Lecture XV - Population Processes_1

Lecture XV - Population Processes_1 - Lecture XV...

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Lecture XV – Populations, Population Processes, and Population Regulation
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What is a Population? What is a population? A population is generally defined as a group of individuals of one species living in a defined area Boundaries of the area may be natural or arbitrary (depending on the purpose of the study being undertaken) Sometimes implies breeding
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However… One may count populations of anything – leaves on a single tree, all leaves, flowering stems, etc. One may distinguish between genetic individuals (genets) and apparently or actually independent parts that share the same genotype (ramets of a genet). Always best to specify what you mean.
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Defining Population Boundaries Duckweeds Hydra and bud Flowers from a rosette (or the # of rosettes) of this saxifrage. Polyps in a coral (or the # of colonies)
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Distribution of Individuals in a Population Individual in population may be distributed in a number of ways: Random: determined by multiple factors Uniform: usually determined by competition Clumped: usually determined by resource distribution or social interactions (sometimes by low movement)
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Population Dynamics Populations are determined by 4 processes: N = B irth + I mmigration - D eath - E migration Also known as the BIDE model of population dynamics However, models of population dynamics are determined at their basic level by individual life histories
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Population Dynamics While they are described sometimes as though they were at the individual scale, life cycles and histories are population-level phenomena These phenomena describe the dynamics of populations To actually monitor population dynamics is to look at the fate of a single cohort This would enable us to estimate basic population dynamics variables such as birth rate and reproductive rate
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Back to Population Dynamics Populations are determined by 4 processes: N = B irth + I mmigration - D eath - E migration For simplicity’s sake, we will first look at dynamics of closed populations, i.e., populations that are regulated only by births and deaths, where: dN/dt = B irth - D eath
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Population Dynamics If we estimate the change in a population across an interval of time Δt, it looks like this: Per Capita (per individual in the population) birth and death rates: N t t N t B D ( ) ( ) + = + - 1 ( ) ( ) ( ) 1 ( ) ( ) ( ) B t b t t N t D t d t t N t = =
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Generalized A generalized model of population change: Or, if r = ( B D ): Population as a function of time: ( 29 N D B dt dN × - = rN dt dN = rt t e N N 0 =
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We use an example based on the life history of a iteroparous species, the great tit ( Parus major ) Population per hectare (100x100 m) is in squares; % survival in triangles. 50% of adults live to
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This note was uploaded on 01/23/2010 for the course BIOS 230 taught by Professor Gibbons during the Fall '08 term at Ill. Chicago.

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Lecture XV - Population Processes_1 - Lecture XV...

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