Introduction to Evolution What is Evolution?? It is a theory explaining the process by which modern organisms have descended from ancient organisms. Charles Robert Darwin (1809 – 1882) • An Englishman • Sailed on the HMS Beagle for 5 years • Visited many places including The Galapagos Islands • Observed birds – Finches • Attempted to explain evolution • Author of “On The Origin of Species” • 201 years old this year The Galapagos Islands Watch Video: Galapagos ENJOY!! Before Darwin • Jean Baptiste de Lamarck – 3 assumptions on adaptation • A desire to change • Use and disuse • Passing on acquired traits A Desire to Change • Naturally want to be better – Example: Bird’s ancestor wanted to fly, therefore they developed wings. Use and Disuse • Organs could change in size depending on the amount of usage. • Vestigial structures Passing on Acquired Traits • Acquired: to gain ownership • Trait: characteristic • Acquired trait: a characteristic you gained after you were born – A woman dyes her hair purple, her baby will be born with purple hair. – A swimming champion will produce swimming champion babies. Charles Darwin • His theory of evolution was influenced by 3 key people/group: 1. Lyell (Geological influences) 2. Farmers (Selective breeding) 3. Malthus (Overpopulation) Lyell’s Idea • Earth was very old • It changed over time • Evolution took MANY years to happen. • It took MANY years for millions of species to evolve from a common ancestor Farmers • Artificial Selection • Farmers only chose the traits that benefited them • Darwin: Perhaps nature (environment) also chose the trait that best suited for survival/reproduction Malthus • • • • Population Controls He noticed that Birth rate > Death rate Not possible due to lack of space, food Growth Prevention: Famine, disease, war Who gets to stay alive? The FIT ones (Survival of the Fittest) Genetic Variations in Species • Individuals of the same species are different from each other. • Variations: – Height, weight, hair colour, skin colour, eye lids • Variations that are: – Well-suitable for the environment survives – Not well-suitable for the environment dies Darwin’s Survival of the Fittest • Individuals whose characteristics are wellsuited to their environment survive and reproduce. FIT • Individuals whose characteristics are not well-suited to their environment either die or leave fewer offspring LESS-FIT Going back to Malthus’ idea: The fact that less-fit individuals of a species don’t survive helps prevent the species from covering the Earth. Peppered Moths Case • Where: England • When: Early 1800s Around Industrial Revolution Period Before Revolution After Revolution Oak trees had light brown bark Oak trees bark got stained dark brown Most moths were light brown Most moths were dark brown What happened? Before the revolution Clean tree bark After the revolution Stained tree bark Kettlewell’s Confirmation Area A: Normal coloured trees Area B: Dark coloured trees His Hypothesis?? His observations?? Kettlewell’s Confirmation Light coloured area light colour moths survived better Dark coloured area dark colour moths survived better Conclusion: In each environment the moths that were better camouflaged had the higher survival rate A way to hide oneself In conclusion What changed the moths? The nature did, that’s why it’s called NATURAL SELECTION. "Evolution is the result of genetic changes that occur in constantly changing environments."