1. The Modern Synthesis: Evolution and Genetics

2. Charles Darwin - Born in Shrewsbury, England on February 12, 1809 - Born into a wealthy family as the 5 th of 6 children - Grandfather, Erasmus Darwin, had proposed that all life came from a single organism, “the Great First Cause” - Darwin was encouraged to become a doctor, but was fascinated with the natural world

3. The Voyage of the Beagle December 27, 1831, he joins the HMS Beagle as a naturalist on a five year voyage The ship’s mission was to map the coast of South America for Britain As a naturalist, Darwin was to observe and collect specimens

4. How did he begin to craft his theory of evolution?

5. Observations in South America In Argentina, Darwin uncovered fossils of the Megatherium and Glyptodon These fossils looked like giant sloths and armadillos The fossils were found in the same geological range as these modern animals Fossils of marine organisms also found in the Andes Mountains

6. Island chain 1000 km west of Ecuador Discovered many new species with many similarities to species found on South America No native amphibians or large land mammals – why? Observations in the Galapagos Islands

7. Marine Iguana: – Closely resembles iguanas from the South American Mainland – Is the only known lizard able to dive and forage in water Observations in the Galapagos Islands

8. Giant land tortoises – At least five unique species were found on different islands Observations in the Galapagos Islands

9. Darwin at first thought they were one species with variation 13 species with distinct characteristics Their beaks show variation in shape and size – Why? Darwin’s Finches

10. After leaving the Beagle in 1836, Darwin spent more than 20 years gathering evidence on evolution He knew that his theories would be controversial By the time he presented his theory, Darwin was able to not only explain that evolution had happened, but also how it occurred…mostly Forming the Theory

11. By 1844 Darwin had prepared an essay on his theory of Evolution, but did not publish it 1858 - received a letter from Alfred Russell Wallace, who had also concluded that evolution must be true This pressure led Darwin to publish his theory as On the Origin of Species in 1859 On the Origin of Species

12. Backlash

13. What Darwin didn’t know… How do organisms inherit traits? How are traits passed on from one generation to the next? DNA

14. We looked at evidence for evolution Do you remember what the evidence was? What do you remember about heredity? What do you remember?

15. Monk who bred pea plants He focused on how traits were passed from one generation to the next Early studies in genetics Mendelian Genetics

16. Much later, we would realize that the theories of genetics and evolution are closely linked Genetics can help explain evolution Unifying Theories

17. Modern Evolutionary Synthesis: the modern theory of evolution that takes into account all branches of biology This includes genetics It also includes the plate tectonic theory we’ve looked at Modern Evolutionary Synthesis

18. Darwin 2.0 For Darwin, evolution was the changing of inherited traits in a species over time We now consider evolution as changes in the gene pool of a species over time. Gene Pool: the complete set of all gene variations within a species or population

19. Genes code for different traits Individuals have different traits because they have different combinations of gene variations Genetic Variations and Selection

20. VERY IMPORTANT! Evolution acts on genes!

21. At the end of meiosis, a sex cell has only one set of chromosomes. Reproduction leads to variety: new combinations of genes (both from mother and father) – Crossover events lead to even more variety: genes get shuffled around between homologues Remember Meiosis?

22. Sexual reproduction and crossing over have the same purpose: – Introduce new varieties of genetic combinations Genetic Variation

23. Mutation events happen in many different ways A gene may be lost, switched, or modified An individual can also gain duplicates of genes Mutations

24. Remember! Mutations can be neutral, beneficial or harmful!

25. Mutations can affect an individuals chances of survival Missing genes is often harmful Having extra copies of genes might be useful – Eg: human populations that eat a lot of starch have two copies of genes for starch proteins, make double the protein Mutations and Survival

26. This is an important type of mutation A mutation to a gene can often be harmful, even fatal But having an extra copy means that if that gene mutates, there is still another copy to make sure the cell functions properly New and novel mutations may now occur – Eg: rod and cone cells in eyes Type of Mutations: Gene Duplication

27. Duplication Mutations: – Often neutral – Do not immediately benefit the individual – Source of new genetic material with potential to evolve into new genes Types of Mutations: Gene Duplication

28. The mammalian forearms suggested a common ancestor These homologous features arise because of homologous genes Homologous Genes

29. Homologous genes share a common ancestor, but have mutated over time The more closely related two species are, the more similar their homologous genes will be Homologous Genes

30. Pseudogene: A vestigial gene that has undergone mutations and no longer serves a useful purpose Eg: Dolphins have 1000 genes for olfactory (smell) receptors, but only use 200 of them – Why? Pseudogenes

31. Dolphins have 1000 genes for olfactory (smell) receptors, but only use 200 of them Smell receptors detect airborne chemicals, so are of no use to dolphins Pseudogenes

32. Pg 313 #5, 6 Pg 320 #34, 35, 36, 54 Homework