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Bio1020, Diversity of Life: February 3.docx

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University of Lethbridge
BIOL 1020
Robert Laird

February 3, 2014 – Biology History of life on earth: Chapter 25 • Earth is 4-5 billion years old • The decay of the isotopes in surrounding sediments provides a signal of approximate age • Alberta Ammonite fossile: ammonite is complete extinct. • History is presented is linear, • Paleontology: looks at the history of life on earth. Royal Terrell Museum shows fossils mostly found in Alberta. • What do fossil tell us about life? What led to extinction? How old is it? o Magnitude of change has been enormous o Extinction is a common feature (99% of all organisms?) o Pace of evolution and natural selection • How can we estimate ‘age’ : decay of isotopes on sediments o Radiometric dating of sediment (not fossils), nitrogen, carbon • Macroevolution: pattern of evolution above the species level, over very long time periods o Origin of prokaryotes (not long after the creation of the solar system) o Origin of eukaryotes, natural selection favors a nucleus. o Origin of multicellularity the constraints of having one cell led to multicell o Origin of animals o Origins of other taxa o Mass extinctions (5 or 6 of them) are we currently in a 6 mass extinction event? o Figure 25.1: geologic record. be familiar with it, general aware of the length of it (4-5 billion years) o Figure 25.7 is very important! Geological clock, must know the key words Hypothesis for the origin of life • Book supports one hypothesis • The nature of indirect evidence (will be able to understand more about the origin if we can find another planet with life on earth) • When and how did first cells (and their precursors) appear? • Chemical processes + physical processes + natural selection = life o What is life?  Developing  Metabolizing energy (using energy for its own needs)  Homeostasis  Reproducing • Propose 4-stage process: ultimately leads to potential life o 1. Synthesis of organic compounds creating something more complicated  Earth’s early atmosphere • Water vapor • Nitrogen, CO 2 Methane, Ammonia o Miller-Urey experiments (1953) Figure 4 (Chapter 4)  Hypothesis:
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