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Evolutionary Evidence Evidence for Evolution • 5 scientific disciplines: 1. 2. 3. 4. 5. Paleontology Biogeography Embryology Comparative anatomy Molecular biology Paleontology • Fossil Record to reveal prehistoric existence of extinct species – Study changes of species or formation of new species • Dating to find the “age” of fossils Fossil Record • Fossils found in layers of sedimentary rock – New layers form over old layers = creates record over time – Shows succession of organisms that populated Earth over long periods of time – Can determine “timeline” of fossils = relative dating Fossil Record Dating • Relative dating = using sedimentary rock to find the relative “timeline” of organism • Absolute dating = using radioactive isotope decay (C-14) to determine the date of organism Uses Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) • Fossil record used to establish evolutionary relationships and descent with modification Moeritherium Barytherium Deinotherium Mammut Platybelodon Stegodon Mammuthus Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa) 34 24 Millions of years ago 5.5 2 1040 Years ago Evolutionary Change in Horses Evolution of Birds • Archaeopteryx • • Lived about 150 mya Links reptiles and birds • Bony tail, teeth, and feathers Early Tetrapod • 2006 Fossil Discovery • Tiktaalik • Missing link from sea to land animals ? ? ? ? Biogeography • Using geography to determine evolutionary patterns – Discovered: unrelated species have similar characteristics when found in similar environments • Natural selection Embryology • Similar stages of development (ontogeny) among related species – Help with phylogeny • All vertebrate embryos = similar structures at different stages of development – Gill slits, tail, etc. Embryology Gill slits Post-anal tail Chick embryo Human embryo Comparative Anatomy • 2 kinds of structures that contribute to identify evolutionary relationships among species – Homologous structures – Analogous structures Homologous Structures • Similar characteristics resulting from common ancestor Homologous Structures • • • • Similar structure Similar developments Different functions Close evolutionary relationship – Common ancestor Homologous Structures Spines Leaves Succulent Leaves Tendrils Needles Colored Leaves Homologous Structures • Some species have vestigial structures – No longer serving a function • Ex. snakes, whales, wings, appendix Why would whales have pelvis & leg bones if they were always sea creatures? Analogous Structures • Resemble other structures in different species – Not because of common ancestor Don’t be fooled by their looks! Analogous Structures • Separate evolution of structures – Similar functions – Similar external form – Different internal structure – Different ancestors Molecular Biology • Comparing DNA and Protein Structure – Universal genetic code: DNA & RNA – Compare common genes Human/kangaroo Closely related species have sequences that are more similar than distantly related species DNA & proteins are a molecular record of evolutionary relationships Nucleotide substitutions 100 Dog/ cow 75 Human/ cow Rabbit/ rodent Llama/ cow Horse/ donkey 50 Horse/cow Sheep/ goat 25 Human/rodent Pig/ cow Goat/cow 0 0 25 50 75 Millions of years ago 100 125 Comparative Hemoglobin Structure 8 0 10 32 45 67 30 70 50 125 90 110 120 Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans Molecular Biology • Analysis of phenotypic and allelic frequencies • Humans can select for “advantageous” traits “descendants” of wild mustard “descendants” of the wolf