OBJECTIVE 6 NOTES Evolution, Natural Selection & Adaptations 1. Vocab a) Evolution A genetic change in a population over time Note: individuals do not evolve, only populations show change b) Theory A well supported explanation of a scientific phenomenon c) Fitness The ability of an organism to survive and reproduce in a given environment 2. Charles Darwin From , a young naturalist called Charles Darwin toured the world in HMS Beagle. Where food was limited, competition meant that only the fittest would survive. This would lead to the natural selection of the best adapted individuals 3. Assumptions of the Evolutionary Theory The earth is billions of years old Time + small changes = large changes Mutations can be beneficial 3. Natural Selection The process by which individuals that are better suited to their environment survive and reproduce most successfully Also called: Survival of the Fittest Artificial Selection 3. Natural Selection Types 4. Mechanisms of Evolution Genetic Variation Mutations Meiosis (crossing over) Natural Selection Reproductive Isolation 5. Evidence of Evolution Fossil Records Homologous Structures Analogous Structures Vestigial Structures DNA Fossil Record Fossils are preserved evidence of dead organisms Assumes that it takes a long time for sediment to accumulate Assumes that the dead organism had offspring Assumes that there are millions of years separating each sediment layer. Homologous Structures Structures that have a similar structure (anatomy) from one organism to another. Example: limbs Human leg v. Whale flipper Both contain bones called femur, tibia, fibula, etc. Similar structure but different functions Analagous Structures Structures that have a similar function (physiology) but different structure between organisms. Example: Wings Butterfly wing v. Bird wing Both enable flight, but are very different structures Vestigial Structures Defined as a structure that serves no useful function in an organism. Most common citations of this are not accurate: Coccycx: without it humans cannot pass solid waste. Appendix: might have immune/lyphatic functions Tonsils: have immune and lyphatic functions Eyebrow/lash: keeps sweat/dust/particles out of eyes Body Hair: mechanoreceptors at base, traps heat, offers protection from sun rays