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1. EVOLUTION as a Unifying Theory images.fws.gov

2. Darwin’s Theory of Evolution Other Biological Theories: Cell Homeostasis Gene Ecosystem Recall the difference between a theory & a Scientific Theory Supported by a broad range of observations, experiments & data from a variety of disciplines Speculative Idea

3. “Nothing in biology makes sense except in the light of evolution.”--Theodosius Dobzhansky, 1973

4. WHAT IS EVOLUTION? • Evolution is the unifying theory of biology A. What does evolutionary theory explain? • Diversity of life • Traces all living thing through lines of common ancestry

5. Tree of Life Project • htpp://tolweb. org/tree

7. 2. Differences and similarities among organisms Homologous structures suggest common ancestry

8. 3. The characteristics of organisms, both useful and non-useful Vestigial structures

9. B. What is evolution? 1. In a broad sense, evolution simply means change. -comes from the latin word ‘evolvere’ “To unfold or unroll” -to reveal hidden potentialities

10. 2. A process of descent with modification from common ancestors -descent is the cumulative transmission of genetic information across generations -modification is the alteration in the composition of genetic information -common ancestry is that all of life shares a history of common ancestors

11. Humans have always been interested in the Origin of Species • Aristotle (300s BC) – Greek Philosopher • ScalaNaturae or the Great Chain of Being • 1. Progression from most complex to least complex • -every organism is ordered in relation to man • 2. Organisms are unchanging since they were created in perfect form • -change would imply imperfection in the original creation • 3. Impossible for new forms to have arisen since creation or existing forms to have gone extinct.

12. History of Evolutionary Thought:The age of the Earth and Living Things • Modern geologists • Earth is > 4 billion years old • Life began 3.8 BYA • 1800s • Earth was 1000s of years old • Species existed in current form and NEVER changed Killer whale & ancestor with vestigial limbs

13. History of Evolutionary Thought • Early Natural Science focused on cataloging and describing species • Carolus Linnaeus (1700s) • Taxonomist • Binomial nomenclature; • Believed in “fixity of species, scala naturae, type specimen • Consistent with Judeo-Christian teachings, Plato & Aristotle • published SystemaNaturae in 1735

14. History of Evolutionary Thought • Count Buffon (1700s) Georges-Louis Leclerc • Naturalist • 44-volume natural history of all plants & animals—Histoire Naturelle 1749 • Provided evidence for descent with modification • Suggested environmental influences, migration, geographic isolation & struggle for existence • Closely related species (horse and donkey) might share common ancestry • Still hesitant

15. History of Evolutionary Thought:Cuvier & Catastrophism • Baron Georges Cuvier (1769-1832) • Comparative Anatomy • Founder of Paleontology • Study of fossils • Staunch supporter of creation and fixity • Problematic based on fossil record • Catastrophism (Wrong!) • Periods of catastrophic events occurred, after which repopulation of surviving species took place, giving appearance of change over time Mastadon- extinct mammal

16. History of Evolutionary Thought • Erasmus Darwin (1731-1802) • Charles’ grandfather, physician & naturalist • Writings on botany & zoology suggested common descent • Changes during development, artificial selection, vestigial organs • Offered no mechanism by which evolution could occur but believed that species evolved through lines of common descent

17. History of Evolutionary Thought:Lamarck & Acquired Characteristics • Jean- Baptiste de Lamarck (1744-1829) PhilosophieZoologique in 1809 • Invertebrate Biologist • 1st biologist to think adaptive evolution occurs & linked adaptation to environment • More complex organisms descend from simpler ones • But mistakenly said this was a natural force • Inheritance of acquired characteristics (Ooops!) • Environment can bring about inherited change

18. History of Evolutionary Thought • Principles of Geology-Lyell in 1834 • 1. Calculated extinction rates from fossil record • -extinction rates were relatively constant from layer to layer • -why aren’t all species found today not represented in oldest strata? • 2. Periods of major extinctions correlated with periods of environmental change • -process of “selection” was obviously eliminating species that were unfit for new environmental conditions • Uniformitarianism-Hutton in 1785 • Geological processes operating in the past are the same as those operating today • Earth is very old and has undergone a long history of geological change

19. Darwin & Evolution Proposed mechanism of evolution: Natural Selection

21. History of Evolutionary Thought:Charles Darwin (1809-1882) • Born February 12th • Trained: • Surgeon • Naturalist • Theologian • Set sail British naval vessel • HMS Beagle • Captain Robert Fitzroy • Expand Navy’s knowledge of foreign natural resources • Captain Fitzroy hoped Darwin would find evidence to support biblical creation

22. History of Evolutionary Thought:Charles Darwin: Voyage of the Beagle

23. Darwin’s Theory of Evolution:Geology & Fossils James Hutton- Extreme geological changes can be accounted for by slow, natural processes Charles Lyell’s Principle of Geology: Supported Hutton’s proposed uniformitarianism: - slow changes occur at uniform rate

