2Evolution – The process by which modern organisms have descended from ancient organisms.
3Evolution – The process by which modern organisms have descended from ancient organisms.
4Adaptation – A trait that helps an organism be better suited to its environment. ex) a ducks webbed feet
5Adaptation – A trait that helps an organism be better suited to its environment. ex) an arctic fox’s heavy fur coat
6Fitness – The physical traits and behaviours that better enable organisms to survive and reproduce in their own environment.What makes these polar bears fit to live in the arctic?
7What makes this fenec fox fit to survive in the extremes of the Sahara Desert?
8EXPLANATIONS FOR EVOLUTION Around 1800, scientists began to realize that living things changed over time.
9Jean Baptiste de Lamarck Lamarck is considered to be the first person to develop a theory of how evolution occurred.He is credited with encouraging future scientists to examine how evolution occurred.
10Lamarck’s Big Ideas Desire to change Law of use and disuse Inheritance of acquired characteristics
11Lamarck also believed body parts could change shape or size depending on needs. Lamarck explained the long neck of a giraffe by saying if it stretched its neck for leaves a “nervous fluid” would flow into its neck and make it longer. Its offspring would inherit the longer neck, and continued stretching would make it longer still over several generations. Meanwhile organs that organisms stopped using would shrink.
12Lamarck believed in the inheritance of acquired characteristics. Consider the ears and tails of Doberman Pinschers.
13Charles DarwinEnglish naturalisttravelled around the world on the H.M.S. Beagle observing plant and animal lifethe trip took over 5 years
14Further Influences on Darwin: Charles Lyell (a rock star - geologist)he argued the Earth was very old while most believed earth to be a few thousand years oldthis meant common descent could have had enough time to occur
15Further Influences on Darwin: FarmersDarwin knew farmers altered their stocks with breeding programs (artificial selection)with a.s. humans ensure only animals with desirable traits are allowed to breedDarwin felt nature must have a similar process only allowing the best suited to the environment to survive
16Further Influences on Darwin: Thomas Malthushe realized babies were being born faster than people were dyinghe felt only famine, disease and war would prevent endless human population growthDarwin extended this to plants & animals as he realized many individuals of each species die and few raise offspring. The question was what determined who survived and reproduced?
23Galapagos Tortoises – These were important to Darwin developing his Theory of Evolution.
24The islands were once home to 15 different sub-species The islands were once home to 15 different sub-species. 11 of these remain today. One sub-species only has one individual.Lonesome George – the last of his kind
25Five sub-species are found on Isabela and one each on Santiago, Pinzon, Santa Cruz, Española and San Cristobal. Lonesome George is from Pinta but lives on San Cristobal today in a breeding facility.
26The main differences between sub-species is the length of their limbs and necks and the shape of their shells.
27Galapagos FinchesThe 13 species of Galapagos Finches were also important to Darwin developing his Theory of Evolution.
28Darwin decided that species change over time in 1859, he published his famous book that describes his theory of evolution
29a key part of the theory was the idea of Common Descent a key part of the theory was the idea of Common Descent. It argued all species have evolved from one common ancestor.an evolutionary tree, from one of Darwin’s notebooks
30Darwin’s Theory of Natural Selection states: more organisms are born than survive- the environment can’t support them all
31Darwin’s Theory of Natural Selection states: organisms vary within a species- no two individuals are exactly alike
32Darwin’s Theory of Natural Selection states: survival of the fittestorganisms with favourable variations survive and reproducethe individuals with characteristics not well suited to their environment either die or leave fewer offspringin this way, favourable variations are passed from generation to generation
33Darwin’s Theory of Natural Selection states: a population that is adapted to its environment will result
35In 1858 Alfred Wallace wrote to Charles Darwin about his ideas of evolution. His work also describes the theory of natural selection.Wallace and Darwin co-published a paper on evolutionary theory and are considered the co-discoverers of the Theory of Evolution.Each man gave the other as much credit as possible.