True or False? We know what it is, we ve seen the evidence, but Aim: How does evolution happen? Charles Darwin was the 1 st scientist to offer an explanation for how Evolution happens. Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck 1744 1829 Lamarck s Theory of Evolution 1
Lamarck s Theory If Lamarck was right Lamarck thought: Organisms lose or gain traits during their lifetime. They will gain helpful traits and lose bad ones. This gets passed on to their children. ALL WRONG! L Charles Darwin 1809-1822 The father of evolution Trip to the Galapagos Islands Charles Darwin traveled to the Galapagos islands, a uninhabited environment, where he studied evolution. 2
Theory of Evolution by Natural Selection According to this theory Evolution is controlled by NATURE Organisms with helpful new traits that are able to SURVIVE and REPRODUCE will pass on these changes to their children Conditions that are needed for Evolution to occur: 1) Lots of babies need to be made 2) There needs to be a variety of babies made 3) Some of these babies have special new traits that help them survive 4) The babies with these new awesome traits pass them to their kids, while the old babies who haven t changed die out L Over time the population changes Overproduction More offspring are produced than can survive (most of them die young L ). Ex: Bacteria, fish, insects, and rabbits make a lot of babies because the chance that their young will survive is small Variation: Variety is necessary Variation: Individuals have differences in their genes causing differences in their appearance Where does the variety come from? Sexual Reproduction: there are tons of sperm/egg combinations that s a lot of variety! Mutation (changes in DNA): causes new traits! 3
Mutations Mutations change the sequence of bases in DNA. Most mutations are HARMFUL, but some can create awesome NEW traits that help the organism SURVIVE. Adaptation Adaptation: an awesome trait that helps an organism survive. Ex: Camouflage VARIATION increases the chance that some members will have a positive variation an adaptation. Mutation- makes bones stronger Survival of the Fittest Best Adapted To Survive In nature there is a struggle for survival Only those BEST adapted to their environment will survive. (There is not enough food/water/space/oxygen for everyone to live) 4
Fit Strong How fast does evolution The ENVIRONMENT chooses which traits have adaptive value. happen? Organisms with these valuable traits live, others die L Two Patterns Of Change Example Types: 1) Gradualism evolution occurs slowly & steadily through time 2) Punctuated Equilibrium- species stay the same for long periods of time and then change rapidly. No Change No Change No Change ------------- ----------- ------------- 5
Antibiotic Resistance Ex: Punctuated Equilibrium When bacteria are exposed to an antibiotic there is a chance that a few will have a gene that makes them resistant (protected from antibiotic) What happens If a species can t evolve or adapt to its environment??? Antibiotic X Resistant Bacteria Extinction Artificial Selection vs. Natural Selection The disappearance of an entire species ex: dinosaurs They don t have an ADAPTATION to survive temperature changes, pollution, etc. People select the desirable traits that will appear in the offspring Environment selects the desirable traits that will appear in the offspring. 6