evidence

• fossils


  remains, impressions or traces of life forms that have been preserved in materials such as ice, sediment or amber
• relative dating


  qualitative method of dating that focuses on the description rather than the numerical age of the fossils
• law of superposition


  each rock layer is older than the layer above it
• stratigraphy


  a process involving the comparison of the position of rock strata (layers) that contain fossils to determine the comparative time scale of their occurrence
• index fossils


  fossils that existed during limited periods of time that can be used as guides to determine the relative age of rocks in which they are preserved
• absolute dating


  quantitative method of dating which provides a fossil's specific numerical age
• radiometric dating


  the process of determining the age of rocks or fossils from the decay of radioisotopes - unstable atoms that are taken up by rocks or living matter in proportions equal to the environment - once an organism dies, its radioisotope level decreases
• comparative genomics


  genomics: the study of genomes - the genetic material within an organism

  comparative genomics: identifying similarities and differences between the genomes of different organisms

  scientists are able to sequence genomes using specialised computers to analyse a sample of DNA and reveal the order of the bases
• DNA sequencing


  the order of nitrogenous bases (adenine (A), guanine (G), cytosine (C) and thymine(T)) in DNA codes for proteins and determines what an organism looks like

  once the DNA is sequenced it can be compared to another sequenced genome

  mitochondrial DNA (mtDNA) can also being used to date genetic events - used to estimate when the organisms shared a common ancestor
• phylogenetic trees


  used to track the evolutionary relationship of different species
• comparative embryology


  embryology: study of embryos - unborn or unhatched offspring in the early stage of their development

  comparative embryology: identifying similarities and differences between the embryos of different organisms
• homologous structures


  similar features found in different species that have been inherited from a common ancestor

  eg. all mammals share the same arrangement of bones in their forelimbs (humerus, ulna, radius, carpals, metacarpals, phalanges)
• analogous structures


  similar features found in different species that evolved independently - the features were NOT inherited

  eg. dolphins and sharks share similar features but are not related
• biogeography


  the study of geographical distribution of organisms

  regions that separated from the rest of the world a longer time ago, eg. Australia, often have distinctive, unique organisms
• cane toads - info


  introduced to Qld from Hawaii in 1935 to reduce levels of cane beetles which were destroying sugarcane crops

  the toads were not able to reduce cane beetle levels as they were not able to reach the beetles

  ended up eating many native insects and poisoning the native animals which attempted to eat them
• cane toads - evolutions

  it was advantageous to spread out to ensure a female toad didn't eat another female's eggs

  the toads that could move more quickly were able to move further away from the population and avoid their offspring from being eaten - they would encounter more toads with similar fast characteristics, increasing the population of toads with the same characteristics and were able to spread quickly

  these toads, frontier toads, had notable adaptations from the original cane toads - they are larger, their legs are 10% longer and stronger and they move 10 times as far in a day
• antibiotic-resistant bacteria


  the gene that allows bacteria antibiotic resistance is random through mutation

  this mutation allows for a higher chance of survival, therefore more reproduction, therefore more bacteria with the same mutated gene

  eg. penicillin (which inhibits the enzyme which catalyses the last step in bacterial cell wall synthesis) - some bacteria have developed pumps to remove it once it enters, some use an alternative enzyme to make their cell wall, some have adjusted the original enzyme so penicillin cannot block it