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32 Cards in this Set
- Front
- Back
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population
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set of interacting individuals of the same species
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four characteristics of populations
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boundaries
density dispersal demography |
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spatial population
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delimited by physical boundaries, such as habitats
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temporal population
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delimited by generations
need to know lifespan of organism |
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crude density
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overall measure of individuals/unit of area
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ecological density
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number of individuals/unit area suitable habitat
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indirect measures of density
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vocalizations
nest counts pelt records hunting records fecal pellets |
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population dispersion
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measurement of spatial distribution of individuals within a population
clumped, uniform, random |
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uniform dispersion is often caused by
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negative interactions
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______ ______ results from positive effects of grouping
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clumped dispersion
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population demography
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a study concerned with patterns of abundance of organisms, prediction of population changes
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population demography formula
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Nfuture = Nnow + B - D + I - E
* births minus death *immigration minus emigration |
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What is the first step in constructing a life table?
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identify the ages of individuals in sample
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What are some ways of determining ages of individuals in a sample?
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skeletochronology, tooth wear, banding, ear tagging, insect instars,
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What is the second step in constructing a life table?
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2. determine the probability of individuals that live to each age (Ix).
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What is the third step in constructing a life table?
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3. Determine average number of female offspring born to each female at each age (b of x).
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what is the fourth step in constructing a life table?
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4. Multiply l of x and b of x to determine R of o (the net replacement rate).
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net replacement rate (R of o)
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tells you what Nfuture is likely to be
R of o = 1; population is stable, Nfuture = Nnow R of o > 1; population is increasing, Nfuture > Nnow R of o < 1; population is decreasing, Nfuture < Nnow |
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static life table
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A static life table contains the age groups in a population at one particular period of time. Thus, cohorts are not followed in time, but reconstructed using one-time observations.
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cohort life table
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follow same animals from birth to death
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Growth measured as instantaneous growth (dN/dt)
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dN/dt > 0, population increasing
dN/dt < 0, population decreasing |
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difference between exponential and logistic population growth curves
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exponential - shooting upward quickly
logistic - increasing gradually, then plateau |
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r-selection
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high reproductive rate
unstable environment low investment in young type 3 survival "quantity over quality" |
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k-selection
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low reproductive rate
stable environment high investment in young/parental care type 1 survival "quality over quantity" |
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community
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association of different species living together with some degree of interdependence
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a community is characterized by:
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competition
predation disturbance |
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____ promotes niche diversity.
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Competition
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______ _____ results from niche divergence.
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Adaptive radiation
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____ ____ can increase the diversity of a community.
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Keystone predators
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disturbance
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includes natural and human-caused forces that disrupt communities
vary in intensity and frequency |
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keystone species
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A keystone species is a species that plays a critical role in maintaining the structure of an ecological community and whose impact on the community is greater than would be expected based on its relative abundance or total biomass.
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intermediate disturbance hypothesis
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biodiversity is highest when disturbance is neither too rare nor too frequent
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