Major Theories of Evolution
EVOLUTION the e word EVOLUTION simply means: The change of organisms over time. Believing in evolution means you believe organisms change
THEORY 1: Theory of Acquired Traits - From Lamarck (1744-1829) -suggested that: Traits not determined by genes. Traits develop during your life and are passed on to offspring.
Examples of Lamarck s Theory 1) Webbed feet come from the ducks stretching the skin between their toes Babies of stretched ducks also have stretched feet
DISCUSS -- How Would Lamarck People who get tattoos in life Explain These Examples? People who have cosmetic surgery
SO what is the final verdict?? Theory 1: Theory of Acquired Traits IS WRONG!!! PROVEN TO BE AN INCORRECT THEORY!!
Theory 2: Theory of Evolution by Natural Selection From Charles Darwin (1809-1822) - British scientist 1831 - traveled on HMS Beagle for 5 years as the naturalist Collected organism & rock samples 1835 -- Visited the Galapagos Islands (off coast of Ecuador) Became inspired here to develop his theory of natural selection 1859 published ideas in Origin of Species
THE BASIC IDEAS BEHIND NATURAL SELECTION Nature produces variation in organisms Example: different hair colors; different sizes of heads Each individual is born with a set of traits If you have successful traits, you live longer, reproduce, and pass traits onto babies If you have harmful traits,you die or reproduce slowly, not passing on traits Over time, successful traits show up more and more.
Four Principles of Natural Selection 1. OVERPRODUCTION Populations produce more offspring than can survive. 2. VARIATION Individuals in a population differ from each other, in some way.
3. HERITABILITY Variations are inherited from the parents. You cannot CHOOSE and CHANGE traits. 4. REPRODUCTIVE ADVANTAGE Some variations allow organisms to have more babies and reproduce more.
What makes variation? ANSWER: Mutations! A mutation is a change in a DNA sequence If you are a mutant, you are NOT jacked up. You simply have a different trait than the norm Some mutations are helpful others harmful Most mutations tend to be harmful You don t choose your mutations.
Random Mutation Picture Page!! GOOD TIMES! EEK!!!
What is the verdict on Theory 2? The theory of Natural Selection: The VERDICT is: <drum roll, please> IT HAS NOT BEEN PROVEN INCORRECT!!! For over 150 years, scientists have found LOTS of evidence for this theory and use it as the standard theory to explain evolutionary change. As with ALL theories, it could be proven wrong, IF there is adequate evidence to show a different theory provides a better explanation. However, at this time, over 150 years of experimentation and hundreds of thousands of experiments and sets of evidence point to this theory as the best explanation of evolution.
Natural Selection Example #1 Wolves eat moose! Wolves need to chase after moose quickly on Minnesota snow, without falling under. A wolf pup is born with slightly larger feet than all other wolves. He is a mutant. The large feet allow him to chase after moose quicker, without falling in snow (large feet act like snowshoes!!!). What does this mean for his survival? What does this mean for his reproduction? What will happen to the big foot trait in wolf populations over time?
Natural Selection Example #2 Dinosaurs had scales. Scales helped in protecting the animal. Some dinosaurs developed a mutation, longer scales. Scales were feathery and light. These light scales helped the dinosaur retain more heat. They also could be used to sweep food into the mouth.
What did these scales mean to the dinosaur s survival? What does that mean for their reproduction? What will happen to the light and feathery scales trait in the dinosaur population over time? What do you think eventually developed from these gradual changes?
Natural Selection Example #3 The Aye-Aye! This is a primate! YES related to US!!!! It is only found in Madagascar! It is an endangered species Write your example on the notebook page told to you by Sammler! Include the name of the organism(s) -- List three traits or notable characteristics about it that set it apart from others. -- Describe for each trait, why that adaptation evolved or was selected for in the aye-aye. -- Aye-ayes are considered bad luck by native people. So, they kill them when they see them. What is your hypothesis on the behavior of existing aye-ayes left in the wild? Explain why!