E volution Thursday 10/24/13

1. Evolution Thursday 10/24/13 • Charles Darwin • influences on his thinking // decent with modification • evolution by natural selection • overview • Evidence of Evolution • fossil record • biogeography • comparative anatomy // embryology • molecular biology • studies demonstrating evolution

2. Evolution: • change • change in • change in • Charles Darwin – “father of evolution” proposed a mechanism of change over time…….

3. Historical Context • Prevailing thought prior to Darwin’s time: • Darwin was strongly influenced by the writings of geologist Charles Lyell • Lyell proposed • earth was at • Darwin reasoned that: • IfEarth is • then subtle processes occurring

4. Historical Context • Malthus’“Essay on the Principle of Population”(published 1798) • Darwin was strongly influenced by the Malthus’ writings and reasoned that: • all though all organism • only a limited number

5. The Voyage of the Beagle • In December 1831, Darwin left Great Britain on the HMS Beagle to explore the world….. Darwin’s voyage on HMS Beagle 1831-1836 see fig 27.1

6. Darwin was intrigued by: • Fossil beds of South America • Species composition • Plants and animals on • Yet, species in similar habitats • Similar species

7. Theory of Evolution by Natural Selection: Based on observations during his travels and subsequent research/experimentation, Darwin proposed a theory to explain how and why populations change over time: Wrote manuscript – “Origin of Species” in 1844 – not published until 1858 w/in a decade - widely accept that evolution occurs Fig 27.3

8. Descent with Modification Darwin made two main points in The Origin of Species: • Organisms inhabiting Earth today • not all individuals • individuals best fit • population becomes

9. The result of natural selection is evolutionary adaptation: (b) A Trinidad tree mantid that mimics dead leaves (a) A flower mantid in Malaysia (c) A leaf mantid in Costa Rica

10. Evolution: • Darwin did not invent the idea of evolution; he agreed with many philosophers and naturalists that diversity was produced by evolution • But scientists did not know how evolution occurred: prior to Darwin there • A predecessor to Darwin,

11. Adaptations / Evolution: • Lamarck’s theory of acquired characteristics • individuals passed on • better variations fig 27.2

12. Adaptations / Evolution: • Darwin’s theory • parents with • frequency of adaptive traits

13. Descent with modification: Think about “artificial selection” • In Nature -- NATURE DOES Figure 13.5

14. Evidence of Evolution • Grant’s work & the Darwin’s Finches

15. Rivers bring sediment to the ocean. Sedimentary rocks containing fossils form on the ocean floor. 1 Over time, additional strata are added, containing fossils from each time period. 2 3 As sea levels change and the seafloor is pushed upward, sedimentary rocks are exposed. Erosion by rivers reveals strata; deeper strata contain older fossils. Younger stratum with more recent fossils Older stratum with older fossils Fossils • preserved • often found in

16. The fossil record • the • testifies that present day South American armadillo extinct - found in fossil record

17. Fossil Record & Transitional species: • examples: • fish --> early tetrapod --> modern tetrapod (amphibians) • early whales --> modern whales

18. Biogeography • the study of the • suggested to Darwin that • organisms in • organisms on isolated islands Australia Koala Kangaroo

19. Comparative Anatomy see fig 27.7 • the comparison of • confirms that • Homologous characters • Analogous characters

20. Comparative Embryology • Comparative Embryology is the comparison of structures see fig 27.8 Comparative embryology of vertebrates supports evolutionary theory -

21. Molecular Biology • Evolutionary relationships among species • more closely related evolutionarily: • more distantly related evolutionarily: relative similarity between CytochromeC structure (protein used in ETC) fig 27.9

22. Evidence of Evolution • Example of microevolution: • Darwin’s finches - medium ground finch Peter and Rosemary Grant Researchers at Princeton, began studying the finches in the 70’s Geospiza fortis – Medium Ground Finch

23. Darwin’s finches South America • Grassquit colonized islands from SA 2.3 mya • Darwin observed on Beagle 1831-1836 Galapagos • noticed: different bills and diets

24. Darwin’s finches

25. Researchers captured, measured, weighed, and banded individuals Medium Ground Finch Variation in • Variation in

26. variation in • population of Over 20 months 84% disappeared before breeding

27. Selective pressure: • Typically • Number and type of seeds Tribulus seeds

28. Result: evolution of greater beak depth • mean beak depth of finches hatched in 1976: • mean beak depth of finches hatched in 1978: • fossils:

29. heritable character! Evidence of Evolution • Example of microevolution: change w/in a population over generations • variation in • larger bill - • smaller bill - • weather conditions • selective advantage • large-billed birds fig 22.12 see fig 27.11

30. Evolution of Pesticide- Resistant Insects • variation in population • differential survival • change in frequency of Note:

31. Evolution at level of POPULATION not individual! • insects had gene or did not have gene • w/ gene - • w/o gene - • change in • subsequent generations

32. Adaptations -- Individuals vs. Population: • populations adapt • variation in the • what is “adaptive” • individuals are adapted • individuals with

33. Evolution by Natural Selection: summary • historical thinking ripe for Darwin’s theory • evolution occurs at the • changes in frequency • constrained by ancestry • variety of evidence supports the theory of evolution • one mechanism • passing down • increase probability • KEY aspect of