Exploring Life Quiz 4.1

• Evolution


  • The change over time
  • The process by which modern organisms have descended from ancient organisms
• Scientific theory


  A well-supported testable explanation of phenomena that have occurred in the natural world
• Voyage of the Beagle


  February 12th, 1831
• Voyage of the Beagle

  • Charles Darwin (captain)
  • H.M.S. Beagle (ship)
  • Voyage around the world (destination)
  • Evidence to propose a revolutionary hypothesis about how life changes over time (findings)
• Argentina and Australia had similar grassland ecosystems but were inhabited by very different animals, and neither country was home to the sort of animals that lived in European grasslands
• Darwin posed challenging questions about why there were no rabbits in Australia, despite the presence of habitats that seemed perfect for them, and why there were no kangaroos in England
• Darwin collected fossils, some of which resembled organisms still alive today while others looked unlike any creature he had ever seen, leading to new questions about why so many species had disappeared and how they were related to living species
• The Galapagos Islands


  1. Smallest, lowest islands were hot, dry, and nearly barren

  2. Higher islands had more rainfall and different plants and animals

  3. He was fascinated by the land tortoises and marine iguanas, which varied from one island to another
• Darwin observed that the characteristics of plants and animals varied among the Galapagos Islands
• James Hutton's Theory of geological change

  • Forces change Earth's surface shape
  • Changes are slow
  • Earth much older than thousands of years
• Charles Lyell's "Principles of Geography"


  • Geographical features can be built up or torn down
  • Darwin thought if Earth changed over time, what about life?
• Lamarck's Theory of Evolution


  • Theory of Tendency toward perfection (e.g. giraffe necks)
  • Theory of Use and Disuse
  • Theory of Inheritance of Acquired Traits
• Thomas Malthus' theory on Population Growth


  • If population grew, there would be insufficient living space and food would run out
  • Darwin applied this theory to animals
• Russel Wallace wrote an essay summarizing evolutionary change from his field work in Malaysia, which gave Darwin the drive to publish his findings
• Natural Selection


  The process by which organisms best adapted to their environment survive and reproduce, leading to changes in inherited traits over time
• Natural variation


  • Differences among individuals of a species
• Artificial selection


  Nature provides variation among organisms, and humans select what they find useful
• Evolution by Natural Selection


  1. The Struggle for Existence (members of each species have to compete for food, shelter, other life necessities)

  2. Survival of the Fittest (some individuals are better suited for the environment)

  3. Natural Selection (over time, natural selection results in changes in inherited traits that increase a species' fitness in its environment)
• Descent with Modification


  Each living organism has descended, with changes, from other species over time
• Common Descent


  Organisms were derived from common ancestors
• Darwin's Evidences of Evolution


  • The Fossil Record (each layer shows change)
  • Geographic Distribution of Living Things (similar environments have similar types of organisms)
  • Homologous Body Structures (Comparative Anatomy) (different mature forms in different organisms, but develop from same embryonic tissue; same structure, different function; vestigial organs)
  • Similarities in Early Development (Comparative Embryology) (all living things' embryos look the same)
• Summary of Darwin's Theory

  • Individuals in nature differ from one another (Genetic variation)
  • Organisms produce more offspring than can survive, many of those who do not survive do not reproduce (Population growth)
  • Because more organisms are produced than can survive, each species must struggle for resources (The struggle for existence)
  • Each organism is unique, each has advantages and disadvantages in the struggle for existence (Natural selection)
  • Individuals best suited for the environment survive and reproduce most successfully (Survival of the fittest)
  • Species change over time (Adaptation)
  • Species alive today descended with modification from species that lived in the past (Descent with modification)
  • All organisms on Earth are united into a single family tree of life by common descent (Principle of common descent)
• Charles Darwin


  • An English naturalist
  • Traveled around the world on his ship, the Beagle
  • Studied species and fossils in the Galapagos Islands and around the world
  • Wondered why some species survived while others became extinct
  • Proposed the theory of natural selection
  • Published "The Origin of Species" in 1859
• Organisms change over time, the ones living today are different from those that lived in the past, and many organisms have gone extinct
• Change occurs slowly from generation to generation, supported by the fossil record, with no naturalist observing the sudden appearance of new species
• All organisms come from a common ancestor, with populations splitting into different species over time, and any pair of organisms having a common ancestor, which explains the similarities of organisms classified together and why similar species tend to occur in the same geographic region
• Natural Selection


  "I have called this principle, by which each slight variation, if useful, is preserved, by the term of natural selection."
• On the Galapagos Islands, Darwin studied mockingbirds, finches, and tortoise shells, finding variations between the different islands, as well as fossils of extinct animals
• Darwin's finches provide an example of how these finches adapted to their environment to survive through natural selection, with variations in their beak shapes
• The peppered moth example shows how changes in the environment can lead to changes in the prevalence of different color variations in a population through natural selection
• Many animals have evolved to resemble their environment through camouflage, which increases their chance of survival by making it difficult for predators to find them
• Darwin believed that natural selection leads to the formation of new species, sometimes with many species evolving from a single ancestral species, as seen in the similarities of Hawaiian honeycreepers, which is an example of adaptive radiation
• thus, there were more dark moths than light moths
• Camouflage


  • Many animals evolved to resemble the environment around them
  • This makes it difficult for predators to find them
  • This also makes it easier for predators to sneak on prey
• Adaptive radiation


  An evolutionary pattern in which many related species evolved from a single ancestral species
• Divergent evolution


  Two or more related species becoming more and more dissimilar
• Divergent evolution


  • red fox and kit fox
  • Red fox lives in mixed farmlands and forests, its red color helps it blend with trees
  • Kit fox lives on the plains and deserts, its sandy color helps conceal itself from prey and predators, its large ears are an adaptation to the desert environment
• Convergent evolution


  Opposite of divergent evolution, unrelated species become more similar in appearance as they adapt to the same kind of environment
• Convergent evolution


  • frogs and chameleons, they have both developed harpoon-like tongues to catch insects
• Co-evolution


  The joint change of two or more species in close interaction