evolution
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Evolution. The Evidence. ‘Evolution’ stands for several theses: . Mutability of species (i.e. species change over time) (observed/confirmed) Natural selection (observed/confirmed) - PowerPoint PPT PresentationTRANSCRIPT
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Evolution
The Evidence
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‘Evolution’ stands for several theses:
• Mutability of species (i.e. species change over time)– (observed/confirmed)
• Natural selection – (observed/confirmed)• Community of descent (i.e. all life forms share a
common evolutionary history ; all forms are related by descent)
– Including humans and chimpanzees; humans and fish; humans and turnips; humans and bacteria
– (inference; but based on diverse and compelling evidence)– (indirectly observed/indirectly confirmed)
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Evidence for evolution1. Fossil Record2. Vestigial Structures3. Skeletal Homologies4. Embryological Homologies5. Cellular Homologies6. Genetic Homologies7. Imperfect Design (Dysteleology)8. Observed instances of origin of new species
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Fossil record
Archaeopteryx, dinosaur-bird transition
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Fossil record
Tiktaalik rosae, fish-land vertebrate transition found Canadian Artic 2004
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Vestigial structures
Vermiform appendix
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Vestigial structures
Hand bones
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Skeletal homologies
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Embryological homologies
Haeckel 1874
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Embryological homologies
Richardson et al 1997
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Cellular homologies
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Genetic homologies1. All living things use same genetic code: DNA,
RNA2. All living things employ same 20 amino acids to
form proteins3. All living things use only right-handed molecules4. Homologous proteins and genes found in
organisms as widely different as humans, fruitflies, tulips, brewers yeast, and bacteria
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Genetic homologies
Human-chimp 98% overlap
Same base-pair errors occur in human & chimpanzee pseudo-genes: Coincidence?
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Missing Human Chromosome Pair
If humans and other apes evolved from a common ancestor why do we have only 23 chromosome pairs to chimps’ 24?
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Tinkering
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Dysteleology (poor design)
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Dysteleology (poor design)
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Dysteleology (poor design)
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Dysteleology (‘tinkering’)
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Dysteleology (‘tinkering’)
• Eukaryotic cells (like ours) a symbiotic merger of several previously independent prokaryote bacteria
• Mitochondria (animals)• Chloroplasts (plants)• Centrioles, nucleus too?
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Poster child of tinkering
Symbiotic merger of at least 4 separate organisms; 5 counting mitochondria
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Have we ever observed the origin of any new species?
• First, what do we mean by a species?• Morphological species concept: based on
observable body shape, size, markings etc.• Reproductive species concept: two organisms
are of the same species if they can successfully produce fertile offspring
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Origin of new species observed
Polyploidy = chromosome # increase (genome doubling etc.; common in plants; but also seen in amphibians, fish)
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Origin of new animal species observed
• Fruitflies• Mosquitoes• Cichlid fishes• Amoeba-bacteria
symbiont