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Evolution and Diversity Lecture 2.docx

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BIOL 103
Peter T Boag

Evolution and Diversity Lecture 2 - Fossil intermediates o E.g. evolution of whales o Whales and hippos evolved in parallel from ancient Artiodactyls (cloven-hoofed mammals) - Deep Time o Difficult for us, impossible for Darwin to grasp vast time spans available for evolutionary change - Darwin familiar with results of plants and animal breeding, done empirically, without knowledge of genetics - Geographic distribution and Evolutionary history o Darwin saw other species distributed around the Earth – now that we know about plate tectonics we know more about this idea o Darwin did not understand plate tectonics o Knew about beaches being raised over night, and even more over time made him realize that the Earth was very dynamic (plated could move, lands could change) so natural selection made sense - Artificial Selection on Wild Brassica: Process o Parental generation: select individuals with the largest and most compact flowering stalks, and breed them o Generation 2: of the offspring, select the individuals with the largest and most compact flowering stalks, and breed them o Generation 3: do as what was done in generation 2 o Generation 4: after many generations, average flowering stalks are much larger and more compact - Artificial Selection in Brassica: Results o Flowers: broccoli and cauliflower o Stems: kohirabi o Terminal bud: cabbage o Leaves: kale o Axilliary buds: Brussels sprouts o They all look like a different species, but all the same different phenotypes exaggerated by artificial selection - Evidence of Evolution: comparative anatomy o Homologous features  Derive from same structure in common ancestor o Homoplastic (analogous) features  Similar functions in distantly related organisms result of convergent evolution o Vestigial Structures  Remnants of structures indicate adaptations wax and wane as environments change o Many results are from parallel selection, not necessarily common ancestry - Homology in Animal Genes o Homologous traits: similarities are inherited from a common ancestor o There is a change in how they are regulated which is how development changes - Homoplastic (analogous) phenotypes can be misinterpreted as homology o Analogous Traits: similarities result from convergent evolution o Common dolphin and Ichthyosaur look similar and have a similar function, but they have a different ancestor - Convergent Evolution: unrelated mammals eat ants and termites in similar ways and display many other structural and functional similarities - Goose bumps are vestigial trait o Human goose bumps are note useful to humans o For other animals, goose bumps are useful o Erect hair on chimp (insulation, emotional display) - Appendix is a vestigial trait in humans o They are involved in digesting cellulose material o Smaller in humans because of our diet – it can cause problems (appendicitis) o In stone age time, we could get cholera, would loose bolily fluids, appendix used for something after intestinal disease - Evidence for evolution from developmental and molecular biology o Development reveals ancestral structures no longer obvious in adults o Protein and DNA sequences contain records of evolutionary change o Phylogency  Evolutionary history of group of related species, displayed as Phylogenetic trees  Diagrams showing lines of descent based on molecular data (more lat
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