Darwin argued that living things had been evolving on the Earth for millions of years. • What was his evidence?
Evidence of Evolution • Fossil Record • Geographic Distribution • Anatomy • Embryology • Biochemistry
Fossil Record • FOSSILS–preserved remains or imprints of ancient organisms that reveal changes in populations over time
Problems with the Fossil Record • Weathering and erosion damages fossils • Some organisms do not fossilize well due to their soft bodies • Conditions necessary for fossil formation are rare
Geographic Distribution • Species now living on different continents had each descended from different ancestors. • Similar conditions caused different animals to evolve with certain features in common. • Leads to speciation
Geographic Distribution Speciation • The evolution of one or more species from a single ancestral species • When populations becomes separated and can no longer interbreed and produce fertile offspring\ • Gene pool- consists of ALL the genes, including ALLELES, that are present in a population
A few finches travel from South America to one of the islands. There, they survive and reproduce. Some birds from species A cross to a second island. The two populations no longer share a gene pool. Seed sizes on the second island favor birds with larger beaks. The population on the second island evolves into a population B, with larger beaks. Eventually population A and B evolve into separate species.
Anatomy • Homologous Structures • Structures found in different species that are inherited from a common ancestor • Examples: Human arm, Bat wing, Whale arm
Anatomy • Vestigial Structures/ Vestigial Organs • Inherited Structures that are reduced in size and unused Examples: • Femur in whales • Hip joint in snakes • Wisdom teeth and appendix in humans
Embryology • Embryology- The study of the early stages of development • The same groups of embryonic cells develop in the same order and in similar patterns • This produces homologous structures
How could the study of embryos help show the relationships among animals with backbones? Chicken Embryo Turtle Embryo Rat Embryo
Evolutionary similarities can be seen between organisms by comparing their DNA Biochemistry- • The more similarities between the base sequences of DNA (A, T, C, G) then the closer the evolutionary relationship between two organisms
Look at the table below to compare amino acid differences between four different species compared to humans.Which species is the most similar to humans?
Mutations in Bacterial DNA lead to drug resistanceHow does this graph show the evolution of bacteria?