Genetic drift 

Genetic drift is an evolutionary force, in which allelic frequency change over generation Just by chance (sampling error). 

The deviations from the expected ratios are random, the direction of change is unpredictable.

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#Id: 1979

#XL - T Zoology

Ecological density- Total number of individual divided by total useable area.

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#Id: 1980

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#Id: 5349

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R0<1, The population eventually declines to extinction 

R0=1, The population size remains constant

R0>1, The population increases

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#Id: 5350

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#Id: 5351

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λ represents the finite rate of population change over some time interval, often a year

λ = N1/N0

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#Id: 5353

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Populations grow when R0 or λ>1, populations decline when R0 or λ<1, and are at equilibrium when R0 or λ=1