DIVERSITY OF LIFE OVER TIME

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DIVERSITY OF LIFE OVER TIME
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DIVERSITY OF LIFE OVER TIME

• Shrub versus Arrow Metaphor
• Radiation and increases in diversity
• Extinction events and decreases in diversity

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DIVERSITY OF LIFE OVER TIMEComplicated Causes of
Extinction

• Species
• Groups of species
• Entire ways of living
• Extraterrestrial to anthropogenic
• Populations of that species or group of species
  no longer exist

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DIVERSITY OF LIFE OVER TIMEEndangered Species

• Species found only in a restricted geographic
  region and vulnerable to extinction
• Rate of extinction increasing. Why?
• Human population
• 9 billion in 2050.
• Resource Demands?

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ECOLOGICAL THEATER
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Question of the Day

• China has a one child policy- A woman can have
  only one child if she lives in the city and two
  children if she lives in the country. If she
  violates this policy, she is fined.
• WHY do you think they have that policy?
• Do you think that is a good idea, bad idea, fair,
  etc.?

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ECOLOGICAL THEATER

• Population Ecology
• Population All individuals of the same species
  that occupy a specified area
• Community Ecology
• Community All populations in a habitat. Group
  of organisms with similar life-styles
• Ecosystem Ecology
• Array of organisms, together with their
  environment, interacting through a flow of energy
  and a cycling of materials

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ECOLOGICAL THEATERPopulation Ecology
Individual Monarch Butterfly (Dannaus plexippus)
1. Complete metamorphosis 2. Lay eggs on milkweed
plants 3. Distasteful to predators 4. Long
distance migration
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ECOLOGICAL THEATERPopulation Ecology
Monarch Butterfly (Dannaus plexippus)
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ECOLOGICAL THEATERPopulation Ecology
Cellular/Tissue Scale
Molecular Scale
Organismal Scale
Population/Community Scale
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POPULATION ECOLOGYCharacteristics of Populations

• Definition Group of individuals of same species
  Occupying given area
• Gene pool all genotypes in the population basis
  for morphological, physiological and behavioral
  traits
• Demographics vital statistics

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POPULATION ECOLOGYDemographics

• Population Size Number of individuals that
  contribute to a populations gene pool
• Age Structure Number of individuals in each of
  several age categories.

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POPULATION ECOLOGYAge Structure

• Pre-reproductive
• Reproductive
• Post-reproductive

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POPULATION ECOLOGYDemographics

• Population Density Number of individuals in some
  specified area or volume of habitat type of
  place where a species normally lives.
• Population Distribution General pattern in which
  individuals are dispersed in a specified area

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POPULATION ECOLOGYDistribution in Space
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POPULATION ECOLOGYPopulation Size and Growth

• Natality Births
• Mortality Deaths
• Immigration Individuals from other populations of
  same species join population
• Emigration Individuals leave population
• Population Growth rate? See textbook

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POPULATION ECOLOGYPopulation Size and Growth

• Calculate growth?
• Population growth rate
• (births immigration) - (deaths emigration)
• Population growth rate
• (births/individual - deaths/individual) X number
  of individuals in population
• Change in population size r N

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Population Size and GrowthPatterns of
Reproduction

• Average number of offspring produced each time
• Age at which organism first reproduces
• Frequency with which each organism reproduces
• Length of organisms reproductive life span
  

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How Do Populations Grow?

• Some species produce fewer but longer-lived
  offspring.
• The golden eagle is a long-lived, rather slowly
  reproducing species.

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How Do Populations Grow?

• Other species produce large numbers of offspring
  quickly. Examples?
• The growth rate is so great that, unchecked, the
  offspring of one bacterium could produce a layer
  around the Earth 7 feet deep in 48 hours.
• Because this does not happen, many bacteria must
  die.
• Recall 5 facts and 3 inferences to explain natura
  selection.

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How Do Populations Grow?
time(minutes)
number ofbacteria
bacteria
020406080 100120140160180 200220
12481632641282565121,0242,048
1,200 1,100 1,000 900 800 700 600 500 400 300 200
100 0
number of individuals
Exponentialgrowth curvesare J-shaped
0
60
120
180
240
time (minutes)
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POPULATION ECOLOGYPopulation Growth
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POPULATION ECOLOGYPopulation Size and Growth
Human Population
Consequences?
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POPULATION ECOLOGYPopulation Size and Growth

• Limits on Population Growth?
• Carrying Capacity
• Population growth rate
• net rate of reproduction per individual
• X number of individuals X portion of
  unexploited resources

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POPULATION ECOLOGYPopulation Growth
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POPULATION ECOLOGYPopulation Size and Growth
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POPULATION ECOLOGYPopulation GrowthLimitations

• Availability of space Crowding
• Availability of food
• Disease
• Predation

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POPULATION ECOLOGYPopulation Consequences
Human Population
Consequences?
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POPULATION ECOLOGYPopulation Growth Consequences
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Carrying Capacity

• Earths Carrying Capacity has been
• estimated between 3 billion to 44 billion, based
  on resource use per person
• There will be an estimated 7 billion people on
  Earth by 2010.
• Scientists suggest that it takes 5.6 acres of
  land to support one human (on average). But
• There is only enough resources on Earth now for
  4.7 acres a person
• If all people on Earth lived as Americans do, we
  would need 5.4 Earths to supply demands

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POPULATION ECOLOGYPopulation Growth Consequences