chapter 52
DESCRIPTION
CHAPTER 52. POPULATION ECOLOGY. Characteristics. Density Distribution Size Age Structure. Density. Direct Counts- Larger, less numerous organisms Plankton Population Sampling Time x velocity x diameter = M 3 Total # of plankton/ M 3 = # plankton per M 3 - PowerPoint PPT PresentationTRANSCRIPT
CHAPTER 52CHAPTER 52
POPULATION ECOLOGYPOPULATION ECOLOGY
CharacteristicsCharacteristics
DensityDensity DistributionDistribution Size Size Age StructureAge Structure
DensityDensity
Direct Counts- Direct Counts- – Larger, less numerous organismsLarger, less numerous organisms
Plankton Population SamplingPlankton Population Sampling– Time x velocity x diameter = MTime x velocity x diameter = M33
– Total # of plankton/ MTotal # of plankton/ M3 3 = # plankton per M= # plankton per M33
– 75 plankton/0.5 M75 plankton/0.5 M33 = 150/M = 150/M33
Mark & Recapture- many animalsMark & Recapture- many animals Aerial Surveys – Aerial Surveys –
– Line transects etc.Line transects etc.– observe large areas, large animals by sightobserve large areas, large animals by sight
Mist nets for migrating birdsMist nets for migrating birds
Mark & RecaptureMark & Recapture
# marked in 1# marked in 1stst catch catch = = # recaptures in 2# recaptures in 2ndnd catch catch
Population total total # in 2Population total total # in 2ndnd catch catch
OR:OR:
N = N = # marked in 1# marked in 1stst catch x total # in 2 catch x total # in 2ndnd catch catch # of recaptures in 2# of recaptures in 2ndnd catch catch
# marked = 50 Total in 2# marked = 50 Total in 2ndnd catch = 100 # catch = 100 # recaptures = 10recaptures = 10
N = 50 x 100/10 N = 500N = 50 x 100/10 N = 500
DispersionDispersion
How the individuals are arranged in the How the individuals are arranged in the landscape.landscape.
Uniform – Uniform – – all parts of the habitat suitable, but has intra-all parts of the habitat suitable, but has intra-
specific competitionspecific competition Random Random
– all parts of habitat suitableall parts of habitat suitable Clumped-Clumped-
– Habitat is patchy orHabitat is patchy or– Social behaviorsSocial behaviors
DispersionDispersion
Population SizePopulation Size
Starting size of populationStarting size of population Add: Births and immigrationAdd: Births and immigration Subtract: Deaths and emigrationSubtract: Deaths and emigration Gives the New population size, Gives the New population size,
Population GrowthPopulation Growth
TimeTime # Females# Females Eggs/FemaleEggs/Female # Flies# Flies
11 11 100100 100100
22 5050 100100 5,0005,000
33 2,5002,500 100100 250,000250,000
44 125,000125,000 100100 12,500,00012,500,000
55 6,250,0006,250,000 100100 625,000,000625,000,000
66 312,000,000312,000,000 100100 31,250.000,00031,250.000,000
77 15,625,000,00015,625,000,000 100100 1,563,500,000,0001,563,500,000,000
Growth curve for fieldMice in a cornfield
Exponential Exponential GrowthGrowth
Fig. 9.4, p. 201
Time (t)
Po
pu
lati
on
siz
e (N
)
Exponential Growth
Exponential GrowthExponential Growth
Biotic Potential – Pop. Biotic Potential – Pop. Grows as fast as Grows as fast as physiology allows.physiology allows.
Unlimited resourcesUnlimited resources No pollution build upNo pollution build up Ideal conditionsIdeal conditions Short lived periodShort lived period Often quickly die out, Often quickly die out,
colonize new areascolonize new areas R selected speciesR selected species
Logistic GrowthLogistic Growth
Time (t)P
op
ula
tio
n s
ize
(N)
K
Logistic Growth
Logistic GrowthLogistic Growth Slower initial Slower initial
growthgrowth Long –term stable Long –term stable
pop. At carrying pop. At carrying capacity (K).capacity (K).
K is size of pop. K is size of pop. Area can sustain.Area can sustain.
