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2 of 7 The first wellknown theory of evolution:
3 of 7 Lamarck s theory of evolution: The Theory of Use/Disuse and Acquired Traits Jean-Baptiste Lamarck (1744-1829) was a French botanist who believed that species evolved because they inherited traits acquired through the over or under-use of body parts. How would this theory explain a giraffe s long neck? The short-necked ancestors of modern giraffes needed to reach the leaves on tall trees when food was scarce. Over their lifetimes these giraffes stretched their necks; a trait which was then passed on to their offspring.
The Inheritance of Acquired Traits 4 of 7 Lamarck believed that acquired traits could be inherited (ex. If you stretched your neck, dyed your hair, lost an arm, or had a large scar on your foot, your offspring will have those traits.) He also believed that all species had a tendency toward perfection that species were becoming more perfect with each generation.
Was Lamarck right??? 5 of 7
6 of 7 Darwin s theory of evolution by natural selection The British naturalist Charles Darwin (1809 1882) later suggested a more persuasive argument for evolution. Darwin proposed that evolution took place through natural selection. Darwin developed his theory of evolution after noticing close similarities between certain fossils and the adaptations of modern day animals he saw during his round-the-world voyage on the HMS Beagle.
Who was Charles Darwin? 7 of 7 Darwin's theory
He also used his own experience 8 of 7 Darwin bred pigeons. He noticed that he could breed pigeons to have certain traits (i.e., purple wings, a large wingspan, a certain song.) He called this artificial selection: when humans breed organisms to get specific traits in offspring. If HE could select traits in offspring of pigeons, maybe something in nature is doing this as well
How the giraffe got its neck 9 of 7 How does Darwin s theory explain a giraffe s long neck? Due to natural variation, the ancestors of modern giraffes would have had necks of different length. Giraffes with longer necks would have been able to reach more food than those with shorter necks. As a result, the long-necked giraffes were more likely to be healthy and live to produce more high-quality offspring. This, in turn, would increase the chances of their long-necked characteristic (an adaptation for the environment) being passed on to future generations.
Natural selection 10 of 7
11 of 7 Do organisms choose to adapt? NO! Because of natural variations, some are just more fit than others. The traits that made organisms more fit he called adaptations for the environment. Fitness: ability to survive and reproduce in a certain environment. Survival of the fittest refers to the fact that the organisms with the best adaptations (the most fit) will survive and reproduce better than the less fit organisms.
Galápagos finches In the Galápagos, Darwin noticed that different islands had different types of finches, with variations in their beaks. Some finches had strong and claw-like beaks, suitable for crushing seeds. They were more fit in environments with seeds. Other finches had thin and delicate beaks, suitable for picking insects from holes in the ground. They were more adapted to islands with many insects. Darwin thought all the finches could have evolved from one type of finch that came from the mainland. Natural variation meant that some finches had slightly different beaks. These finches would have been able to eat different types of food and avoid competition. They would therefore have survived and passed on their genes. 12 of 7
13 of 7 Adaptive radiation (one species adapting to many different environments)
14 of 7 Darwin s 4 parts of natural selection: 1) Variation exists within species 2) Organisms compete for natural resources 3) Organisms produce more offspring than what can survive 4) Environment selects organisms with beneficial trait: AKA- Natural Selection Survival of the fittest
15 of 7 Observable Evolution Evolution is difficult to observe directly, but there are some instances in which it can be observed today (happens quickly) As long as variation, overproduction, competition, natural selection and mutations occur, evolution will occur. Natural selection is observable in some populations! Pesticide Resistance Antibiotic Resistance
16 of 7 Pesticide Resistance Farmers use pesticides to eliminate insects. In a population of insects, some individuals will possess genetic immunity to certain chemicals This is variation in the population When the chemicals are applied, the individuals with genetic immunity will survive and reproduce, passing this resistance to the next generation of offspring. Overtime, more individuals are born with this immunity, rendering the pesticide useless
17 of 7 Antibiotic Resistance Antibiotics: drugs that fight bacterial infections Variation exists within populations of bacteria Some bacteria are genetically more resistant to the antibiotic than other bacteria If amount of antibiotic is too low OR the full course of antibiotics is not taken, only those least resistant will die. The resistant bacteria survive and reproduce Future applications of antibiotics, the population of bacteria become more and more resistant MRSA Methicillin-resistant Staphylococcus Aureus Caused by same staph bacteria resistant to most antibiotics used to treat regular staph infections