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Populations

Populations. What is a population?. a group of actively interacting and interbreeding individuals in space and time. populations are characterized by:. -density, -distribution in space, -age structure, -sex ratio, -birth rate, -death rate, -emigration rate,

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Populations

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  1. Populations

  2. What is a population? • a group of actively interacting and interbreeding individuals in space and time.

  3. populations are characterized by: -density, -distribution in space, -age structure, -sex ratio,-birth rate, -death rate, -emigration rate, -immigration rate,-genetic structure. - Selection operates on individuals, populations evolve

  4. Density Dynamics Density change is a function of: Birth rate, immigration rate and Death rate, emigration rate

  5. Population Size • Theory of population growth

  6. Population Growth (Density Independence)‏ • Nt+1 = RNt • where Nt is the population size at time t • and R is the reproductive value • -if R=2 then populations increase as 1,2,4,8,16 etc. =2t • rewritten as Nt = Rt • - If R=1 ? If R<1 ?

  7. Life Tables

  8. Life tables Cohort vs Static x - age lx – survivorship mx –age specific fecundity R= net reproductive rate = Σ lx * mx G= generation = Σ x*lx * mx / R Assumes stable age distribution

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