evolution

• Theory of evolution


  Theory postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations
• The theory of evolution is one of the fundamental keystones of modern biological theory. TRUE OF FALSE
• Charles Darwin's theory of evolution


  • Species evolve (or, as he put it, undergo "descent with modification"), and that all living things can trace their descent to a common ancestor
  • The idea is that species change over time, give rise to new species, and share a common ancestor
  • Suggested natural selection, in which heritable traits that help organisms survive and reproduce become more common in a population over time
• Charles Darwin's key observations


  • Traits are often heritable
  • More offspring are produced than can survive
  • Offspring vary in their heritable traits
• Charles Darwin's evolution through natural selection

  1. Natural selection depends on the environment

  2. Natural selection acts on existing heritable variation

  3. Heritable variation comes from random mutations
• Natural selection is the strongest force of evolution
• Mutation


  • Changes in the nucleotide sequence of DNA
  • Cause new genes and alleles to arise
  • Germ line mutations can be passed to offspring
  • Somatic mutations are not passed on
• Migration (gene flow)


  • Transfer of genes from the gene pool of one population to another
  • Increases genetic variability within population but tends to reduce differences between populations over time
• Genetic drift


  Describes how allele frequencies fluctuate randomly from one generation to the next
• Non-random mating


  • Organisms may prefer to mate with others of the same genotype or of different genotypes
  • Won't make allele frequencies change by itself, though it can alter genotype frequencies
• Recombination


  • Occurs when two molecules of DNA exchange pieces of their genetic material with each other
  • Happens during gamete formation
• Microevolution


  • The small-scale variation of allele frequencies in the gene of a species
  • Microevolutionary changes produce descendants that are in the same taxonomic group
• Macroevolution


  • The variation in allele frequencies at or above species level
  • Macroevolutionary changes occur due to an accumulation of microevolutionary changes
• Evidences of evolution


  • Fossil records
  • Comparative anatomy
  • Comparative embryology
  • Geographical distribution
  • Genetic data
  • Molecular biology
• Fossils are direct or indirect remnants of the past
• Fossil records show that many extinct organisms were different from those that exist today
• Similarity in the bones of different organisms suggests a common evolutionary origin
• Similarity in the early ages of growth of some representative organisms suggests a common ancestry among them
• Organisms that have similar characteristics may be found in different continents
• Similar organisms may inhabit different environments and evolve along separate lines
• Genetic data provide insight into the evolution of organisms, as they are used to present gene trees that provide a reconstruction of the common ancestors of organisms
• Similarities between biological molecules can reflect shared evolutionary ancestry
• All living organisms share the same genetic material (DNA), the same or highly similar genetic codes, the same basic process of gene expression, and the same molecular building blocks, such as amino acids