Gen Bio 2

• Nicolas Steno


  Published the first laws of stratigraphy – the science of interpreting strata, or layers of rock, in Earth's outer surface

  
• Steno argued that the layers closer to the surface must be younger than the layers below them
• Giovanni Arduino


  Began naming the layers of rocks, organizing their layers based on their depth of composition
• Layers of rocks


  • Primary - crystalline rocks (igneous and metamorphic)
  • Secondary - layered rocks containing fossils (sedimentary)
  • Tertiary - gravel, sand, and clay beds (alluvium)

  
• William Smith


  Figured out that by comparing the remains of ancient organisms from different rock formations, he could match their ages no matter how far apart they were

  
• Smith made the first large scale geologic map showing the distribution and order of rock layers in Great Britain
• Geologic time scale


  A record of the life forms and geological events in Earth's history, developed by studying rock layers and fossils worldwide, with radioactive dating helping determine the absolute divisions

  
• Divisions of Geologic Time

  • Precambrian Time
  • Paleozoic Era
  • Mesozoic Era
  • Cenozoic Era

  
• Precambrian Time


  • Covers approximately 88% of Earth's history
  • Includes the Hadean, Archean, and Proterozoic eons
  • Major events: formation of Earth, observation of oldest rocks, formation of primitive fossils, generation of oxygen in primitive atmosphere, initialization of complex life

  
• Precambrian organisms


  • Soft-bodied creatures like worms and jellyfish, stromatolites and similar structures, traces of mats of algae-like microorganisms, and microfossils of other microorganisms
• Paleozoic Era


  • Explosion of life in the oceans began, most continents covered in warm, shallow seas
  • Invertebrates dominated, including trilobites
  • Fish emerged, leading to the arrival of amphibians
  • Early land plants including mosses, ferns and cone-bearing plants
  • Formed much of the limestone and coal deposits
• The Cambrian period is the 1st period of the Paleozoic Era, known as the "Age of the Trilobites"
• The Paleozoic era ended with the largest mass extinction in history, wiping out approximately 90% of all marine animal species and 70% of land animals
• Mesozoic Era


  • Began with the continents joined as Pangaea, which later broke up
  • Reptiles became the most abundant animals due to their ability to adapt to the drier climate
  • Dinosaurs were very active, with larger and more abundant dinosaurs appearing in the Jurassic Period
  • Small mammals and birds also appeared

  
• Mesozoic plants


  • Gymnosperms or plants that produce seeds, but no flowers, such as pine trees
  • Flowering plants appeared towards the end of this era
• The Mesozoic Era ended with a mass extinction event about 65 million years ago, causing the disappearance of many groups of animals including the dinosaurs
• However, not all forms of life died during this extinction event, and many animals you see today are descendants from the survivors
• Cenozoic Era


  • Began about 65 million years ago and continues today
  • Climate was warm and mild
  • Marine animals such as whales and dolphins evolved
  • Mammals began to increase and evolve adaptations to live in many environments
  • Grasses increased and provided food for grazing animals
  • Many mountain ranges formed, which may have helped cool the climate and led to Ice Ages
• Humans are thought to have appeared around 3.5 million years ago, during the most recent Quaternary Period of the Cenozoic Era

  
• Today we are in the Holocene Epoch of the Quaternary Period of the Cenozoic Era

  
• Systematics


  The scientific study and classification of organisms, aiming to understand their evolutionary relationships and create systematic arrangements such as phylogenetic trees to depict these relationships
• Evolution


  The gradual process of change in the inherited characteristics of populations over successive generations, driven by mechanisms such as natural selection, mutation, genetic drift, and gene flow, resulting in the diversity of life forms seen on Earth today
• People have classified the natural world for thousands of years based on traits such as edibility, cultural meaning, and utility
• Naturalistic Systematics


  Around the 18th century, naturalists sought to classify nature in a way that reflected nature, rather than the way humans use nature
• Linnaeus


  In 1735, Carl von Linnae ("Linnaeus") published Systema Naturae, a new approach to classifying nature that used nested hierarchies. Today's system is grounded in this method
• Binomial nomenclature


  Linnaeus published a system of binomial nomenclature, still in use today
• Species Plantarum


  Linnaeus published Species Plantarum, describing and classifying known organisms
• Linnaeus' Three Kingdoms of nature

  • Plants
  • Animals
  • Minerals
• 2 Kingdom system

  Linnaeus divided all living things into two kingdoms: Plants and Animals
• Up until the 1960's, textbooks used the 2 Kingdom System to describe the living world
• Many one-celled organisms, such as Euglena, don't fit well in a 2 Kingdom system
• Analogous structures are solutions to a common challenge, while homologous structures are inherited similarities
• Whittaker developed first a 3-kingdom system (Fungi, Plants, Animals) and later a 5-kingdom system
• Domains


  A new taxonomic level added above Kingdoms: Bacteria, Archaea, Eukarya
• Domains


  • Bacteria
  • Archaea
  • Eukarya
• Humans are classified as Domain: Eukarya, Kingdom: Animalia, Phylum: Chordata, Class: Mammalia, Order: Primates, Family: Hominidae, Genus: Homo, Species: Sapiens
• Evolutionary forces

  • Natural selection
  • Mutation
  • Genetic drift
  • Gene flow
• Natural selection


  The process where organisms with advantageous traits are more likely to survive and reproduce
• Causes of natural selection: Environmental pressures, competition for resources, and predator-prey interactions
• Mutation


  Random changes in an organism's DNA sequence, introducing new genetic variation