Evolution How do organisms change?

Some basic ideas Evolution is the change in characteristics of a species over time Remember a species is a group of organisms that share similar characteristics and can reproduce An adaptation is anything that makes an organism better suited to its environment

2 Theories of Evolution Lamarck Aquired characteristics is the idea that you will inherit the exact traits that your parents have His theory was NOT accepted Darwin Natural selection is his idea He studied finches and other species of plants and animals on the Galapagos Islands His theory is accepted

Natural Selection This was Darwin’s hypothesis It is the idea that organisms with the traits best suited to their environment will survive and reproduce Variations are any adaptations that make an individual different from others of the same species Darwin's Finches & Natural Selection - Biology OnlineDarwin's Finches & Natural Selection - Biology Online

Speed of Evolution vs. Speed of Adaptation Evolution Happens slowly 2 models to explain this: –Gradualism a slow ongoing process –Punctuated equilibrium a mutation can make a new species in a short amount of time Adaptation Happens more quickly “instant” changes –Ex. Cold room and you get a sweatshirt or leaving for lunch on the first bell

Evidence for Evolution Vestigial structures: structures in the body that no longer serve a purpose –Appendix in humans, pelvic bones in whales Embryology: study of embryos and their development Homologous structures: body parts that are similar in structure –Human hand, dolphin flipper, bat wing…bones same in function too DNA: similar hereditary material suggest common ancestry Fossils: most evidence for evolution comes from these One Species, Living Worldwide | Smithsonian Human Origins Program