Aim: How does evolution occur by natural selection?

How Does Evolution Occur? EVOLUTION is a slow change in a _________ over time. Evolution occurs by a process called _________________________. species NATURAL SELECTION Read this cartoon, what do you think NATURAL SELECTION is?

Lamarck’s theory of Evolution Lamarck believed that by the selective USE or DISUSE of characteristics, organisms lost or acquired certain traits that would be passed on to the offspring.

Darwin Considered the “_________” of evolution. Charles Darwin traveled to the ___________________ , an uninhabited environment, where he studied evolution (_________________) father Galapagos islands Darwin’s Finches

Natural Selection KEY NATURAL SELECTION is the _________ to Darwin’s theory. According to this theory, evolution is controlled by __________ . Only the organisms that are able to ___________ and ________________ will pass on their genes. NATURE SURVIVE REPRODUCE

Natural Selection vs. Artificial Selection ________ select the desirable traits that will appear in the Offspring. People ____________ selects the desirable traits that will appear in the offspring. Environment

Conditions that are vital to Evolution: Overproduction Variation Struggle For Survival Best Adapted To Survive Darwin did NOT have knowledge of the _________ basis of inheritance genetic

Overproduction leads to More offspring are produced than can ___________ (most die young). Organisms such as bacteria, fish, insects, and rabbits have ________ reproductive rates because the chance that their young will survive is___________. survive Overproduction leads to COMPETITION!! high minimal

Variation Variation: Individuals have__________ in their appearance, structure, or genes. Source of variation: _______ Reproduction (sperm + egg) __________ (Indp. Ass. & Crossing Over) __________ (Change in DNA) differences Sexual Meiosis Mutation

Mutations change the base sequence of ________. DNA Most mutations are ___________, but some can help the organism ____________. DNA HARMFUL SURVIVE

Best Adapted To Survive The __________________ chooses which traits have adaptive value. An individual that has traits favorable in a certain environment will live to _____________ and pass on those traits, others will _____ out. ENVIRONMENT reproduce die

Struggle For Survival “Survival of the fittest” Only those _________ suited will survive because of competition for ______ (limited) resources (___________________________) BEST finite oxygen, water, food, and shelter

Patterns Of Change SHORT Species with ________ reproductive cycles that produce ________ offspring tend to evolve more ________ than species with _________ life spans and ______ offspring. Types: a) Gradualism – evolution occurs _________ through time (Slow & Continuous) . b) Punctuated Equilibrium- species stay the same for long periods of time and then change _______. MANY quickly LONG FEW steadily rapidly

Examples of Natural Selection Industrial Melanism Antibiotic / Pesticide Resistance

Antibiotic Resistance Ex: Punctuated Equlibrium When bacteria are exposed to an antibiotic there is a chance that a few will have a gene that makes them ____________. The bacteria ___________ the resistance will be killed, while those that are __________ will ________ and pass on their genes for antibiotic resistance. RESISTANT WITHOUT RESISTANT survive The antibiotic is the selecting agent Resistant Bacteria Antibiotic X

Extinction disappearance The ______________ of an entire species (ex. Dinosaurs) It can be caused by _______________________________________ ___________________ temperature changes, pollution, or landscape changes