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Evidence of Evolution Theory of Evolution • Charles Darwin is considered the founder of modern evolution – The Origin of the Species – Natural selection – Galapogos Islands: Studied plants and animals • Finches The Theory of Evolution • Natural Selection – Species with best traits for the environment survive and reproduce – Less-favorable variations have less chances of surviving and reproducing – Variations also called adaptations Evidence to support Evolution • Fossils •DNA sequences •Anatomical Similarities •Developmental Similarities Fossils • Principle of Superposition – Lower layers are older – Higher layers are younger – Fossils relative age can be determined B A • Radioactive Dating – Uses radioactive isotopes to determine age Horse Fossils Whale Fossils DNA Sequences • Order of nitrogenous bases that make up rungs of DNA – A’s, T’s, G’s, C’s • Determines amino acid sequence that makes proteins • More similar the DNA or amino acid sequence the more closely related the organisms Anatomical Similarities • Homologous Structures – Similar structure but different functions • Analogous Structures – Similar function but different structures – Do not indicate common ancestors • Vestigial Structures – remains of a structure that was functional in some ancestors but is no longer functional in the organism in question Homologous Structures Analogous Structures Vestigial Structures Pelvis in whales Eye bulbs in blind cave dwelling animals Boa – pelvis, hind leg Vestigial Structures in Humans • Ear wiggling muscles – Three small muscles around each ear – Allowed movement of ears towards sound • Coccyx – Tail bone • Appendix – Believed to have had a digestive function • Wisdom teeth – Molars – Often removed due to lack of space in mouth Developmental Similarities • Embryology – Study of development of embryos • Similar embryo development more closely related Phylogeny • Evolutionary history of organisms • Organizes organisms based on their evolution • Shown on phylogenetic tree – Branching diagram showing hypothesized evolutionary relationships – May include extinct and living organisms Phylogenetic Trees •Common ancestor is at base •Most modern organisms shown on tips of branches •Each division represents evolution of new species Cladogram • Shows relationships based on observable characteristics • Only shows existing species Cladogram Primate Cladogram
