Evolution Lectures 10-14

• Von Baer's law


  The embryos of different species look similar in the early stages of development because of how general it is, then as they develop they start looking more distinct because of how specific they get
• Ontogeny


  Development of an organism
• Evolutionary development (evo-devo)

  The way that developmental processes have evolved and how these processes have led to the evolution of new structures that form life's diversity
• Homeotic genes


  Genes that determine the identity and position of anatomical structures during development
• Homeotic genes

  • Hox gene in animals. For fruit flies, if this gene is altered via mutation, the legs of the fly grow where an antenna is supposed to be
• Segmentation genes


  Genes that are associated with patterning of the body segments during development
• Segmentation genes


  • Present in humans, for example, the vertebral column which has different segments, cervical, thoracic, lumbar, and sacral
• Heterochrony


  The changes in rate and timing of development
• Heterochrony


  • The human skull develops rapidly compared to other primates, resulting in a shorter snout and larger braincase
• Recapitulation


  Appearance of traits in the juvenile stage of a descendent that were expressed in the adult stage of ancestral species
• Recapitulation


  • In early embryonic development, humans have gills, and over time they develop into other things like the jaw and ears. These gills humans have in the embryonic stage of life were present in our adult ancestors (fish)
• Acceleration


  Somatic traits appear earlier in development
• Hypermorphosis


  Traits appear later in development
• Paedomorphosis


  Appearance of traits in the juvenile stage of an ancestral species that are expressed during the adult stage of the descendent species
• Paedomorphosis


  • Axolotl retains its gills from the embryonic stage all the way through adulthood
• Progenesis


  Reproductive traits appearing earlier
• Progenesis


  • A species of beetles, they reach sexual maturation and reproductive capabilities in larvae, rather than in adulthood
• Neoteny


  Somatic traits appearing later in development
• Neoteny


  • Humans are born with large heads at birth, which carry out into adulthood. This is retained
• Hox genes (homeobox)


  Determines body structures from anterior to posterior
• Hox genes


  • In animals, not plants. Certain parts on the vertebrae link to different parts of the body (cervical = neck/head)
• Colinearity


  Organization of genes in which the position of a gene on a chromosome corresponds to the relative position of the body part that the gene regulates
• Colinearity


  • Certain parts on the vertebrae link to different parts of the body (cervical = neck/head) when developed
• Gene duplication


  Extra copy of a gene or set of genes
• Gene duplication


  • This can result in more complex body plans
• Paralogs


  A pair of genes within a genome that shares common ancestry due to gene duplication
• Paralogs


  • Alpha and beta-globin genes are paralogs because they arose from a common ancestor through gene duplication. They have similar functions but are regulated differently
• Nonfunctionalization


  The extra gene is lost, and everything stays the same
• Increased expression


  Expressed twice as much
• Subfunctionalization


  Only doing half the job
• Neofunctionalization


  Extra gene does something else
• Properties of life


  • Structural organization
  • Homeostasis
  • Metabolism
  • Growth
  • Reproduction
• Properties of life


  • Life cycle of a sunflower: Organization: composed of cells, tissues, organs. Homeostasis: regulate internal processes to maintain internal conditions. Metabolism: undergoes photosynthesis to make sunlight into glucose. Growth: start as a seed and grows into a plant. Reproduction: reproduce via seeds
• Habitable trinity model


  A concept that explains the conditions necessary for the emergency of life: 1. Water: provided medium for chemical reactions, 2. Energy: source needed to drive the chemical reactions (ex. sunlight), 3. Nutrients: chemical elements and compounds used as building blocks for biological molecules
• LUCA


  Last universal common ancestor; theoretical concepted based on molecular phylogenetics. Estimated to have lived about 3.8 billion years ago, which was a single celled organism. There is a lack of detail
• Miller's old vials


  Investigated the origin of organic molecules. His apparatus had a series of glass vials and tubes connected to represent the Earth's atmosphere, which contained gases that were supposedly present during early Earth. He then subjected this mixture to electrical sparks to simulate lightning. After a few days, he observed that organic compounds (amino acids) were observed in the vials
• Prebiotic chemistry


  Taking inorganic molecules and energy then making lipids, nucleotides, and amino acids. These molecules then make vesicles, RNA, and peptides, which overall contribute to the formation of a protocell
• Prebiotic soup


  The hypothesis suggests that the early Earth's oceans contained a mixture of simple chemicals. These chemicals have been constantly stirred by the heat of the Earth's interior, lighting, and UV. Over time, these conditions caused the chemicals to react and form complex molecules like amino acids
• Abiogenesis


  Formation of life from non-life precursor
• Alkaline vents


  Hydrothermal vents on the ocean floor release alkaline fluids rich in hydrogen and minerals. May have played a role in the origin of life on Earth because they provide a unique environment that could support prebiotic chemistry