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16.4 – Evidence of Evolution 16.4 Evidence of Evolution 16.4 – Evidence of Evolution Biogeography Biogeography - is the study of where organisms live now and where they and their ancestors lived in the past. 16.4 – Evidence of Evolution Closely Related, but Different Same ancestor, but adapted to different environments. Black-tailed Jackrabbit Snowshoe Hare Classification = Same Genus (Lepus) – Different Species 16.4 – Evidence of Evolution Distantly Related, but Similar Different ancestors, adapted to similar environments Differences point to different ancestors Similarities caused by similar environments. Example: Rhea, Ostrich, & Emu Classification = Different Order, Genus & Species 16.4 – Evidence of Evolution The Age of Earth Geologists now use radioactivity to establish the age of certain rocks and fossils. = Radioactive Dating Earth is about 4.5 billion years old 16.4 – Evidence of Evolution Fossil Evidence 3.8 billion years: oldest fossil evidence Prokaryotes are the oldest form of life Location of eukaryotes in strata suggests they evolved from prokaryotes Fossils link life forms from past and present (whales) 16.4 – Evidence of Evolution Recent Fossil Finds One recently discovered fossil series documents the evolution of whales from ancient land mammals. 16.4 – Evidence of Evolution More Recent Fossil Finds Other recent fossil finds link: Dinosaurs and Birds Fish and four-legged land animals. The fossil evidence we do have suggests an unmistakable story of evolutionary change. 16.4 – Evidence of Evolution 16.4 – Evidence of Evolution Homologous Structures Homologous structures = Structures that are shared by related species and that have been inherited from a common ancestor. **Common structure, not common function.** The bones in the forelimbs of mammals all have the same basic pattern. 16.4 – Evidence of Evolution Analogous Structures Analogous structures = Body parts that share a common function, but not structure, and different ancestry. 16.4 – Evidence of Evolution Vestigial Structures Vestigial structures = are inherited from ancestors, but have lost much or all of their original function in the descendent. The hipbones of bottlenose dolphins Ear muscles, appendix, and others in humans. 16.4 – Evidence of Evolution Embryology Researchers noticed that the early developmental stages of many vertebrates look very similar. Similar patterns of embryological development provide further evidence for a common ancestor. 16.4 – Evidence of Evolution Life’s Common Genetic Code All living cells use information coded in DNA and RNA to carry information from one generation to the next. It is nearly identical in almost all organisms, including bacteria, yeasts, plants, fungi, and animals. 16.4 – Evidence of Evolution Homologous Molecules Homologous proteins share extensive structural and chemical similarities. Cytochrome c, is a protein found in almost all living cells, and is very similar in structure in all organisms. Ex. Bakers yeast and human cells Developmental genes called HOX genes are similar in multicellular animals. 16.4 – Evidence of Evolution Testing Natural Selection The Grant’s tested Darwin’s idea of natural selection. The data shows that individual finches with different-size beaks have better or worse chances of surviving both seasonal droughts and longer dry spells. Less food = Bigger beak greater chance of survival 16.4 – Evidence of Evolution Testing Natural Selection The Grants’ data confirmed that competition and environmental change drive natural selection. Without heritable variation in beak sizes, the finch species would not be able to adapt to a change in the environment.