Gen Biology 2

• Evolution


  The biological change of a species over a span of time
• Evolution


  • The process of evolution keeps a species alive and thriving
  • Allows organisms to successfully pass down their genes
• Dinosaur fossils are significant evidence of evolution and of past life on Earth

  
• The reason for dinosaur extinctions is unknown
• Planet Earth formed

  4.6 billion years ago
• Formation of Earth


  1. Dust left over from the birth of the sun clumped together to form planet Earth

  2. The other planets in our solar system were also formed in this way at about the same time
• Earth's Core and Crust formed

  4.5 billion years ago
• Formation of Earth's Core and Crust

  1. Dense metals sank to the center of the Earth and formed core

  2. The outside layer cooled and solidified to form the Earth's crust
• The Earth's first ocean formed

  4.4 billion years ago
• Formation of Earth's first ocean

  1. Water vapour was released into the Earth's atmosphere by volcanism

  2. It then cooled, fell back down as rain, and formed the Earth's first oceans

  3. Some water may also have been brought to Earth by comets and asteroids

  
• The first life appeared to the Earth

  3.8 to 3.5 billion years ago
• First life on Earth

  • Simple single-celled organisms
  • Exactly how life arose is a mystery
• Stromatolites

  Microbial reefs created by cyanobacteria (formerly known as blue-green algae)

  
• Clay Hypothesis


  • Proposed in 1985 by Graham Cairns-Smith
  • The first molecules of life might have met on clay, whose surface not only concentrated these organic compounds together, but also helped organize them into patterns
• Montmorillonite


  A type of clay
• Lamarck's Theory of Inheritance of Acquired Characteristics


  • If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring
  • Lamarck believed that giraffes stretched their necks to reach food, and their offspring and later generations inherited the resulting long necks
• Paleontology and Fossil Records


  • The study of the fossils and sedimentary rocks is the only way by which we can learn about past environments and climatic conditions on Earth and the ways by which life evolved and diversified
  • A fossil is the preserved remains of a dead organism from millions of years ago
  • Fossils can be formed from hard body parts, parts of organisms that have not decayed, or preserved traces of organisms

  
• 7 Hierarchy of Linnaeus

  Kingdom, Phylum Class Order Family Genus Species
• • According to it organisms are placed into taxonomic groups called Clades.

  • Based on the possession of Synapomorphic characters.

  • So organisms are classified based on the historical order of their evolutionary descent

  • It does not consider the phenotypic differences between the descendants of a common ancestor.

  • Cladistic taxonomy upholds the monophyletic origin of different groups from a common ancestor through Cladogenesis.
• • The original methods used in cladistic analysis and the school of taxonomy derived from the work of the German entomologist Willi Hennig, who referred to it as phylogenetic systematics.

  Father of Cladistics- Willi Hennig

  • What is now called the cladistic method appeared as early as 1901 with a work by Peter Chalmers Mitchell for birds and subsequently by Robert John Tillyard (for insects) in 1921.
• The term "clade" was introduced in 1958 by Julian Huxley.

  • Cladistic analysis by Willi Henning is to determine which character states are primitive and which are derived based on common ancestry Robert John Tilyard.