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18 Cards in this Set
- Front
- Back
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define population
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individuals of the same species in a given area at a given time
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what are the 5 features of a population (different than individual)
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-size (number of individuals)
-density -range (change in size over time) -age structure -genetic structure |
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define range
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areal extent of a population/species
-geographic area that a species occupies |
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what are 2 ways ranges function
-give examples of each |
-expansion: populations expand their range when their resources are abundant, or they are small in size, or they are introduced into a new environment w/o previous predators, or they have complex social interactions
ex: mollusks -contraction: chestnut have become all but eliminated in U.S. due to foreign disease from Asia |
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describe transplant experiments
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they test whether a population either never dispersed in a given area, or whether the population cannot survive in a given area
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what are the 3 types of distributions of a population within a range, and why do they occur
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-clumped
-random -even/overdispersed results from interactions |
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how do distributions become clumped
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-clumped resources
-social interactions -limited dispersal from parentals |
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how do distributions become random
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-random dispersal
-random resources |
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how do distributions become even/overdispersed
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-territorial interactions
-competition -resources even |
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describe how a distribution may change over time
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start out as clumped, then as growth increases become random due to limited resources, then become even because territorial/competitive forces drive it so
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how are density and the size of the individual within a population correlated
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negatively correlated
-the larger the organism, the more resources that organism will need; so larger organisms will exist with fewer organisms of the same size |
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what are the 4 processes that affect population size and what is the acronym?
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-birth rate (+)
-death rate (-) -immigration (+) -emigration (-) B.I.D.E. (++ - -) |
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what is the equation for exponential growth and define each variable
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dN/dt = r*N
-dN/dt is change in the number of individuals in the population over time -r is the rate of increase or growth (b - d) -N is number of individuals |
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what are the two main factors prevent exponential growth
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density independent factors
density dependent factors |
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describe the 2 density independent factors
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-catastrophic events
-weather |
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describe the 3 density dependent factors
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-resources become limited
-more susceptible to predation -disease |
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what is the equation for logistic growth
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dN/dt = r*N*(1 - N/K)
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what does the (1 - N/K) term represent in the logistic equation
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this represents intraspecific competition, which is competition between individuals of the same species within a population. As N approaches K, population growth decreases
-this terms act by decreasing birth rate or increasing death rate |
