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27 Cards in this Set
- Front
- Back
Populations CANT consist of
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several species
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Phrases that can characterize a population
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Interaction individuals
Age structure Density Boundaries |
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Population ecology
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the study of populations in relation to the environment: including environmental influences on population density and distribution, age structure, and variations in population size
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Population
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a group of individuals of the same species living in the same general area
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Abundance
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the total number of individuals in a population
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Density
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the number of individuals per unit area
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THREE ways to estimate density and abundance
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1. Count
2. Sampling techniques 3. Mark-recapture |
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Count
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count all individuals within boundaries of population (e.g. sea stars in tide pools)
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Sampling techniques
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to ESTIMATE population size (e.g. oak trees in 10x100 m plots)
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Mark-recapture
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trap, mark, and recapture animals (eg. dolphins, prarie dogs)
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The fundamental law of population dynamics
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there are ADDITIONS: births, immigration (combine to form population size)
and... SUBTRACTIONS: emigration and deaths |
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Equation for fundamental law of population dynamics
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change in N = (B + I) - (D + E)
B=births I=immigration D=deaths E=emmigration N=population size |
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demography
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study of the statistics of populations and how they change over time
FOCUS on birth rates and death rates |
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Change in population size during time interval=
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BIRTHS during interval-DEATHS during interval
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Equation from above
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[Change in N/Change in Time]=B-D
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Per capita birth rate (b)=
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average # births per individual during a specific time interval (ex. year)
if population = 1000 individuals, births 34/yr, b= 34/1000=.034 |
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Per capita death rate
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average # deaths per unit time per individual
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The change in population size N in an interval of time (using per capita birth and death rates)=
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change in N/change in T = bN-dN
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"r" =
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per capita rate of increase: r=b-d
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If r>0...
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population is GROWING
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If r<0...
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population is DECLINING
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Expontential growth occurs when
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resources are unlimited and the rate of increase is at its maximum
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In a J curve...
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rate of increase is constant, but population accumulates more individuals when it is large than when it is small
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Exponential growth tends to occur when:
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1. Populations are INTRODUCED to the new environment
2. Populations are REBOUNDING from a population crash |
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Populations do not
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increase forever
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Carrying capacity (K)
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maximum population size that a particular environment can support
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Rate of population growth __________ as population size (N) approaches carrying capacity (K)
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slows
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