KREBS chapters 9,10,11,16. Appendix III

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POPULATION DYNAMICS
KREBS chapters 9,10,11,16. Appendix
III POPULATION a group of organisms of the
same species occupying a particular space at a
particular time CHARACTERISTICS
Density Birth rate (Natality) Death rate
(Mortality) Immigration Emigration Age
distribution Sex ratio
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POPULATION DYNAMICS
Density Numbers / unit area Birth rate
(Natality) numbers of offspring / unit time Can
vary from once in a life time SEMELPAROUS to
many times ITEROPAROUS
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POPULATION DYNAMICS
Death rate (Mortality) Converse of mortality is
SURVIVAL LONGEVITY length of life SURVIVAL
can be estimated by measuring relative abundance
of two age groups provided (i) number entering
first age group and (ii) survival are both
constant
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POPULATION DYNAMICS
Immigration and Emigration are aspects of
DISPERSAL SOURCE populations births are
greater than deaths and So export individuals
emigration SINK populations births less than
deaths so numbers are maintained only by
importing individuals immigration Dispersers
link populations. METAPOPULATION a collection
of subpopulations
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LIFE TABLES
LIFE TABLE is an age-specific summary of
the birth and death rates operating on a cohort
of individuals COHORT a group of organisms
born in the same time period
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LIFE TABLES
Age interval can be any unit e.g. year, month,
week
LIFE TABLE e.g. song sparrow population Cohort
is described by x age nx number of
survivors at age x lx proportion surviving
from birth to start of age x dx number dying
during interval x to x1 qx age-specific
mortality proportion dying during age interval
x to x1
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LIFE TABLES
Age interval can be any unit e.g. year, month,
week nx number of survivors at age x lx
nx / n0 dx nx nx1 qx dx / nx
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SURVIVORSHIP CURVES
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AGE-SPECIFIC MORTALITY
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• FECUNDITY
• after maturity
• reproduction
• continues through
• life

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U.S. WOMEN 1989
FECUNDITY
Human females stop reproducing at about 45 yrs
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COHORT LIFE TABLE is the schedule of deaths of
a group born at a given time and followed
through life. TIME SPECIFIC LIFE TABLE is a
cross-section of all cohorts represented by the
frequency of the different ages in a population
at a given moment in time
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Time specific Life table
Cohort Life table
Age
Birth
t1
t2
t3
t0
Time
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TIME SPECIFIC and COHORT LIFE TABLES
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STABLE AGE DISTRIBUTION occurs when
survivorship (lx) and age-specific births (bx)
are constant in each cohort STATIONARY AGE
DISTRIBUTION a special case of stable age
distribution in that the population is
stationary because births and deaths are equal
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STATIONARY AGE DISTRIBUTION -occurs when r
0 and b d
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
Survivorship Reproduction
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
Survivorship Reproduction
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
Survivorship Reproduction
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
Survivorship Reproduction
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
Survivorship Reproduction
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
Survivorship Reproduction
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STABLE AGE DISTRIBUTION FROM LIFE TABLE
TOTAL POPULATION
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STABLE AGE DISTRIBUTION
Survivorship Fecundity