Growth slowed by Growth slowed by limiting factorslimiting factors
Fig. 32.2Fig. 32.2
Population Limiting FactorsPopulation Limiting Factors Density dependent Density dependent
factorsfactors– CompetitionCompetition– PredationPredation– Stress/crowdingStress/crowding– Waste accumulationWaste accumulation– DiseaseDisease– SpaceSpace– ResourcesResources
Density independent Density independent factorsfactors– Weather/climateWeather/climate– Periodic disturbancesPeriodic disturbances
Population Life History StrategiesPopulation Life History Strategies
R
K
Type I vs Type IIIType I vs Type III
Type III Type III (R selected)(R selected)– Short maturation & Short maturation &
lifespanlifespan– Many offspringMany offspring– No parental careNo parental care– High death rateHigh death rate
Type I Type I (K selected)(K selected)– Long maturation & Long maturation &
lifespanlifespan– Few offspringFew offspring– Extensive parental Extensive parental
carecare– Low death rateLow death rate
Fewer, larger offspringHigh parental care and protection of offspringLater reproductive ageMost offspring survive to reproductive ageLarger adultsAdapted to stable climate and environmental conditionsLower population growth rate (r)Population size fairly stable and usually close to carrying capacity (K)Specialist nicheHigh ability to competeLate successional species
elephant saguaro
K-Selected Species
r-Selected Species
cockroach dandelion
Many small offspringLittle or no parental care and protection of offspringEarly reproductive ageMost offspring die before reaching reproductive ageSmall adultsAdapted to unstable climate and environmental conditionsHigh population growth rate (r)Population size fluctuates wildly above and below carrying capacity (K)Generalist nicheLow ability to competeEarly successional species
European KestralsEuropean Kestrals
r selectedr selected– Population grows at Population grows at
biotic maxbiotic max– Lots of offspringLots of offspring– Little parental careLittle parental care– Reproduce early, Reproduce early,
oftenoftenK selectedK selected– Population adapted Population adapted
to being at carrying to being at carrying capacitycapacity
– Few offspringFew offspring– Lots of parental careLots of parental care– Reproduce late, Reproduce late,
infrequentlyinfrequently
TestingTestingaa
hypothesishypothesis
Human Population GrowthHuman Population Growthoror
Go Forth and MultiplyGo Forth and Multiply
Human Population growthHuman Population growth For most of our history a logistic curve.For most of our history a logistic curve. Currently exponential growthCurrently exponential growth
– Not uniform around the globeNot uniform around the globe– Developing nations growing fastest Developing nations growing fastest
What has made the change possible?What has made the change possible?– Drop in death rate. Birth rate has fallen, not Drop in death rate. Birth rate has fallen, not
increased.increased. How long will this be sustainable?How long will this be sustainable? Future predictions for growth?Future predictions for growth?
Human Population GrowthHuman Population Growth
World – Wide Trend??World – Wide Trend??
Growth rates differ within and Growth rates differ within and between countries:between countries:
Births per woman
< 2
2-2.9
3-3.9
4-4.9
5+
Data notavailable
Births per woman
Infant deaths per 1,000live births
<10
10-35
36-70
71-100
100+Data notavailable
Infant deaths
Fig. 11.3, p. 240
<1%
1-1.9%
2-2.9%
3+%
Data notavailable
Annual worldpopulation growth
Population Growth
GNP per capita, 1998
Low income (Under $1,000)
Middle income ($1,000–$10,000)
High income (Above $10,000)
Fig. 1.5, p. 9
Income and country
Rapid Growth Slow Growth Zero Growth Negative Growth
General age structure diagrams
Canada United States
India Australia
Mexico China
Males Females Males Females
Age
Females Males
1955
20
20
Millions24
24
1985
Millions24
24
2035
Millions
2015
24
24
Millions
Yellow= Baby BoomersYellow= Baby Boomers
USA age structure DiagramsUSA age structure Diagrams
NOW WHAT?NOW WHAT?
Where we are:Where we are:
1930, 2 billion1930, 2 billion September 1999, 6 billionSeptember 1999, 6 billion
– 3 people every second3 people every second– 250,000 every day250,000 every day– 87 million every year87 million every year
–12 billion by 2050 12 billion by 2050 –8 Billion- if slower rate8 Billion- if slower rate
Influence on environmentInfluence on environment More land for agriculture, resource More land for agriculture, resource
exploitationexploitation More land for cities, roadways, suburbsMore land for cities, roadways, suburbs Less fish in the sea for the food chainLess fish in the sea for the food chain DeforestationDeforestation Oil, gas won’t last foreverOil, gas won’t last forever Pollution builds upPollution builds up Better “green” technologies?Better “green” technologies? Heightened awareness, concern?Heightened awareness, concern? Better understanding of ecosystems?Better understanding of ecosystems?
Human disturbance
Tropic of Capricorn
Equator
Predominantly naturalPartially disturbedHuman dominated
AntarcticCircle
Tropic ofCancer
ArcticCircleArcticCircle
Human domination of landscape
Every second… 5 people are born
and 2 people die,
a net gain of 3 people.
Improved medical care has dramatically reduced infant mortality and mortality of
women during labor.
Demographic transitionDemographic transition
Larger urban families cost more, birth rate Larger urban families cost more, birth rate dropsdrops
Population now much larger, slows its growth Population now much larger, slows its growth raterate
Influence of other (cultural, religious) pressures Influence of other (cultural, religious) pressures can slow birth rate declinecan slow birth rate decline
Women often lack freedom to determine family Women often lack freedom to determine family size, education employment opportunitiessize, education employment opportunities
Demographic transitionDemographic transition Death rate (infant mortality) drops firstDeath rate (infant mortality) drops first Birth rate remains constantBirth rate remains constant Population increases quicklyPopulation increases quickly Economy transitions from agriculture to urbanEconomy transitions from agriculture to urban
Stage 1 Preindustrial
Stage 2 Transitional
Stage 3 Industrial
Stage 4 Postindustrial
births
deaths
relative population
size
low increasing very high
decreasing low zero negative
3230282624222018161401910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010B
irth
s p
er t
ho
usa
nd
po
pu
lati
on
Demographictransition Depression Baby boom Baby bust Echo baby boom
World War II
Year
USA demographic transition & population size
4.0
3.5
3.0
2.5
2.02.1
1.5
1.0
0.5
01920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Bir
ths
per
wo
man
Total fertility rates in USA 1917-2000
Baby Boom(1946-64)
1975 on ….Below native replacement rate- immigration keeps population growing
19071914New laws restrict immigration
Great Depression
Legal immigration to the United States between 1820 and 1997