Evolutionary Evidence

Evidence for Evolution 5 scientific disciplines: 1.Paleontology 2.Biogeography 3.Embryology 4.Comparative anatomy 5.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 Fossil record used to establish evolutionary relationships and descent with modification Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Moeritherium Barytherium Deinotherium Mammut Elephas maximus (Asia) Stegodon Mammuthus Loxodonta africana (Africa) Loxodonta cyclotis (Africa) Millions of years ago Years ago Platybelodon

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

? ? ? ? Where are the transitional fossils?

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 Colored Leaves Needles Tendrils

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 Closely related species have sequences that are more similar than distantly related species  DNA & proteins are a molecular record of evolutionary relationships Closely related species have sequences that are more similar than distantly related species  DNA & proteins are a molecular record of evolutionary relationships Millions of years ago Horse/ donkey Sheep/ goat Goat/cow Llama/ cow Pig/ cow Rabbit/ rodent Horse/cow Human/rodent Dog/ cow Human/ cow Human/kangaroo Nucleotide substitutions

Comparative Hemoglobin Structure Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans 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