Transcript Populations Dynamics

Population Dynamics
(Chapter 10)
1950
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Estimating Patterns of Survival
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Three main methods of estimation:
 Cohort life table
 Identify individuals born at same time
and keep records from birth.
 Static life table
 Record age at death of individuals.
 Age distribution
 Calculate difference in proportion of
individuals in each age class.
 Assumes differences from mortality.
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Survivorship Curves
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Type I: Majority of mortality occurs among
older individuals.
 Dall Sheep
Type II: Constant rate of survival throughout
lifetime.
 American Robins
Type III: High mortality among young,
followed by high survivorship.
 Sea Turtles
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Age Distribution
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Age distribution of a population reflects its history
of survival, reproduction, and growth potential.
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Age Distribution
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Rio Grande Cottonwood populations (Populus
deltoides wislizenii) are ….
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Dynamic Population in a Variable Climate
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Grant and Grant studied Galapagos Finches.
Responsiveness of population age structure to
environmental variation.
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Blacknose dace (Rhinichthys atratulus)
South Branch Codorus Creek
D-NFSTP
U-NFSTP
Blacknose Dace
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M 7
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Frequency
Frequency
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700 Million Years of Eating DNA:
A Conserved Competence Regulon in Gamma-Proteobacteria.
Dr. Andrew Cameron
Microbiology Department
University of British Columbia, Vancouver, B.C.
Tuesday, March 6th, at 4:30 – 5:30 p.m.
Ruhl Student Center, Community Room
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Rates of Population Change
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Birth Rate: Number of young born per
female; seeds per individual plant.
Fecundity Schedule: Tabulation of birth rates
for females of different ages.
“Life Table” of survivorship per age grouping
(see above) combined with fecundity
schedule can be used to calculate net
reproductive rates.
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Estimating Rates for an Annual Plant
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Phlox drummondii (phlox)
 Ro = Net reproductive rate; Average number
of seeds produced by an individual in a
population over lifetime (“birth rate”).
 Ro=∑ lxmx
 X= Age interval in days.
 lx = % pop. surviving to each age (x).
 mx= Average number seeds produced by
each individual in each age category.
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Estimating Rates for an Annual Plant
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Because P. drummondii has non-overlapping
generations, we can estimate growth rate.
 Geometric Rate of Increase (λ):
 λ=N t+1 / Nt
 N t+1 = Size of population at future time.
 Nt = Size of population at some earlier
time.
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Estimating Rates when Generations Overlap
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Common Mud Turtle (K. subrubrum)
 About half turtles nest each year.
 Average generation time:
T = ∑ xlxmx / Ro
 X= Age in years
 Per Capita Rate of Increase:
r = ln Ro / T
 ln = Base natural logarithms
fwie.fw.vt.edu/VHS/Kinosternon_subrubrum.htm
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Dispersal
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Africanized Honeybees
 Honeybees (Apis melifera) evolved in
Africa and Europe and have since
differentiated into many locally adapted
subspecies.
 Africanized honeybees disperse much
faster than European honeybees.
 Within 30 years they occupied most
of South America, Mexico, and all of
Central America.
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Africanized Honeybees
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Collared Doves
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Collared Doves, Streptopelia decaocto,
spread from Turkey into Europe after 1900.
 Dispersal began suddenly.
 Not influenced by humans.
 Took place in small jumps.
 45 km/yr
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Collared Doves
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Rapid Changes in Response to Climate Change
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Tree species began to spread northward
about 16,000 years ago following retreat of
glaciers and warming climate.
 Evidence found in preserved pollen in lake
sediments.
 Movement rate 100 - 400 m/yr.
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Rapid Changes in Response to Climate Change
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Dispersal in Response to Changing Food Supply
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Holling observed
numerical
responses to
increased prey
availability.
 Increased
prey density
led to
increased
density of
predators.
 Birds moved.
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