BIO

• Relative dating


  Estimates whether an object is younger or older than other, but does not offer specific dates
• Absolute dating


  Provides more specific origin dates and time ranges
• Geologic time scale


  The "calendar" for events in Earth history, divided into eons, eras, periods, and epochs
• Phanerozoic eon


  • The last eon, started from 543 million years ago to present, divided into Paleozoic, Mesozoic, and Cenozoic eras
• Paleozoic era

  1. 542 mya to 251 mya

  2. Ordovician period (490 to 443 mya): Fungi, plants, and animals colonize land

  3. Silurian period (443 to 416 mya): First vascular plants appeared

  4. Devonian period (416 to 360 mya): Bony fishes diversified, insects and first amphibians appeared

  5. Carboniferous period (360 to 299 mya): First seed plants appear, origin of reptiles and amphibians dominate

  6. Permian period (299 to 251 mya): Reptiles diversify, major extinction of marine organisms

  
• Mesozoic era

  1. 248 mya to 65 mya

  2. Triassic period (251 to 200 mya): Dinosaurs evolve, origin of mammals, gymnosperms dominate

  3. Jurassic period (200 to 145 mya): Dinosaurs abundant, first birds appear, gymnosperms dominate

  4. Cretaceous period (145 to 65 mya): Angiosperms diversify, dinosaurs extinct at the end
• Cenozoic era

  Quaternary period (2.6 mya - Present): Pleistocene epoch - Ice ages and origin of Homo, Holocene epoch - end of last major glacial epoch, current time we are living in
• Mass extinction


  A short period of geological time in which a high percentage of biodiversity or distinct species dies out
• Major mass extinctions in Earth's history

  • Ordovician
  • Devonian
  • Permian
  • Triassic
  • Cretaceous
• Charles Robert Darwin


  Father of Evolution, born 1809, died 1882
• Fossil records


  • The most direct evidence of evolution, can document important transitions
• Transitional feature


  A fossil that shows an intermediate state between an ancestral trait and that of its later descendants
• Biogeography


  The study of how and why organisms live where they do, organisms share basic similarities because they evolved from a common ancestor
• Comparative anatomy


  An important tool that helps determine evolutionary relationships between organisms and whether they share common ancestors
• Homologous structure


  Similar physical features in organisms that share a common ancestor, but serve completely different functions
• Analogous structure


  Similar physical features and functions in organisms that do not share a common ancestor
• Embryonic development


  Organisms that are closely related may have physical similarities before they are even born

  
• Comparative embryology


  Reveals anatomical homologous not visible in adult organisms
• Vestigial structure


  Organs, tissues or cells in a body which are no longer functional as they were in their ancestral form
• Vestigial structures

  • Appendix
  • Wisdom teeth
  • Coccyx
• Evidence from molecular biology

  Molecular similarities provide evidence for the shared ancestry of life, DNA sequence comparisons can show how different species are related
• Central dogma


  Genetic information flows only in one direction, from DNA to RNA to protein, or RNA directly to protein
• Evolution


  Change in genetic frequency in a population
• Allele frequency


  The incidence of a gene variant in a population
• Population


  A group of individuals of the same species living and interbreeding within a given area
• Genotype


  The genetic makeup of an organism
• Phenotype


  The observable characteristics or traits of an organism
• Mechanisms of evolutionary change

  1. Mutation

  2. Gene flow

  3. Genetic drift

  4. Natural selection
• Mutation


  Any change or alteration that occurs during the process of DNA replication
• Gene flow


  Result of migrating individuals that breed in a new location, adding new alleles to the existing gene pool
• Genetic drift


  Change in frequency of an existing gene variant in a population due to random chance
• Natural selection

  When the environment changes, natural selection often favors different traits in a species
• Modes of natural selection


  • Stabilizing selection
  • Directional selection
  • Disruptive selection
• Artificial selection


  The same mechanism as natural selection, but controlled by human purpose rather than natural forces
• Hardy-Weinberg equilibrium


  A population has constant genetic stability if 5 criteria are met: random mating, large population size, no migration, no mutation, and no natural selection
• Binomial nomenclature


  The formal system of giving living things two names, combining the genus and species level

  
• Carolus Linnaeus


  The "Father of Taxonomy", studied identification, classification and naming of organisms
• Phylogenetic tree


  A diagram that represents evolutionary relationships among organisms, a hypothesis not a definitive fact

  
• Taxon (taxa)


  A group of organisms at any taxonomic rank, such as a family, genus, or species
• Sister taxa


  Taxa derived from a common ancestral node