Presentation on theme: "Darwin & Natural Selection"— Presentation transcript:
1 Darwin & Natural Selection Unit 6: EvolutionChapter 15
2 Learning Goals 1. Define "Evolution" & "Natural Selection". 2. Describe the 4 steps of Natural Selection, giving an example of each.3. Explain the importance of "Variation".4. Does Natural Selection act on an organism phenotype or genotoype? Explain!5. List the 5 evidences that support the Theory of Evolution.
3 Theory of Evolution Evolution: The process of change over time Specifically, a change in the frequency of a gene or allele in a population over time
4 Charles Darwin Father of Evolution Proposed a mechanism for evolution, natural selectionDarwin went on a 5-year trip around the world on the ship, the HMS BeagleAs the ship’s naturalist, he made observations of organisms in South America and the Galapagos IslandsWrote a book, “Origin of the Species”
14 Why is Variation Important? Because the environment changes.The more variation within a species, the more likely it will surviveEX: If everyone is the same, they are all vulnerable to the same environmental changes or diseasesThe more variation of types of species in an habitat, the more likely at least some will surviveEX: Dinosaurs replaced by mammals
15 Which community has a better chance of surviving a natural disaster? Community ACommunity B
16 3. Competition Individuals COMPETE for limited resources: Food, water, space, matesNatural selection occurs through “Survival of the fittest”Fitness: the ability to survive and reproduceNot all individuals survive to adulthood
17 4. SelectionThe individuals with the best traits / adaptations will survive and have the opportunity to pass on it’s traits to offspring.Natural selection acts on the phenotype (physical appearance), not the genotype (genetic makeup)Ex: When a predator finds its prey, it is due to the prey’s physical characteristics, like color or slow speed, not the alleles (BB, Bb)
18 Individuals with traits that are not well suited to their environment either die or leave few offspring.Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.
36 Biochemical EvidenceBiochemistry: DNA with more similar sequences suggest species are more closely relatedEX: Humans and chimpanzees share more than 98% of identical DNA sequences
37 Learning Goals 1. Define "Evolution" & "Natural Selection". 2. Describe the 4 steps of Natural Selection, giving an example of each.3. Explain the importance of "Variation".4. Does Natural Selection act on an organism phenotype or genotoype? Explain!5. List the 5 evidences that support the Theory of Evolution.