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2004-20051
Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Population Ecology
Chapter 52
2004-2005AP Biology
Essential Questions How do we measure a population? How do populations change over time? What factors affect population density,
distribution & age structure? What are the limits to growth of a
population? How many humans can
the Earth support?
2004-20052
Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Populations Population
group of individuals of same species insame general area
rely on sameresources
interact interbreed
2004-2005AP Biology
First measuredensity & dispersion
What environmentalfactors affect apopulation?
Population Ecology Population Ecology
study of populations in relation toenvironment
environmental influences on populationdensity & distribution, age structure,and variations in population size
2004-20053
Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Population density How do we measure how many
individuals in a population? number of individuals in an area mark & recapture methodsHow does this work? Difficult to count a moving target
2004-2005AP Biology
Patterns of Dispersal Spacing patterns within a population
Provides insight into theenvironmental associations& social interactions ofindividuals in population
2004-20054
Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Clumped Pattern (most common)
2004-2005AP Biology
Uniform
Clumped patternsmay result from directinteractions betweenindividuals in thepopulation
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Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Changes topopulation size Adding &
removingindividuals from apopulation birth death immigration emigration
2004-2005AP Biology
What doesthis tell youabout thepopulation?
Demography Factors that affect growth & decline of
populations vital statistics & how they change over
time
Life table
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Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Survivorship curves Graphic representation of life table
Belding ground squirrel
The relatively straight lines of the plots indicate relatively constant rates ofdeath; however, males have a lower survival rate overall than females.
2004-2005AP Biology
Survivorship curves What does this tell about survival & strategy
of a species
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Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Reproductive Table Fertility schedule
age-specific summary of reproductiverates for females
2004-2005AP Biology
maximum rate =intrinsic rate of increase
Population growthchange in population = births – deaths
Exponential model (ideal conditions)dN = rmaxNdt
N = # of individualsr = rate of growtht = time period
growth increasing at constant rate
2004-20058
Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Exponential growth rate Characteristic of populations
introduced to a new environment orrebounding from a catastrophe
African elephantprotected from hunting
Whooping cranecoming back from near extinction
2004-2005AP Biology
Carrying capacity Can populations continue
to grow exponentially? Of course NOT! What sets limit?
Carrying Capacity (K) maximum population
size that environmentcan support with nodegradation of habitat
not fixed; varies withchanges in resources
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Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Logistic model of growth
2004-2005AP Biology
Logistic model of growth
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Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Life history traits K-selection = density dependent r-selection = maximize reproductive success
K-selection
r-selection
mortality constant
2004-2005AP Biology
Trade offsNumber & size of
offspringvs.
survival of offspringor parent
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Half Hollow Hills High School Ms. FogliaAP Biology
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Parental survivalThe cost of largerbroods to bothmale & femaleparents
2004-2005AP Biology
Regulation of population size Limiting factors
density independent environmental disturbances
density dependent food supply competition predators
Population cycles population
fluctuations Dungeness crabs
ocean currents & cannibalism
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Half Hollow Hills High School Ms. FogliaAP Biology
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Limits to growth Negative feedback prevents unlimited
growthDensity dependent death raterises as birth rate rises
Densityindependentdeath rate orbirth rate
What does it mean to be densitydependent or density independent?
2004-2005AP BiologyLoss of habitat, predation, climatic changes affecting food availability
Population dynamics Complex interaction of biotic & abiotic
influencesDecline of Northern Pintail
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Half Hollow Hills High School Ms. FogliaAP Biology
2004-2005AP Biology
Isle Royale studiesMoose population on small island in Lake Superior
Why so unstable?
wolvesstarvation
winter loss
2004-2005AP Biology
Predator – prey interactions Population cycles
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Half Hollow Hills High School Ms. FogliaAP Biology
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Human population
What factors have contributed tothis exponential growth pattern?
1650→500 million
2005→6 billion
2004-2005AP Biology
Human population: rate of growth
Percent increase inglobal humanpopulation (to 2003).Dashed portion ofcurve indicatesprojected data. Sharpdip in 1960s is duemainly to a famine inChina in which ~ 60million people died.
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Half Hollow Hills High School Ms. FogliaAP Biology
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Demographic comparisonsWhat do the data implyabout population growthin these countries?
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Age structure Relative number of individuals of each age
What do the data imply about population growth inthese countries?
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Half Hollow Hills High School Ms. FogliaAP Biology
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Impact: Ecological FootprintIs the human populationnear carrying capacity?
Based on land & water areaappropriated to produce allresources it consumes & toabsorb all wastes it generates
deficit surplus
K = 10–15 billion? 2005 = ~6 billion