Last day… overview of what the course will cover,

1. Last day… overview of what the course will cover, started discussing historical development of evolutionary thinking - idea of evolution had been debated, but generally rejected Buffon Erasmus Darwin Saint Hilaire Lamarck

2. Charles Darwin • provided evidence that evolution had occurred • first to develop a theory to explain how & why evolution happens - left him last day on voyage of the Beagle (1832-36) Glyptodon

3. 4 spp. of mockingbirds from Galapagos

4. What patterns of distribution would be expected if species are independently created (as opposed to what is expected if species are related by descent from a common ancestors)? a) very similar species will be expected in similar habitats even if on different continents b) species in very different habitats will be very different, even if the habitats are geographically close c) different species will be found on opposite sides of geographic barriers, even if the habitats are similar d) endemic species on islands will be closely similar to those of the nearest continent e) species will be found in environments that they are well adapted to

5. - influence of geological theories • Lyell: Uniformitarianism: geological patterns • created by presently observable forces, ancient • history of the earth Charles Lyell: 1797-1875

6. Started notebook (1837) to record ideas • Many facts suggested evolution, but • needed a theory... - must produce change - must account for adaptation - must explain speciation

7. Inspiration from Thomas Robert Malthus (1798) • population growth will always tend to • outrun food supply • - immediately suggested natural selection

8. Darwin’s insight in 1838 - quickly developed this into theory explaining how all living things evolved into their diverse forms "is the most powerful and the most comprehensive idea that has ever arisen on earth. It helps us understand our origins ... We are part of a total process, made of the same matter and operating by the same energy as the rest of the cosmos..." (Sir Julian Huxley) and then... silence

9. Delayed publishing - started outline 1842 • …until he received a paper in 1858 outlining natural selection Who mailed the paper to Darwin? a) Robert FitzRoy b) Thomas Henry Huxley c) Alfred Russell Wallace d) Sir Charles Lyell e) Samuel Wilberforce

10. Wallace’s paper stunned Darwin… Friends arranged for joint reading of papers atLinneanSociety - Darwin published ‘The Origin of Species’ in late 1859

11. Darwin & Wallace disagreed on many issues regarding the details of HOW natural selection would work, but both were convinced that it was the primary mechanism by which evolution occurred Darwin: 1809-1882 Wallace: 1823-1913

12. Basic outline of Darwin’s theory: Individuals within a species differ in morphology, physiology, & behavior

13. 2. Some of this variation is heritable

14. 3. Organisms have a huge capacity for increase in numbers, but populations tend to remain +/- constant

15. 4. As a result of competition, some variants will leave more offspring than others

16. 5. If reproductive success is due to the varying trait, and that trait is heritable, it will be passed on to the offspring and become more common in the next generation (Thus evolutionary change by natural selection)

17. ‘Origin’ controversial • among public • human descent from • apes stressed Among many scientists, concept of evolution was largely accepted Much supporting evidence collected from paleontology, morphology, etc. to establish the fact of evolution

18. Mechanism of natural selection was not viewed as favorably - many doubted its power to produce evolution Later, more serious objections e.g. about nature of heredity... do traits blend together in offspring?

19. Is it a problem for Darwin’s theory if inheritance works by blending (e.g. tall parent & short parent produce kids of medium height)? a) yes, it will remove the potential for variation b) no, it does not affect the potential for natural selection as best adapted individuals still leave the most offspring

20. ...and doubts about the age of the earth - Lord Kelvin estimated about 100 million years, based on cooling of earth What did Kelvin leave out of his calculations? Ooops. Didn’t know radioactivity continues to heat earth

21. Darwin’s arguments for evolution & natural selection Variation in domesticated forms: - great variation in animal breeds & cultivated plants - deliberate selection to modify varieties

22. Variation in species in nature: • pointed to variation in individual traits (even in • ‘important’ organs) • - difficulty classifying: varieties vs. species Eastern Screech-Owls barnacles (Semibalanus)

23. Increase in numbers and competition: • - calculated expected # of offspring if all survive • gave examples of increase for plants & animals • introduced to new areas Ox-eye Daisies

24. Geological succession: - new species occur at intervals - ‘modern’ species may be found among extinct forms - intermediate forms between orders found - older forms differ more from modern species • fossils belong to same groups as modern species • in same area trilobite

25. Geographical distribution: • species isolated by strong barriers tend to be distinct, • though physical conditions are similar Lazuli Bunting Indigo Bunting

26. species in the same area are related, even if occupying • different habitats Eastern Gray Kangaroo Lumholtz’s Tree Kangaroo