Learning Objectives

1
Learning Objectives

• To understand
• I. the history of our planet
• Non-living periods
• Periods with life
• II. that the Earth and the diversity of life
  has changed over time
• III. trends in diversity over time

2
Early Earth

• Earth began forming 4.5 bya
• Evidence
• 1st atmosphere N2, H2, CO and CO2
• no O2 or ozone, high UV winds
• H2O was present

3

• Experiments mimicking conditions on early earth
  demonstrate that organic compounds can form from
  inorganic compounds
• Amino acids, nucleotides, carbs, ATP, NAD(P)
• Phospholipid bubbles provide structure for a
  cell

4
First Life

• Prokaryotes originated 3.8 bya in Archean
  proliferated through Proterozoic
• Chemoautotrophs made carbohydrates using
  chemicals in environment - non-oxygen releasing
  released sulfur
• Oxygen releasing photosyn. arose later
  (photoautotrophs)
• Breakdown of carbohydrates to ATP did not req
  oxygen at first (fermentation), but later
  organisms use O2

5

• Photosynthesis 3.2 bya
• Effects of oxygen
• Mass extinction of many organisms
• Prokaryotic diversity of a different kind starts
  to diversify
• ozone layer develops 2 bya

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Origin of eukaryotic cells

• 1 bya
• Endosymbiosis
• partnerships between prokaryotic ancestors
• chloroplasts and mitochondria
• Evidence?

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youngest
oldest

• Archean
• prokarys. only
• Proterozoic
• Paleozoic
• Mesozoic
• Cenozoic

youngest
oldest
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Paleozoic

• Started with mass extinction, then adaptive
  radiation of multicellular organisms
• Life proliferated in seas
• Cambrian explosion of inverts
• Armored fish follow
• Then land invasion plants,
• insects, amphibians

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Mesozoic

• Adaptive radiation of seed
• bearing plants and reptiles
• followed by mass extinction

10
Cenozoic

• Adaptive radiation of mammals
• H. sapiens evolved in last 40,000 yrs.
  Agriculture arose 10,000 yrs.
• Average extinction rates
  
• 1 spp./1 million spp./year
• 20th century extinction rates
• 1,000 -10,000 spp. / 1 million spp. / year

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Biodiversity

• Millions of species now on earth (2 million)
• Diversity has changed radically over time
• Observations - Many species look like other
  species
• Broad similarities lineages with similar
  phenotypes life histories
• Reptiles snakes, lizards, crocs
• Gymnosperms pines, spruce, fir, larch
• Primates great apes, chimps, humans
• Within a very closely related group, the
  different species of the group tend to live in
  different habitats
• White Pine and Jack Pine and tamarack live in
  different habitats
• Great apes (baboons, gorillas, orangutans) live
  in different habitats

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Conclusions

• Broad similarities in life histories are present
  because lineages are related
• Supported by initially by studies of anatomy,
  development, and now by molecular data
• Similar species in different habitats exist b/c
  each habitat selects for traits in slightly
  different ways

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• Taxonomy classifies organisms to reflect
  relatedness.
• Taxon - a group of organisms with similar form(s)
  that are related.
• Reptiles are a taxonomic group
• Gymnosperms are a taxonomic group
• Then, all of the pines (white, red, limber,
  lodgepole, etc) are another more specific
  taxonomic group. All pines are closely related.

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Classification system

• developed by Linnaeus (1758)
• hierarchial organization
• binomial species name
• genus and epithet species
• Used to identify organisms

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• Species belong to a genus (1st part of name)
• Genera grouped into families
• Families grouped into orders
• Orders -- classes
• Classes -- Phyla
• Phyla
• Kingdoms 6 kingdoms
• Domains are the largest unit
• Eukarya, Bacteria, Archaea

Domain
Eukarya