EVOLUTION How Species Change Over Many Years A Quick Review 1. When looking at rock layers, where are the oldest rocks/fossils located? 2. What type of rock consists of fossils? GOAL To define evolution and the 4 ideas associated with the theory Evolution Species A group of similar organisms that can interbreed to make fertile offspring Ex: All lions mate with one another – Lions + Tigers = infertile Ligers or Tiglons Evolution Evolution A change in a species over time Evolution Evolution How has man changed over time? Evolution Lamarck’s Theory Theory of use & disuse An organism gets a new organ if it needs it Use it more & it will grow bigger New organ is passed to offspring What do you think about the validity of Lamarck’s Theory? Give an example Evolution Darwin’s Theory Theory of natural selection Better explanation of evolution The survival & reproduction of the organisms best adapted to their surroundings Parts of the Theory of Natural Selection Part One: Survival of the Fittest Organisms overproduce offspring Organisms that are better competitors or more fit, will survive Ex: Survival of the Fittest Dandelions produce many seeds This ensures some will live- others will not be able to find enough food & sunlight Ex: Survival of the Fittest Tadpoles- many hatch at once Fierce competition- stronger, faster ones will find food faster & outrun enemies Parts of the Theory of Natural Selection Part Two: Variation and Adaptation Offspring that survive have structures or behaviors that make it better “adapted” to its environment Certain differences or variations help some to out-compete others – Even within a species – Ex: Finch Beaks Variations in Finch Beaks Variations in Beaks and Feet Parts of the Theory of Natural Selection Part Two: Variation and Adaptation Variation= small differences within one structure of a species that make an organism more fit Adaptation= changes in structures or behaviors that make an organism more fit Variation & Adaptation Example How would a variation in polar bear coats help certain polar bears to have greater fitness? – There are variations in polar bear coats – Some polar bears have thicker coats of fur than others= better protection to cold – They are more likely to survive- this adaptation to their surroundings makes them a better competitor Variation & Adaptation Example What happens to the fitness of a thick coated polar bear if the environment become warmer? Which type of polar bear has the better variation in coat? “The fittest that survive may change with their surroundings” Parts of the Theory of Natural Selection Part Three: Reproduction Individuals that are more fit: – Survive longer – Reproduce more – Pass on the beneficial traits or differences What causes evolution? Causes of Evolution Mutations or natural accidental mistakes in the animal’s DNA What causes evolution? Causes of Evolution Negative Mutation: Organism dies because it can’t compete (extinction) Positive Mutation: Organism becomes a better competitorincreases survival & reproductive chances Extinction Extinction Occurs when many small adaptations occur over time (or negative mutations) Those with new adaptations outcompete older “versions” of the species Assessment A hummingbird’s beak, giraffe’s neck & vampire bat’s teeth all help them to do what better? What are adaptations- how do they affect the organism? Evidence Supporting Evolution Evolutionary Evidence 1. Fossil Record- documents the change in organisms over billions of years Fossil Evidence Evidence Supporting Evolution Evolutionary Evidence 2. Anatomical Evidence- similar body structures – Homologous Structures= similar body parts that evolve suggest common ancestry Homologous structures What similarities do you see among the structures in the diagrams below? What do these homologous structures indicate? Homologous Structures Evidence Supporting Evolution Evolutionary Evidence 3. Embryological Evidencesimilarities in the embryos of very different organisms Evidence Supporting Evolution Evolutionary Evidence 4. Chemical and Molecular Evidence – The more similar the DNA code, the more closely related two organisms are DNA Homology Peppered Moth Scenario The Peppered Moth has been forced to evolve based on pollution from factories. Nowhere to Hide Peppered Moth Scenario Which moth ended up being more “fit” or a better survivor or competitor? Why? Websites “Becoming Human” interactive documentary Assessment A change in the future that may affect the evolution of living things is global warming How might global warming affect evolution? Why?