Evolution

• Geologic Time Scale - refers to Earth's record of appearances of life forms.
• Precambrian (4B years ago) - represents the period of the birth of planet and appearance of life forms.
• Phanerozoic (542 million years ago) - 'visible life on earth' constructed through rock units.
• Precambrian eras - Proterozoic, Hadean, Archean
• Paleozoic - age of invertebrates

  • silurian
  • devonian
  • carboniferous
  • ordovician
  • permian
  • cambrian
• Mesozoic - age of reptiles

  • triassic - first mammal and dinosaurs
  • jurassic - diversity of dinosaurs
  • cretaceous - dinosaurs extinction
• Cenozoic - age of mammals

  • tertiary - mammal diversity
  • quaternary - human evolution
• Epoch - shortest subdivision unit of the geologic time scale
• Evolution - cumulative genetic changes in population of organisms over time; acts on a population.
• Population - group of interbreeding organisms of the same species.
• It is the genetic changes in populations that are passed on to successive generation over time.
• Antibiotic resistance is a startling example of evolution.
• Natural selection attempted to explain the cause of evolutionary changes among organisms.
• Fitness refers to adaptive traits of the individual that makes it likely to survive and reproduce.
• Overproduction - every species tend to produce more individuals than can survive to maturity.
• Variation - the individuals of a population have many charateristics that differ.
• Selection - there are individuals that can survive longer and reproduce more than others
• Adaptation - traits of those that survive and reproduce becoe more common in a population.
• Directional selection - favors one phenotype over another.
• Stabilizing Selection - favors intermediate phenotypes
• Disruptive selection - favors extreme phenotypes.
• Artificial selection - process of selecting plant or animal individuals for breeding
• Artificial selection is the primary principle behind selective breeding for producing new varieties of plants. Through selective breeding, there is an increase in chances of achieving desirable traits.
• Aristotle (350BCE) - individuals in species are basically identical and can be arranged hierarchically, and species remain the same.
• Buffon (AD1749) - species migrate and change from their original location to a new environment.
• Erasmus Darwin (1794) - life evolved from one common ancestor
• Lamarck (1809) - new species evolve from existing ones through environmental forces acting on them.
• Lyell (1830) - all changes in nature are gradual and uniform.
• Darwin and Wallace - NATURAL SELECTION
• Aristotle's Historia Animalium classifies organisms based on structure and function.
• Aristotle's Scala Naturae organized organisms hierarchically, which humans are on top of the ladder.
• Comte de Buffon his work, The Natural History of Animals, put forth ideas in comparative anatomy
• Use and disuse by Lamarck

  1. Changes in organisms - simpler forms of life are continuously formed through spontaneous generation.
  2. Inheritance - traits that the organisms acquired through change can be passed on to their offspring.
• Alfred Russell Wallace - traveled to South America to collect plant and animal specimens. Similar to Darwin, he also devised a theory by natural selection to support what he saw on the voyage.
• Charles Darwin is the father of evolution.
• The HMS beagle - the beagle had 3 major voyage; Charles Darwin joined the second voyage.
• Galapagos finches - Darwin concluded that the shape and size of their beaks were closely related to the type of food they consume.
• Common Descent - all species have common ancestry
• Gradualism - the changes that happens in organisms does so for very long periods of time.
• Speciation - organisms change and evolve to form distinct new species.