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CH 25 and 26 (terms (macroevolution (the broad pattern of evolution above…

- - - - Linnaeus’s binomial classification system gives organisms two-part names: a genus plus a specific epithet.
      - In the Linnaean system, species are grouped in increasingly broad taxa
        
        families in orders
        orders in classes
        classes in phyla
        phyla in kingdoms
        kingdoms in domains
      - Systematists depict evolutionary relationships as branching phylogenetic trees
        
        Many systematists propose that classification
        be based entirely on evolutionary relationships
        
        Unless branch lengths are proportional to time or genetic change,
        a phylogenetic tree indicates only patterns of descent
  - - - in comparison with organisms with very different structures and genetic sequences.
    - - distinguish molecular homologies from coincidental
        matches between taxa that diverged long ago.
  - - - such genes can diverge and potentially take on
        new functions.
    - - The small variation in gene number in organisms of varying complexity suggests that genes are versatile and may have multiple functions.
  - - - a method of estimating the date of past
        evolutionary events based on the amount of genetic change.
        
        Other DNA regions change in a less predictable way
  - - - consists of three great domains: Bacteria,
        Archaea, and Eukarya.
      - Phylogenies based in part on rRNA genes suggest that eukaryotes are most closely related to archaea
      - while data from some other
        genes suggest a closer relationship to bacteria
      - Genetic analyses indicate that extensive horizontal gene
        transfer has occurred throughout the evolutionary history of life
  - - - one that evolved in the lineage leading up to a clade and that sets members of that clade apart from other individuals
    - - The most likely tree
        is the one based on the most likely pattern of changes
- - - - The abiotic synthesis of small organic molecules
      - The joining of these small molecules into macromolecules
      - The packaging of these molecules into protocells
      - The origin of self-replicating molecules that eventually made inheritance possible
    - - formed 4.6 billion years ago, condensing from a
        vast cloud of dust and rocks that surrounded the young sun
        
        For its first few hundred million years, Earth was bombarded
        by huge chunks of rock and ice
      - This massive bombardment ended 4 billion years ago, setting
        the stage for the origin of life.
        
        The first atmosphere had little oxygen and was likely thick with water vapor
        
        along with compounds released by volcanic eruptions, such as nitrogen and its oxides, carbon dioxide, methane, ammonia, and hydrogen.
        
        As Earth cooled, the water vapor condensed into oceans, and much of the hydrogen escaped into space
      - 1920: Russian chemist A. I. Oparin and British scientist J. B. S. Haldane independently hypothesized that Earth’s early atmosphere was a reducing environment
        
        1953: Stanley Miller and Harold Urey, working at the
        University of Chicago, tested the Oparin-Haldane hypothesis
        
        yielded a variety of amino acids found in organisms today, along with other organic compounds.
        
        However, some evidence suggests that the early atmosphere was made up primarily of nitrogen and carbon dioxide and was neither reducing nor oxidizing
        
        Another hypothesis is that organic compounds were first
        produced in deep-sea hydrothermal vents,
        
        But alkaline vents have an environment that may have been more suitable for the origin of life
    - - The presence of small organic molecules, such as amino acids and nitrogenous bases, is not sufficient for the emergence of life as we know it
        
        2009 study the abiotic synthesis of RNA monomers, can occur spontaneously from simple precursor molecules
    - - The first genetic material was most likely RNA, not DNA
        
        RNA plays a central role in protein synthesis, but it can also function as an enzyme-like catalyst
        
        Such RNA catalysts are called ribozymes.
  - - - As a result, the fossil record is based primarily on the sequence in which fossils have accumulated in sedimentary rock layers, called strata
        
        The fossil record shows that there have been great changes
        in the kinds of organisms on Earth at different points in time
    - - One of the most common techniques is radiometric dating,
        
        In this process, a radioactive “parent” isotope decays to a “daughter” isotope at a characteristic rate
        
        The rate of decay is expressed by the half-life
        
        Each type of radioactive isotope has a characteristic half-life, which is not affected by temperature, pressure, or other environmental variables
    - - Some fossils provide a detailed look at the origin of new
        groups of organisms.
        
        the fossil record shows that the unique features of mammalian jaws and teeth evolved gradually over time, in a series of steps
        
        If all the known fossils in the sequence were arranged by shape and placed side by side, their features would blend smoothly from one group to the next.
        
        Some of these fossils would reflect
        how the features of a group that dominates life today
        
        Others would reveal side branches on the tree of
        life
  - - - As we’ve seen, the fossil record provides a sweeping overview
        of the history of life over geologic time.
        
        The First Single-Celled Organisms Stromatolites
        
        layered rocks that form when certain prokaryotes bind thin films of sediment together
        
        Stromatolites and other early prokaryotes were Earth’s sole inhabitants for about 1.5 billion years
        
        The First Eukaryotes
        
        Current evidence indicates that the eukaryotes
        originated by endosymbiosis
        
        when a prokaryotic cell engulfed a small cell that would evolve into an organelle found in all eukaryotes, the mitochondrion
        
        the serial endosymbiosis hypothesis supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
        
        Early Multicellular Eukaryotes
        
        The oldest known fossils of multicellular eukaryotes that can be resolved taxonomically are of relatively small red algae that lived 1.2 billion years ago
        
        The Cambrian Explosion
        
        Many present-day animal phyla appear suddenly in fossils formed 535–525 million years ago, early in the Cambrian period.
        
        Prior to the Cambrian explosion, all large animals were
        soft-bodied.
        
        The Colonization of Land
        
        larger forms of life, such as fungi, plants, and animals, did not begin to colonize land until about 500 million years ago.
        
        Plants appear to have colonized land in the company of
        fungi.
        
        these root fungi (or mycorrhizae),
        in turn, obtain their organic nutrients from the plants
        
        Arthropods were among the first animals to
        colonize land, roughly 450 million years ago.
        
        Tetrapods include humans,
        although we are late arrivals on the scene
        
        Photosynthesis and the Oxygen Revolution
        
        O2 being dissolved until it was able to react with other elements being dissolved as well such as iron
        
        iron oxide was being accumulated in sediments
        
        all of the dissolved iron had precipitated, additional O2 dissolved in the water until the seas and lakes became saturated with O2
        
        O2 finally began to “gas out” of the water and enter the atmosphere