24. Darwin’s Theory of Evolution:Geology & Fossils • Earth is OLD • Observed geological features • Collected fossils • Made him realize that there was enough time for descent with modification to occur Extant Pygmy Armadillo of South America

25. 1. Observations made in the Galápagos Islands • -mockingbirds from • different islands looked • like different species • -same was true for • tortoises and finches • -bills were adapted to fit • well with foods available

26. Darwin’s Theory of Evolution:Biogeography • Biogeography- • Study of range and geographic distribution of life forms • South America & the Galapagos Islands • Descent with modification from common ancestors

27. Ancestral finch Molecular phylogeny of Darwin’s Finches (Petren et al. 2005)

28. History of Evolutionary Thought • IV. Alfred Russel Wallace (1823-1913)

29. The Wallace Line • Separation of Asian and Australian flora and fauna in as little at 15 miles!

30. Darwin’s Theory of Evolution: • After Beagle voyage, Darwin reflected until 1859 • On the Origin of Species by Means of Natural Selection • Adaptations occur over time • Needed a mechanism to describe… • Charles Darwin & Alfred Russel Wallace proposed NATURAL SELECTION • Process by which evolutionary change occurs • 1. Individuals within a species are variable • 2. Certain of these variants are passed to offspring • 3. In a population, many MORE individuals are produced than the environment can support • 4. Differential survival and reproduction = NATURALLY SELECTED • Only favorable variants (to environment) survive to reproduce • These variants increase in frequency in future generations

31. 1 & 2. Populations have heritable variationsOrganisms Have Variations • Vary • Functionally • Physically • Behaviorally • Variation is • Random • Good • Bad • Now know genes cause variations Variation in Human Population

32. 3. In a population, many MORE individuals are produced than the environment can supportOrganisms Struggle to Exist • Thomas Malthus • Socioeconomist • Death & famine inevitable because human populations increase faster than supply of food • Essay on the Principle of Population (1798) • Darwin applied this to all species

33. 4. Some individuals have adaptive characteristics that enable them to survive & reproduce better than othersOrganisms Differ in Fitness • Fitness • Survival & Reproductive Success of an individual relative to other members of a population • Most fit = most resources = most likely to survive to reproduce and leave its genes (traits) in the next generation • These traits are favored by NATURAL SELECTION

34. Adaptations are the products of natural selection • Adaptation • Any trait that helps an organism to be more suited for its environment Would you eat this frog? images.fws.gov

35. Natural Selection vs. Artificial Selection • Artificial Selection • Breeder chooses traits to perpetuate by choosing parents • Canis lupus vs. Canis lupus familiaris • Also, cabbages • As example…

36. Darwin’s views were not accepted until the intellectual and scientific revolution of mid 1800s • Darwin • Species change over time  Evolution • Living things share common characteristics because share common ancestor • Species adapt to specific habitats and ways of life

37. Lamarck’s view Species arise independently Complexity increases through time scala naturae Darwin’s view Species arise through common ancestry Complexity increases through time Descent with modification

38. Evidence for Evolution:Fossil Record • Fossil record represents history of life on Earth • Fossils < 10,000 years old • Ice, sediments, sap (amber), petrification, impressions in shale • Simple  complex • Transitional Fossils • Links between groups • Most famous examples: • Archaeopteryx • Tiktaalik Archaeopteryx

39. Tiktaalik roseae A “Fishapod” Late Devonian 370 MYA Daeschler et al. Nature 2006

40. Evidence for Evolution:Biogeographical Evidence • Biogeography • Study of range & distribution of plants and animals throughout the world • Likely species involved in one locale and spread out • Marsupials in Australia and New Zealand; mammals on other continents

41. Evidence for Evolution:Anatomical Evidence • Vertebrate forelimbs • Flight, swimming, running, climbing, swinging, weight-bearing • All have same bones • Organized similarly • Suggest common ancestor • Homologous structures • Common embryonic origin from common ancestors

42. Evidence for Evolution:Anatomical Evidence • Vestigial Structures • Features that are fully developed in ancestor but reduced/lack function in descendants Ambulocetus, ancestor to whales

43. Evidence for Evolution:Anatomical Evidence • Embryologic Development • Vertebrates share through common ancestor: • Dorsal Hollow Nerve Cord • Notochord • Post-anal tail • Pharyngeal gill pouches/slits • Iodine Binding Structure

44. Evidence for Evolution:Biochemical Evidence • DNA • ATP • Genetic code

45. Sources • PBS Evolution website • http://www.pbs.org/wgbh/evolution/Courses • Courses at Clemson: • Biol 210: Evolution & Creation • Biosc 408: Comparative Vertebrate Morphology • Biosc 303: Vertebrate Biology • Biosc 335: Evolutionary Biology • Biosc 446: Evolution of Human Behavior • NPR podcasts • Books of interests if you are trying to find the middle ground- • Finding Darwin’s God • (Ken Miller) • The Language of God: A Scientist Presents Evidence for Belief • (Frances Collins) • Famous evolutionary biologists and writers • Ernst Mayr • Jared Diamond • Stephen J. Gould • Richard Dawkins