3/22/19 Evidence of Evolution Learning Objectives ▪ Describe how the geologic distribution of species today relates to their evolutionary history. ▪ Identify how fossils help document the descent of modern species. ▪ Explain what homologous structures and similarities in development suggest about the process of evolutionary change. ▪ Describe how molecular biology can be used to trace the process of evolution. ▪ Explain what recent research of the Galápagos finches show about natural selection. Biogeography Evidence From Fossils Patterns in the distribution of fossils and living species, Ambulocetus could combined with information from geology, tell us how modern both swim in shallow Rodhocetus water and walk on land. probably spent organisms evolved from their ancestors. most of its time in water. Ambulocetus Pakicetus Rodhocetus Ancient artiodactyl Evidence of Whale Evolution Homologous Structures Modern whales have • Similar structures that are shared by related ancient structures species and have been inherited from an common ancestor Odontocetes Basilosaurus Mysticetes only swims. Modern whales Dorudon Basilosaurus 1 3/22/19 Homologous Structures Vestigial Structures Homologous structures inherited from ancestors, but have lost much of their original size and function Examples: ear wiggling muscles, pelvic and thigh bones in cobras and whales Vestigial Structures Analogous structures • Body parts that serve similar function, but do not share structure and development • Unrelated species • Examples: • Bat wings and bird wings • Cacti and euphorbia Embryology and Development Genetics and Molecular Biology Similar patterns of embryological development provide At the molecular level, overwhelming similarities in the further evidence that organisms have descended from a genetic code of all organisms, along with homologous genes common ancestor. and molecules, provide evidence of common descent. •All living cells use information coded in DNA and RNA to carry information from one generation to the next and to direct protein synthesis •Genetic code is nearly identical in almost all organisms 2 3/22/19 Testing Natural Selection 3.