Evolution The Evidence

‘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)

Evidence for evolution 1. Fossil Record 2. Vestigial Structures 3. Skeletal Homologies 4. Embryological Homologies 5. Cellular Homologies 6. Genetic Homologies 7. Imperfect Design (Dysteleology) 8. Observed instances of origin of new species

Fossil record Archaeopteryx, dinosaur-bird transition

Fossil record Tiktaalik rosae, fish-land vertebrate transition found Canadian Artic 2004

Vestigial structures Vermiform appendix

Vestigial structures Hand bones

Skeletal homologies

Embryological homologies Haeckel 1874

Embryological homologies Richardson et al 1997

Cellular homologies

Genetic homologies 1.All living things use same genetic code: DNA, RNA 2.All living things employ same 20 amino acids to form proteins 3.All living things use only right-handed molecules 4.Homologous proteins and genes found in organisms as widely different as humans, fruitflies, tulips, brewers yeast, and bacteria

Genetic homologies Human-chimp 98% overlap Same base-pair errors occur in human & chimpanzee pseudo-genes: Coincidence?

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?

Tinkering

Dysteleology (poor design)

Dysteleology (‘tinkering’)

Eukaryotic cells (like ours) a symbiotic merger of several previously independent prokaryote bacteria Mitochondria (animals) Chloroplasts (plants) Centrioles, nucleus too?

Poster child of tinkering Symbiotic merger of at least 4 separate organisms; 5 counting mitochondria

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

Origin of new species observed Polyploidy = chromosome # increase (genome doubling etc.; common in plants; but also seen in amphibians, fish)

Origin of new animal species observed Fruitflies Mosquitoes Cichlid fishes Amoeba-bacteria symbiont