What does the phrase Only the Strong Survive mean to you?? Essential Questions: How are we Here? What caused so many different living things to populate Earth? Why do Living things become extinct? 1
A. Evolution: Genetic change over Time Genetic Change= Mutation Time: Age of Earth= 4.6 Billion Years Ago B. History of Evolutionary Theory 1. Greek Philosophers: Scale of Nature: Aristotle Natural things are perfect the way they were created no need for perfect things to change. 2. Creationism: Modern religions explanation for "Why we are here!" "Adam and Eve" If god or gods are perfect and they created Earth and life...it too must be perfect...then why would it need to change? 3. Influences that changed the world outlook Fossil Record: Collection of fossils of extinct species that do not resemble life on Earth today! (Or did they) Modern Geology: Hutton and Lyell: Age of the Earth: Pace of Geologic change is very slow...needs a lot of time Thomas Malthus: Economist Earth has a Carrying Capacity not enough resources for the growing population Social competition for limited resources Might cause spread of disease and war between the haves and the have nots 2
4. Evolution A. Catastrophism: Bonnet and Cuvier Life before humans was wiped out by a series of global catastrophes Easily intermixed with our religious past! (Think Noah and his Ark!) B. Gradualism: Constant slow change over a long period of time 1. Jon Baptiste LaMarck: First theory on the process of evolution "Passing Down of Acquired Characteristics" or "Use v Dis use" A. All organisms strive to improve (Use v disuse) B. Disused organs will shrink and disappear while the used organs will grow and become stronger! (Acquired characteristics) C. Pass down these characteristics to our offspring Wrong!!!! but a great first step towards figuring out the process of evolution Clipping Dog Ears 3
15.3: Darwin presents his case "Descent with Modification" A Darwinian View of Life The Darwinian Revolution On the Origin of Species by Means of Natural Selection (1859) Charles Darwin A British Naturalist (trying to avoid his Dad's pressure to become a Doctor or a Lawyer) Voyage on the HMS Beagle Collecting all kinds of natural specimens, living and extinct and begins to ask the question... How Did they Get here? Galapagos islands: An ideal evolutionary environment! Volcanic Islands= Never part of Pangea When they were created, no living things Far enough from Mainland South America that living things struggle to migrate there. Geographic Isolation Stops mixing of genes Notices variation among animals... Especially the Finches and the turtles 4
Beak variation in Galapagos Finches Why would the same bird species require different beaks? What is the function of a Beak? B. Darwin's Theory of Evolution "Natural selection" or "Survival of the Fittest" 1. Variation exists within a population 2. Some of these variations will make one organism stronger or more fit than another! (Fitness) 3. There is competition for limited resources...thanks Malthus!!!! 4. The organism with the greater fitness will survive to reproduce and therefore pass on that variation (Survival of the Fittest) Nature (food, environmental conditions, geologic changes, climate variation) will select which variation survives) What if People are in charge of the selection? Artificial Selection Knows nothing about genetics: Gregor Mendel doesn't publish his paper on inheritance for another 6 years, But we do!!!!! 5
Short Neck Giraffe!!!! (Weird, Right?) Long Neck giraffe!!!!! (Now that is more like it) How would Darwin explain these giraffes! Arctic Hare! Which came first? White Rabbits or Snow? 6
Shell Variations in the Galapagos Tortoise 7
Evidence of Evolution: 1. The Fossil record shows continuous change in living things that are related in structure and function (both extinct and living/extant) Trilobite Fossil Evidence of the Fish to Amphibian Evolution 8
2. Geographic Distribution of living species: Animals separated by thousands of miles but living in similar environmental conditions often showed similar variations to those environments Convergent evolution: when two unrelated organisms have evolved similar adaptations to the same climate or environmental conditions Chupa cabra???? 3. Homologous structures How are these things similar? Different? turtle Alligator Bird whale Bats Here is how we are similar!!! Me! 9
4. Embryological Similarities 5. DNA Evidence Central dogma We share 66% of our genetic information with an earthworm Your long lost cousin!!!!! Transgenic organisms 10
Examples of genetic evolution include: Pesticide Resistance and Antibiotic Resistant Strains of Bacteria (MRSA) Anti viral Resistant HIV 11
Quiz Define these terms: Evolution: Fossil: What is the common name for LaMarck's theory of Evolution? What are the three main points of his theory? 1. 2. 3. What are the four main points of Darwin's theory? 1. 2. 3. 4. How is his theory different from LaMarck's? 12