Evolution Theories and Origin of Life Quiz

Myiasis

• Invasion of tissue by fly larvae (maggots)
• Feeding on living or dead tissue
• Facultative myiasis: maggots develop in foul-smelling wounds (especially pus-producing wounds)
• Maggot therapy: live (disinfected) maggots introduced into non-healing wounds to clean out necrotic tissue (debridement)

History of Earth

• Archaen → Proterozoic → Phanerozoic → Cenozoic
• 13.8 billion years ago - Big Bang
• 4.6 billion years ago - Start of solar system
• 4.55 billion years ago - Origin of Earth
• 4 to 3.5 billion years ago - Origins of life (cooling of Earth, formation of crust and oceans)

What is Life?

• DNA, cells, metabolism, adaptation, homeostasis, growth, reproduction and evolution.
• Metabolism:
  • Absorption of nutrients.
  • Excretion of wastes.
  • Energy acquisition and transformation (e.g., Krebs cycle).
  • Cellular synthesis.
• Reproduction:
  • Growth: duplication of all cellular components.
  • Division of discrete units (cells).
• Evolution:
  • Variation, reproduction, mutation
  • Mutation: mistakes in copying cell components

Origins of Life: Stages 1-4

• Stage 1: Organic molecules (nucleotides and amino acids) produced prior to cells.
• Stage 2: Nucleotides and amino acids polymerized to form DNA, RNA and proteins.
• Stage 3: Polymers enclosed in membranes.
• Stage 4: Polymers enclosed in membranes acquire cellular properties.

Origin of Organic Molecules

• Reducing Atmosphere Hypothesis: Early Earth atmosphere conditions and electrical discharge produced organic compounds.
• Extraterrestrial Hypothesis: Organic compounds delivered to Earth by meteorites.
• Deep Sea Vent Hypothesis: Organic compounds formed in the temperature gradient between extremely hot vent water and cold ocean water.

Stage 2: Organic Polymers

• Experimentally, prebiotic synthesis of polymers (nucleic acids and polypeptides) occurs on clay surfaces. Hydrolysis competes with polymerization in solution.

Stage 3: Formation of Boundaries

• Protobionts (precursors to living cells) form boundaries – aggregate of molecules/macromolecules that maintain an internal chemical environment distinct from the surroundings using lipid bilayers.

RNA World

• RNA is a first macromolecule in protobionts.
• RNA functions in storing information, self-replication and enzyme function.
• Advantages of DNA, RNA, protein world: information storage (DNA), metabolism (proteins).

Origins of Life Summary

• Formation/accumulation of organic molecules.
• Polymerization of nucleic acids & proteins.
• Formation of protobionts
• Synthesis of cell components by ribozymes
• Synthesis of proteins by DNA, RNA, & ribosomes
• Replication of DNA

Fossils and Types of Rock

• Sedimentary rocks contain fossils.
• Igneous rocks are used to date rock layers.
• Radioactive isotopes in rocks allow dating rocks and measure extinct time.

Changes in Living Organisms

• Changes in climate, atmosphere, landmasses, floods etc.
• Living organisms can adapt to changes and allow for new types of organisms.
• Responsible for many extinctions.

Time Periods (Timeline)

• Archaean (3.8-2.5 bya):
  • First cells (prokaryotic).
  • Anaerobic organisms.
  • Heterotrophs (energy from consumption).
• Proterozoic (2.5 bya - 543 mya):
  • Multicellular eukaryotes arise.
  • Possible origins: colony formation, single cells staying stuck together.

Phanerozoic Eon - Diversification

• Diversification of invertebrates and colonization of land plants and animals.
• Cambrian (543–490 mya):
  • Abrupt increase in marine invertebrate diversity
• Ordovician:
  • Diverse group of marine invertebrates (trilobites, brachiopods).
  • Primitive land plants and arthropods invade land, mass extinction at end.
• Silurian:
  • Coral reefs appear.
  • Colonization by terrestrial plants and animals (spiders and centipedes).
• Devonian:
  • Ferns, horsetails, seed plants appear.
  • Insects, tetrapods (amphibians) emerge.
• Carboniferous:
  • Rich coal deposits formed.
  • Large plants, trees, amphibians present.
  • First flying insects.
  • Amniotic egg emerges.
• Permian:
  • Pangaea (continent formed).
  • Amphibians, reptiles became dominant.
  • Mammals-like reptiles appeared.
• Triassic:
  • Many reptiles.
  • First dinosaurs and mammals, gymnosperms (non-flowering plants) dominate.
• Jurassic:
  • Gymnosperms dominate.
  • Dinosaurs dominate.
  • First known birds appear.
• Cretaceous:
  • Dinosaurs still dominant, earliest flowering plants (angiosperms).
  • Mass extinction at end (K-T extinction).
• Tertiary:
  • Mammals diversified rapidly, angiosperms dominate.

Lecture 5 - Introduction to Evolution

• Evolution: Heritable change in one or more characteristics of a population through generations.
• Microevolution: Changes in allele frequencies in a population over time.
• Macroevolution: Formation of new species/groups of related species.
• Theory: Comprehensive explanation for a large body of information.

Darwin's Influences and HMS Beagle

• Uniformitarism: time required for Earth's geological changes.
• Slow geological processes lead to substantial change.
• Population growth linked to limited resources.
• Darwin's observations on animals and plants on his voyage influenced his theory.

Darwin's Formulation of Theory

• Mid-1840s: Darwin formulated his theory.
• 1858: Alfred Wallace also developed similar theory; papers published together.
• 1859: Darwin's "The Origin of Species" published.

Descent with Modification

• Variation within a species; heritable traits.
• More offspring produced than can survive; competition for resources.
• Traits favoring reproductive success become more common.

Fossils (Transitional Forms)

• Fossils document evolutionary changes.

Biogeography

• The study of the geographical distribution of extinct/living species.
• Isolated continents and islands have unique plant and animal communities.
• Convergent evolution: similar characteristics from different lineages.

Selective Breeding (Artificial Selection)

• Programs/procedures to modify traits in domesticated species.
• Breeders chose desirable phenotypes (e.g., leg-length, size, hairiness).

Homology - Anatomical, Developmental, Molecular

• Fundamental similarity due to descent from a common ancestor.
• Similar structures may have different functions.
• Species from different lineages sharing similar structures.