The Theory of Evolution

1. The Theory of Evolution 10/11/11

2. MA Frameworks • 3.3 Explain how mutations in the DNA sequence of a gene may or may not result in phenotypic change in an organism. Explain how mutations in gametes may result in phenotypic changes in offspring.

3. MA Frameworks 5. Evolution and Biodiversity • Central Concepts: Evolution is the result of genetic changes that occur in constantly changing environments. Over many generations, changes in the genetic make-up of populations may affect biodiversity through speciation and extinction. • 5.1 Explain how evolution is demonstrated by evidence from the fossil record, comparative anatomy, genetics, molecular biology, and examples of natural selection.

4. MA Frameworks 5. Evolution and Biodiversity • 5.2 Describe species as reproductively distinct groups of organisms. Recognize that species are further classified into a hierarchical taxonomic system (kingdom, phylum, class, order, family, genus, species) based on morphological, behavioral, and molecular similarities. Describe the role that geographic isolation can play in speciation. • 5.3 Explain how evolution through natural selection can result in changes in biodiversity through the increase or decrease of genetic diversity within a population.

5. What is Evolution? • Change over time • The process by which modern organisms descended from ancient organisms • Theory: A well supported testable explanation of phenomena that have occurred in the natural world

6. Charles Darwin 1809-1882 • Born in England (Same day as Abe Lincoln) • Traveled around world on ship – Beagle • Collected evidence and made observations that he used to develop ideas that became today’s Theory of Evolution

7. Key Questions • Where did the huge amount of biodiversity on the Earth come from? • Why are organisms so well suited to the environment that they inhabit?

8. Darwin & the Galapagos Islands • Group of small islands located off South America • Have very different climates, but close together • Observed that characteristics of plants and animals varied among different islands • Began to wonder – could these different animals have come from a common ancestor? Could they have once been members of the same species?

9. Darwin & the Galapagos Islands

10. Darwin’s Influences • Around the same time, scientists gained greater understanding of Earth’s changes over time, population growth, and developed primitive Evolution ideas

11. Darwin’s Influences • James Hutton: Showed that the Earth was far older than a few thousand years • Charles Lyell: Explained the geologic features of Earth shaped over very long time. • J.B. Lamarck: Observed that organisms adapted to environment. • Incorrectly proposed that use and disuse of body part will influence whether passed down to next generation

12. Darwin’s Influences: Pop. Growth • Thomas Malthus: Suggested that if human population continued to growrapidly, soonerorlatertherewould not be enoughlivingspaceor food for everyone • Darwin applied this idea to otherorganisms

13. The Origin of Species, 1859 • The book that contained Darwin’s ideas about Evolution • Proposed a mechanism for evolution that he called Natural Selection Provided evidence that Evolution has been happening for millions of years

14. Early Evolution Controversy • Responding to the Bishop of Oxford, Samuel Wilberforce's question whether he traced his descent from an ape on his mother's or his father's side, Thomas Huxley said: • If then, said I, the question is put to me would I rather have a miserable ape for a grandfather or a man highly endowed by nature and possessing great means and influence and yet who employs those faculties for the mere purpose of introducing ridicule into a grave scientific discussion—I unhesitatingly affirm my preference for the ape.

15. Natural Selection • Premise that organisms stuck in struggle for existence- food, shelter, resources, etc. • Success depends on ability of an organism to survive and reproduce in its environment – known as Fitness • Fitness results from adaptations – inherited characteristic that increases organisms chance of survival

18. Natural Selection • Is survival of the fittest when the traits being selected for (whether a trait is good or not) is being determined by fitness in an environment • Results in changes in characteristics of population. • Increases a species fitness over time

19. Descent with Modification • Idea of Darwin’s suggesting that every living species as descended, with changes, from other species over time. • Principle of Common Descent: All species, living and extinct, were derived from common ancestors.

20. Evidence for Evolution • Fossil Record: See change in organism structures over time • Similar organisms living in similar environments in places very far apart • Homologous body structures: Structures that changed over time to suit the needs of different species, but that originated as one type of structure (fish fin)

21. Homologous Structures

22. Vestigial organs • Structures in organisms that may have served purpose in ancestral species, but no longer have function in current organism • Ex. Human Tailbone

23. More Evidence: Embryology • The very early stages of development for a wide variety of organisms look the same • Similar cells grow and divide in very similar ways in many species