AP Biology
Population Ecology
population
ecosystem
community
biosphere
organism
AP Biology
Life takes place in populations
 Population
 group of individuals of same species in
same area at same time
...
AP Biology
Why Population Ecology?
 Scientific goal
 understanding the factors that influence the
size of populations
 ...
AP Biology
 Abiotic factors
 sunlight & temperature
 precipitation / water
 soil / nutrients
 Biotic factors
 other ...
AP Biology
Characterizing a Population
 Describing a population
 population range
 pattern of spacing
 density
 size ...
AP Biology
Population Range
 Geographical limitations
 abiotic & biotic factors
 temperature, rainfall, food, predators...
AP Biology
Changes in range
 Range expansions & contractions
 changing environment
Woodlands
Grassland, chaparral,
and d...
AP Biology
At risk populations
 Endangered species
 limitations to range / habitat
 places species at risk
Socorro
isop...
AP Biology
Population Spacing
 Dispersal patterns within a population
uniform
random
clumped
Provides insight into the
en...
AP Biology
Clumped Pattern (most common)
AP Biology
Uniform
Clumped patterns
May result from
direct interactions
between individuals
in the population
→ territoria...
AP Biology
Population Size
 Changes to
population size
 adding & removing
individuals from a
population
 birth
 death
...
AP Biology
Population growth rates
 Factors affecting population growth rate
 sex ratio
 how many females vs. males?
 ...
AP Biology
Life tableLife table
Demography
 Factors that affect growth & decline of
populations
 vital statistics & how ...
AP Biology
Survivorship curves
 Graphic representation of life table
Belding ground squirrel
The relatively straight line...
AP Biology
Age structure
 Relative number of individuals of each age
What do these data imply about population growth
in ...
AP Biology
Survivorship curves
 Generalized strategies
What do these graphs
tell about survival &
strategy of a species?
...
AP Biology
Trade-offs: survival vs. reproduction
 The cost of reproduction
 increase reproduction may decrease survival
...
AP Biology
Parental survival
Kestrel Falcons:
The cost of larger
broods to both male
& female parents
AP Biology
Reproductive strategies
 K-selected
 late reproduction
 few offspring
 invest a lot in raising offspring
 ...
AP Biology
Trade offs
Number & size of offspring
vs.
Survival of offspring or parent
Number & size of offspring
vs.
Surviv...
AP Biology
Life strategies & survivorship curves
0 25
1000
100
Human
(type I)
Hydra
(type II)
Oyster
(type III)
10
1
50
Pe...
AP Biology
Population growth
change in population = births – deaths
Exponential model (ideal conditions)
dN = riN
dt
N = #...
AP Biology
African elephant
protected from hunting
Whooping crane
coming back from near extinction
Exponential growth rate...
AP Biology
Regulation of population size
 Limiting factors
 density dependent
 competition: food, mates,
nesting sites
...
AP Biology
Introduced species
 Non-native species
 transplanted populations grow
exponentially in new area
 out-compete...
AP Biology
Zebra mussel
ecological & economic damage
~2 months
 reduces diversity
 loss of food & nesting sites
for anim...
AP Biology
Purple loosestrife
19681968 19781978
 reduces diversity
 loss of food & nesting sites
for animals
 reduces d...
AP Biology
K =
carrying
capacity
K =
carrying
capacity
Logistic rate of growth
 Can populations continue to grow
exponent...
AP Biology
500
400
300
200
100
0
200 10 30 5040 60
Time (days)
Numberofcladocerans
(per200ml)
 Maximum
population size
th...
AP Biology
Changes in Carrying Capacity
 Population cycles
 predator – prey
interactions
At what
population level is the...
AP Biology
Human population growth
What factors have contributed to
this exponential growth pattern?
What factors have con...
AP Biology
Distribution of population growth
1
2
3
Time
19501900 2000
Developing countries
2050
4
5
6
7
8
9
10
11
0
Develo...
AP Biology
Ecological Footprint
30.2
15.6
6.4
3.7
3.2
2.6
USA
Germany
Brazil
Indonesia
Nigeria
India
Amount of land requir...
AP Biology
Ecological Footprint
Based on land & water area
used to produce all resources
each country consumes & to
absorb...
AP Biology 2007-2008
Any
Questions?
AP Biology
Difficult to count a moving target
Measuring population density
 How do we measure how many
individuals in a p...
AP Biology
Evolutionary adaptations
 Coping with environmental variation
 regulators
 endotherms
 homeostasis
 (“warm...
AP Biology
Bright blue marble spinning in space
Ecology
AP Biology
biosphere
ecosystem
community
population
Studying organisms in their environment
organism
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16 ch53populationecology2008

  1. 1. AP Biology Population Ecology population ecosystem community biosphere organism
  2. 2. AP Biology Life takes place in populations  Population  group of individuals of same species in same area at same time  rely on same resources  interact  interbreed  rely on same resources  interact  interbreed Population Ecology: What factors affect a population?Population Ecology: What factors affect a population?
