Origins of Biological Diversity

1
Origins of Biological Diversity

• Chapter 15

2
Fossil Record

• Found in sedimentary rock
• Show clear relationship for many species over
  time example horse
• Two methods of dating
• 1. Relative Dating
• 2. Radioactive Dating

3
Relative Dating

• Determine age of fossils relative to other
  fossils in different layers of rock
• Rock superposition- younger rock on top of older
  rock
• Index fossils- fossils which we know when they
  lived

determines relative age
4
Radioactive Dating

• Elements such as 14C decay/breakdown at steady
  rate into another element
• half life- length of time for half the
  radioactive atoms in sample to decay
• of radioactive atoms in bodies constant through
  time
• Example carbon-14 decays to nitrogen-14, half
  life 5,730 years
• Uranium-238 decays into Lead-206, 4.5 billion
  years

Determine actual age
5
Geologic Time Scale

• Based on relative and radioactive dating
• Displays evolution of life and geologic events
• Divided into eras
• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic
• Eras divided into periods, periods into epochs

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Precambrian Era

• 4.6 bya to 580 mya
• 1st prokaryotic cell
• Stromatolites- mats of photosynthetic bacteria
• 1st eukaryotic cell
• 87 of Earths history

7
Paleozoic Era

• 579 mya to 245 mya
• Age of the Invertebrates (marine)
• Jawless Fish then Jawed (1st vertebrates)
• First forests (coal forming)
• Amphibians and reptiles
• Pangea exists

Agnaths
8
Mesozoic Era

• 244 mya to 65 mya
• Triassic- Age of the Reptiles, mammal appear
• Jurassic- dinosaurs flourish
• Cretaceous- first flowering plants, mass
  extinction climate change
• 135 mya Pangea splits into Laurasia and Gondwana

9
Cenzoic Era

• 64 mya to present
• Age of the Mammals
• Primates evolve
• Modern humans 200,000 years ago
• Plate tectonics, present day positions

10
Comparative Embryology

• Similar developmental stages in vertebrate
  embryos
• Example, gill pouches and bony tails

11
Comparative Anatomy
VESTIGIAL STRUCTURES
HOMOLOGOUS STRUCTURES
12
Comparative Biochemistry

• Same four bases in DNA
• Same 20 amino acids
• Produce similar proteins (order of amino acids)
• Example, humans DNA 98.2 similar to chimpanzee
• Example, Cytachrome C 104 aas, same in human and
  chimp, dog 13 differences, rattlesnakes 20
• Populations evolve, individuals do not