1. Ch. 25 – The History of Life on Earth

2. Lost Worlds Macroevolution Broad pattern of evolution above the species levels Terrestrial vertebrates Mass extinctions Origin of key adaptations

3. Early Earth 3.5 billion year old fossils 4 main stages: 1.Abiotic synthesis of small organic molecules 2.Joins of the small molecules into macromolecules Abiotic synthesis of RNA monomers 3.Packaging of molecules into protocells Reproduction and metabolism must be carried out simultaneously Vesicles 4.Origin of self-replicating molecules that eventually lead to inheritance ribozymes

4. Fossil Record Sedimentary rocks richest source of fossils Great changes in the kinds of organisms on Earth at different points in time Incomplete chronicle Dating fossils relative dating –compare strata –only relative Radiometric dating –assign age in yrs. –Based on radioisotopes and half life

5. Fossil Record Substantial chronicle of evidence Phylogeny has a biogeographical basis in continental drift –spatial distribution of life Mammals –Tetrapods –Mandible bone –Middle ear bones –Mammalian’s teeth

6. Origin of Single-celled and Multicelled Organisms and Colonization of the Land Geologic record Three eons –Archaean –Protozoic –Phanerozoic Paleozoic Mesozoic Cenozoic

7. First single celled organisms Two rich sources for early prokaryote fossils are stromatolites (fossilized layered microbial mats) and sediments from ancient hydrothermal vent habitats. 3.5 billion years ago Found today in warm, salty bays Fig. 26.4

8. Recent fossil finds from China have produced a diversity of algae and animals from 570 million years ago, including beautifully preserved embryos (SEM). Fig. 26.7

9. Photosynthesis and the Oxygen Revolution Oxygen gas Produced from photosynthesis First Eukaryotes 2.1 billion years old Endosymbiotic theory Serial endosymbiosis

10. Origin of Multicellularity 1.5 billion years ago Why were they limited in size until about 535 million years ago? Severe ice ages Cambrian explosion Colonization of Land 500 million years ago

11. Speciation and Extinction Rates Plate Tectonics Continental drift

12. Speciation and Extinction Rates Mass Extinctions “Big Five” Mass Extinction Events

13. Speciation and Extinction Rates Adaptive Radiations Occurred after each mass extinction Worldwide Regional

14. Major Changes in Body Form can Result from Changes in the Sequences and Regulation of Developmental Genes Heterochrony Evolutionary change in the rate or timing of developmental events

15. Major Changes in Body Form can Result from Changes in the Sequences and Regulation of Developmental Genes Paedomorphosis Sexually mature features may be retained from juvenile structures

16. Major Changes in Body Form can Result from Changes in the Sequences and Regulation of Developmental Genes Homeotic genes Master regulatory genes Control the placement and spatial organization of body parts Hox genes –Provide positional information in an animal embryo

17. Major Changes in Body Form can Result from Changes in the Sequences and Regulation of Developmental Genes Evolution of Development Changes in genes Changes in gene regulation

18. Evolution is NOT Goal Oriented Evolutionary novelties Eye –Patch of pigmented cells –Eyecup –Camera type eye –Eye with primitive lens –Complex camera lens- type eye –Still maintain function of vision Exaptations

19. Evolution is NOT Goal Oriented Evolutionary Trends Evolution of the horse Result of interactions between organisms and their current environments If environment changes trend may cease or reverse