  3. 3. AP Biology Why Population Ecology?  Scientific goal  understanding the factors that influence the size of populations  general principles  specific cases  Practical goal  management of populations  increase population size  endangered species  decrease population size  pests  maintain population size  fisheries management  maintain & maximize sustained yield QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
  4. 4. AP Biology  Abiotic factors  sunlight & temperature  precipitation / water  soil / nutrients  Biotic factors  other living organisms  prey (food)  competitors  predators, parasites, disease  Intrinsic factors  adaptations Factors that affect Population Size
  5. 5. AP Biology Characterizing a Population  Describing a population  population range  pattern of spacing  density  size of population 1937 1943 1951 1958 1961 1960 19651964 1966 1970 1970 1956 Immigration from Africa ~1900 Equator range density
  6. 6. AP Biology Population Range  Geographical limitations  abiotic & biotic factors  temperature, rainfall, food, predators, etc.  habitat adaptations to polar biome adaptations to polar biome adaptations to rainforest biome adaptations to rainforest biome
  7. 7. AP Biology Changes in range  Range expansions & contractions  changing environment Woodlands Grassland, chaparral, and desert scrub 15,000 years ago glacial periodAlpine tundra Spruce-fir forests Mixed conifer forest 0 km 2 km 3 km 1 km Elevation(km) PresentAlpine tundra Spruce-fir forests Mixed conifer forest Woodlands Grassland, chaparral, and desert scrub aspen oak, maple white birch sequoia result of competitionresult of competition
  8. 8. AP Biology At risk populations  Endangered species  limitations to range / habitat  places species at risk Socorro isopod Devil’s hole pupfish Iriomote cat Northern white rhinoceros New Guinea tree kangaroo Iiwi Hawaiian bird Catalina Island mahogany tree
  9. 9. AP Biology Population Spacing  Dispersal patterns within a population uniform random clumped Provides insight into the environmental associations & social interactions of individuals in population Provides insight into the environmental associations & social interactions of individuals in population
  10. 10. AP Biology Clumped Pattern (most common)
  11. 11. AP Biology Uniform Clumped patterns May result from direct interactions between individuals in the population → territoriality
  12. 12. AP Biology Population Size  Changes to population size  adding & removing individuals from a population  birth  death  immigration  emigration
  13. 13. AP Biology Population growth rates  Factors affecting population growth rate  sex ratio  how many females vs. males?  generation time  at what age do females reproduce?  age structure  how females at reproductive age in cohort?
  14. 14. AP Biology Life tableLife table Demography  Factors that affect growth & decline of populations  vital statistics & how they change over time Why do teenage boys pay high car insurance rates?Why do teenage boys pay high car insurance rates? females males What adaptations have led to this difference in male vs. female mortality?
  15. 15. AP Biology Survivorship curves  Graphic representation of life table Belding ground squirrel The relatively straight lines of the plots indicate relatively constant rates of death; however, males have a lower survival rate overall than females. The relatively straight lines of the plots indicate relatively constant rates of death; however, males have a lower survival rate overall than females.
  16. 16. AP Biology Age structure  Relative number of individuals of each age What do these data imply about population growth in these countries?
  17. 17. AP Biology Survivorship curves  Generalized strategies What do these graphs tell about survival & strategy of a species? What do these graphs tell about survival & strategy of a species? 0 25 1000 100 Human (type I) Hydra (type II) Oyster (type III) 10 1 50 Percent of maximum life span 10075 Survivalperthousand I. High death rate in post-reproductive years I. High death rate in post-reproductive years II. Constant mortality rate throughout life span II. Constant mortality rate throughout life span III. Very high early mortality but the few survivors then live long (stay reproductive) III. Very high early mortality but the few survivors then live long (stay reproductive)
  18. 18. AP Biology Trade-offs: survival vs. reproduction  The cost of reproduction  increase reproduction may decrease survival  age at first reproduction  investment per offspring  number of reproductive cycles per lifetime Natural selection favors a life history that maximizes lifetime reproductive success Natural selection favors a life history that maximizes lifetime reproductive success
  19. 19. AP Biology Parental survival Kestrel Falcons: The cost of larger broods to both male & female parents
  20. 20. AP Biology Reproductive strategies  K-selected  late reproduction  few offspring  invest a lot in raising offspring  primates  coconut  r-selected  early reproduction  many offspring  little parental care  insects  many plants K-selected r-selected
  21. 21. AP Biology Trade offs Number & size of offspring vs. Survival of offspring or parent Number & size of offspring vs. Survival of offspring or parent r-selected K-selected “Of course, long before you mature, most of you will be eaten.”
