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28 Cards in this Set
- Front
- Back
demographics
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statistics that describe a population (ex. size, age structure)
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population size
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the number of individuals that actually or potentially contribute to the gene pool of a population
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age structure
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of a population, the number of individuals in each age category
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reproductive base
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the number of actually and potentially reproducing individuals of a population
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population density
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number of individuals of a population in a specified volume or area of a habitat
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population distribution
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the pattern in which individuals of a population are dispersed through their habitat
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quadrats
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one of the number of sampling areas of the same size and shape used to estimate population size
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capture-recapture methods
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individuals of a mobile species are captured (or selected) at random, marked, then released so they can mix with unmarked individuals. one or more samples are taken. the ratio of marked to unmarked individuals is used to estimate total population size.
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immigration
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one or more individuals move and take up residence in another population of its species
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emigration
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permanent move of one or more individuals out of a population
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migration
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of many animals, a recurring pattern of movement between two or more regions in response to seasonal change or other environmental rhythms
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per capita growth rate
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the rate obtained by subtracting a populations per capita death rate from per capita birth rate
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zero population growth
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no net increase or decrease in population size during a specified interval
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exponential growth
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population increases in size by the same proportion of its total in each successive interval
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doubling time
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the time it takes for a population to double in size
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biotic potential
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the maximum rate of increase per individual for a population growing under ideal conditions
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limiting factors
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any essential resource that limits population growth when scarce
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logistic growth
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population growth pattern. a population grows exponentially when small, then levels off in size once carrying capacity has been reached.
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carrying capacity
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maximum number of individuals of a species that a particular environment can sustain
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density-depedent factors
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a factor that slows population growth, and either appears or worsens with crowding (ex. disease, competition for food)
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density independent factor
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a factor that slows population growth; its likelihood of occurring and magnitude of effect does not vary with population density
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life history pattern
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of a species, pattern of when and how many offspring are produced during a typical lifetime
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cohort
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a group of individuals of the same age
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survivorship curves
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plot of age-specific survival of cohort, from the time of birth until the last individual dies.
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r-selection
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selection that favors traits that maximize number of offspring; operates when the population is well below its carrying capacity
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k-selection
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selection for traits that make offspring better competitors; occurs in a population near carrying capacity.
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total fertility rate (TFR)
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for humans, the average number of children born to a female during her lifetime
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demographic transition model
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model that correlates in population growth with stages of economic development
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