via individuals of reproductive age)
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K-selected species
a species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity.
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r-selected species
a species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs.
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K-selected species characteristics
large, long lives, few offspring, slow reproductive speed, type I, and parental care
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r-selected species characteristics
small, short lives, many offspring, fast reproductive speed, type III, land little parental care
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Type I survivorship curve
a pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age
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Type II survivorship curve
a pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span
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Type III suvivorship curve
a pattern of low survivorship throughout the individuals life, few reach adulthood
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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
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resource partitioning
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
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predators
animals that kill and eat other animals; eating most of what they kill
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Herbivores
Consumers that eat only plants
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Parasites
An organism that lives in or on another organism, deriving nourishment at the expense of its host
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predation
the use of one species as a resource by another species
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keystone species
a species on which other species in an ecosystem largely depend, such that if it were removed, the ecosystem would change drastically.
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ecological succession
series of gradual changes that occur in a community following a disturbance
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calculating exponential growth
N(0)*e^(r*t)
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Mutualism
A relationship between two species in which both species benefit
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Commensalism
A relationship between two organisms in which one organism benefits and the other is unaffected
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symbiotic relationship
the relationship of two species that live in close association with each other
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predator-mediated competition
competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist
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ecosystem engineers
a keystone species that creates or maintains habitat for other species
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primary succession
An ecological succession that begins in an area where no biotic community previously existed. Areas devoid of soil (rocks), break up over time forming soil.
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secondary succession
Succession follows a disturbance that destroys a community without destroying the soil. (climax community)
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pioneer species
First species to populate an area during primary succession
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island biogeography
The study of rates of colonization and extinction of species on islands or other isolated areas based on size, shape, and distance from other inhabited regions
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Climax community
***An ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment***.
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carrying capacity
The largest number of individuals in a population that an environment can support with its available resources
Studied by 36 people