  22. 22. AP Biology Life strategies & survivorship curves 0 25 1000 100 Human (type I) Hydra (type II) Oyster (type III) 10 1 50 Percent of maximum life span 10075 Survivalperthousand K-selection r-selection
  23. 23. AP Biology Population growth change in population = births – deaths Exponential model (ideal conditions) dN = riN dt N = # of individuals r = rate of growth ri = intrinsic rate t = time d = rate of change growth increasing at constant rate intrinsic rate = maximum rate of growth every pair has 4 offspring every pair has 4 offspring every pair has 3 offspring every pair has 3 offspring
  24. 24. AP Biology African elephant protected from hunting Whooping crane coming back from near extinction Exponential growth rate  Characteristic of populations without limiting factors  introduced to a new environment or rebounding from a catastrophe
  25. 25. AP Biology Regulation of population size  Limiting factors  density dependent  competition: food, mates, nesting sites  predators, parasites, pathogens  density independent  abiotic factors  sunlight (energy)  temperature  rainfall swarming locusts marking territory = competition competition for nesting sites
  26. 26. AP Biology Introduced species  Non-native species  transplanted populations grow exponentially in new area  out-compete native species  loss of natural controls  lack of predators, parasites, competitors  reduce diversity  examples  African honeybee  gypsy moth  zebra mussel  purple loosestrife kudzu gypsy moth
  27. 27. AP Biology Zebra mussel ecological & economic damage ~2 months  reduces diversity  loss of food & nesting sites for animals  economic damage  reduces diversity  loss of food & nesting sites for animals  economic damage
  28. 28. AP Biology Purple loosestrife 19681968 19781978  reduces diversity  loss of food & nesting sites for animals  reduces diversity  loss of food & nesting sites for animals
  29. 29. AP Biology K = carrying capacity K = carrying capacity Logistic rate of growth  Can populations continue to grow exponentially? Of course not!Of course not! effect of natural controls effect of natural controls no natural controlsno natural controls What happens as N approaches K?
  30. 30. AP Biology 500 400 300 200 100 0 200 10 30 5040 60 Time (days) Numberofcladocerans (per200ml)  Maximum population size that environment can support with no degradation of habitat  varies with changes in resources Time (years) 1915 1925 1935 1945 10 8 6 4 2 0 Numberofbreedingmale furseals(thousands) Carrying capacity What’s going on with the plankton?
  31. 31. AP Biology Changes in Carrying Capacity  Population cycles  predator – prey interactions At what population level is the carrying capacity? KK KK
  32. 32. AP Biology Human population growth What factors have contributed to this exponential growth pattern? What factors have contributed to this exponential growth pattern? 1650→500 million 2005→6 billion Industrial Revolution Significant advances in medicine through science and technology Bubonic plague "Black Death" Population of… China: 1.3 billion India: 1.1 billion adding 82 million/year ~ 200,000 per day! adding 82 million/year ~ 200,000 per day! Doubling times 250m → 500m = y () 500m → 1b = y () 1b → 2b = 80y (1850–1930) 2b → 4b = 75y (1930–1975) Doubling times 250m → 500m = y () 500m → 1b = y () 1b → 2b = 80y (1850–1930) 2b → 4b = 75y (1930–1975) Is the human population reaching carrying capacity?
  33. 33. AP Biology Distribution of population growth 1 2 3 Time 19501900 2000 Developing countries 2050 4 5 6 7 8 9 10 11 0 Developed countries low fertility Worldpopulationinbillions World total medium fertility high fertility uneven distribution of population: 90% of births are in developing countries uneven distribution of population: 90% of births are in developing countries uneven distribution of resources: wealthiest 20% consumes ~90% of resources increasing gap between rich & poor uneven distribution of resources: wealthiest 20% consumes ~90% of resources increasing gap between rich & poor What is K for humans? 10-15 billion? There are choices as to which future path the world takes… There are choices as to which future path the world takes… the effect of income & education the effect of income & education
  34. 34. AP Biology Ecological Footprint 30.2 15.6 6.4 3.7 3.2 2.6 USA Germany Brazil Indonesia Nigeria India Amount of land required to support an individual at standard of living of population 20 4 6 8 1210 14 16 18 20 22 24 26 28 30 32 34 Acres uneven distribution: wealthiest 20% of world: 86% consumption of resources 53% of CO2 emissions uneven distribution: wealthiest 20% of world: 86% consumption of resources 53% of CO2 emissions over-population orover-population or over-consumption?over-consumption? over-population orover-population or over-consumption?over-consumption?
  35. 35. AP Biology Ecological Footprint Based on land & water area used to produce all resources each country consumes & to absorb all wastes it generates Based on land & water area used to produce all resources each country consumes & to absorb all wastes it generates deficit surplus
  36. 36. AP Biology 2007-2008 Any Questions?
  37. 37. AP Biology Difficult to count a moving target Measuring population density  How do we measure how many individuals in a population?  number of individuals in an area  mark & recapture methods sampling populations
  38. 38. AP Biology Evolutionary adaptations  Coping with environmental variation  regulators  endotherms  homeostasis  (“warm-blooded”)  conformers  ectotherms  (“cold-blooded”)
  39. 39. AP Biology Bright blue marble spinning in space Ecology
  40. 40. AP Biology biosphere ecosystem community population Studying organisms in their environment organism

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