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• Evolution is the change of genetic makeup of an organism in a population over a period of time
• Microevolution refers to small scale changes affecting one or few genes in a short period of time
• Macroevolution refers to large scale changes over a long period of time
• Biogeography: The distribution of organisms based on geographic evidence followed a pattern connected to the movement of tectonic plates over geologic time
• Species that evolved before the breakup of Pangaea tend to be distributed worldwide
• Species that evolved after the breakup of Pangaea tend to be visible in smaller regions on Earth
• Example: presence of marsupials in Australia while other mammals are placental
• Marsupial species in Australia are diverse and play a wide range of ecological roles
• Darwin’s finches, marsupials in Australia, and many other species found in some islands are unique on the island’s settings but have distant relationships to ancestral species on mainlands
• Fossil Record: Preserved remains of traces of living organisms dating from the distant past
• Fossils - Insights on the evolution of long timescales
• Age of a fossil can be determined by locating the remains in rock layers called strata
• Strata give information on the timeline, with younger layers on top and older layers on the bottom
• Fossils in different strata but located on the same site can be classified by their position
• Example: lineage of the horse family, used to reconstruct the family tree of horses and their extinct relatives
• DNA Sequence: All organisms share the same genetic material (DNA), genetic codes, process of gene expression, and molecular building blocks like amino acids
• Living things descended from a common ancestor with DNA expressed by genes through transcription and translation
• Embryology: Some structures are only present during the embryologic stage
• All vertebrate embryos have tails and slits during development
• Some organisms have body parts that have lost their ancestral function, often reduced in size and called vestigial organs
• Homology: If two species have the same physical features, they may have the same ancestor
• Physical features shared because of evolution are homologous
• Example: forelimbs of birds, whales, humans, and dogs have similar bone patterns showing they may have the same ancestor
• Birds are commonly thought to be direct descendants of dinosaurs