gen bio Q4W6

• The objectives of this self-learning kit are to describe the evidence of evolution, explain the evolutionary relationships among organisms, and appreciate that evidences from paleontology, embryology, morphology, anatomy and molecular biology can be used to establish evolutionary relatedness
• Evolution


  The biological change process by which descendants come to differ from their ancestors
• Characteristics of living organisms

  • Cellular complexity
  • Growth and Development
  • Reproduction
  • Irritability/Ability to response to stimuli
  • Homeostasis
• Relative time


  Subdivisions of the Earth's geology in a specific order based upon relative age relationships (most commonly, vertical/stratigraphic position)
• Absolute time


  Numerical ages in "millions of years" or some other measurement, most commonly obtained via radiometric dating methods
• Types of evidence


  • Direct evidence
  • Indirect evidence
• Biogeography


  The study of the distribution of species on Earth in the past and present, and how the distribution is affected by abiotic factors such as habitat, climate and terrain
• The great diversification of the marsupials in Australia and the absence of other mammals reflects that island continent's long isolation
• Australia has an abundance of endemic species—species found nowhere else—which is typical of islands whose isolation by expanses of water prevents migration of species to other regions
• Alfred Russel Wallace: 'The Father of Biogeography'
• Fossil record


  Helps paleontologists, archaeologists, and geologists place important events and species in the appropriate geologic era, based on the Law of Superposition and radiocarbon dating
• Fossils provide solid evidence that organisms from the past are not the same as those found today; fossils show a progression of evolution
• The information obtained from fossils is relatively incomplete due to a small number of fossils found, rare preservation of soft tissues, destruction by erosion/earth's crust movement, and favorable fossilization conditions
• DNA and protein structure

  All living cells have the same basic DNA structure and use the same genetic code, and proteins produced from genes all come from the same set of amino acids
• Organisms that seem fairly similar on the basis of comparative anatomy, show more genes in common than organisms that aren't much alike
• Humans and chimpanzees have 96% of their genes identical, while humans and moths have 31 different positions on the amino acid chain
• Homology


  Similar biological structures or sequences in different taxa, implying divergent evolution from a common ancestor
• Homologous structures


  • Forelimbs of mammals (human, cat, whale, bat)
  • Front flippers of whales, wings of birds, running forelegs of dogs/deer/horses, short forelegs of frogs/lizards, grasping hands of primates
• Embryology


  The study of the development, structure, and function of embryos
• When comparing vertebrate embryos in the early stages of development, you will see striking similarities even in species that bear little resemblance in their adult form
• The human embryo passes through a stage in which it has gill structures like those of the fish from which all terrestrial animals evolved, and also has a tail that is usually reabsorbed before birth
• The development of mammals, fish, reptiles, and birds are linked to the branchial arteries
• Since natural selection occurs on the genetic variation that is presently available in a population, the "perfect" adaptation may not always occur, resulting in contrivances that are passed on through generations
• or if scientists prevent it from working) then the gills fail to develop. The development of mammals, fish, reptiles, and birds are linked to the branchial arteries.
• Biologists long ago proposed that fish evolved into amphibians, which evolved into reptiles, which evolved into birds. More recent studies of embryonic development support this idea.
• Comparing sections of DNA in difference species has shown that even organisms that seem to be different actually have large sections of identical DNA
• The layers of fossils in sedimentary rock shows the progression of organisms through time.
• Distribution - isolation islands have unusually high proportions of unusual species.
• Contrivances


  Characters that are passed on through generation will not be "perfectly" adapted based on evolutionary theory. Since natural selection occurs on the genetic variation that is presently available in a population, the "best" alternatives cannot constantly be found. Most of the time, existing traits are modified (contrived) to serve a new function.
• All living things evolved from a single common ancestor. There are certain key molecules and biochemical mechanisms shared by incredibly different organisms. For example, all organisms use DNA and/or RNA for their genetic code.
• Photosynthesis, cellular respiration, transcription, and translation are all identical or very similar in various types of organisms. When we look closer, we can see that there are many biochemical molecules which are identical in nearly all life forms.
• Cytochrome c


  A highly conserved protein that is a key component of the electron transport chain, which is a part of cellular respiration. Cytochrome c also has a function in many other reactions, including initiating programmed cell death.
• Hemoglobin


  A molecule used to transport oxygen
• Myoglobin


  A molecule used to store oxygen
• Trypsin


  A protease involved in the absorption of protein during digestion
• These shared biochemical molecules and pathways provide strong evidence for common descent and evolution.
• Charles Darwin was born in Shrewsbury, England


  1809
• In 1859, Darwin published his thoughts about evolution and natural selection in On the Origin of Species. It was as popular as it was controversial. The book convinced many people that species change over time—a lot of time—suggesting that the planet was much older than what was commonly believed at the time: six thousand years.
• Species distribution


  All the places where species live
• When looking closely at distributions, it is clear that many unique species occur in isolated pockets or islands. When looking at these unique species through the lens of evolution, we would expect unusual species in isolated areas because isolation is necessary before speciation can occur.