1. DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE
CHAPTER 22

2. “ Nothing in Biology makes sense except in the light of evolution”
T.B. Dobzhansky

3. Figure 22.2 Fossils of trilobites, animals that lived in the seas hundreds of millions of years ago

4. HISTORICAL CONTEXT
Carl Linnaeus ( ) – founder of taxonomy (scientific name) grouped similar species into same genus
Georges Cuvier ( ) – catastrophism – different species in layered rock due to catastrophic events like floods

5. James Hutton ( ) – gradualism – profound change is a cumulative product of slow but continuous process; ex. Rivers making canyons
Charles Lyell ( ) – uniformitarianism – geological process have not changed throughout Earth’s history
Jean Baptiste Lamarck ( )- thought acquired characteristics can be passes on to offspring

6. Figure 22.3 Formation of sedimentary rock and deposition of fossils from different time periods

7. Figure 22.4 Strata of sedimentary rock at the Grand Canyon

8. Figure 22.18 Charles Darwin in 1859, the year The Origin of Species was published

9. CHARLES DARWIN (1809-1882) Worked on the HMS Beagle in 1830’s
Observed and collected thousands of different species
Galapagos Islands (west of S. America) most interesting

10. Figure 22.5 The Voyage of HMS Beagle

11. Figure 22.6 Galápagos finches

12. “The Galápagos tortoise (or Galápagos giant tortoise), is the largest living tortoise, endemic to nine islands of the Galápagos archipelago. Adults of large subspecies can weigh over 300 kilograms (660lb) and measure 1.2 meters (4 ft) long. Although the maximum life expectancy of a wild tortoise is unknown, the average life expectancy is estimated to be years.”
Source: en.wikipedia.org/wiki/Gal%C3%A1pagos_tortoise

13. Darwin read Lyell’s Principles of Geology and felt age of earth was much older than previously thought
1844 Darwin wrote essay on the origin of species
1858 – Alfred Wallace sends manuscript to Darwin about Natural Selection

14. Lyell presented Wallace’s paper as well as Darwin’s 1844 essay to scientists
1859 The Origin of Species published by Darwin
Descent with modification
Natural selection (the mechanism)

15. Figure 22.7 Descent with modification

16. DARWIN’S OBSERVATIONS
Population size can lead to struggle for existence
Individuals who inherited characteristics best fit for environment are likely to have more offspring than less fit individuals
Leads to gradual change in a population

17. NATURAL SELECTION A population evolves, not an individual!
Acquired characteristics may be adaptable but are not inherited!!
The environment does not create a best fit characteristic, but selects for it!

18. Figure 22.9 A few of the color variations in a population of Asian lady beetles

19. Figure 22.11b Artificial selection: diverse vegetables derived from wild mustard

21. Goldendoodle and a liger
AP:April. 29, 2005
ST. THOMAS, Barbados - It's male.  But what is it?  A zonkey? A deebra?  That's the debate in Barbados since a zebra gave birth to a foal sired by a donkey.

22. EVIDENCE OF EVOLUTION
Biogeography – geographical distribution of species
Ex. Islands with similar species to mainland
Fossil record – transitional forms
Comparative Anatomy – homologous structures among different organisms

23. Vestigial organs –marginal, if any importance, remnants of structures that once served a function
Whale pelvis and leg bones and human appendix
Comparative Embryology – most vertebrates share common early development (gill slits)
Molecular Biology – similar overall DNA, similar proteins (ex. Cytochrome c)

26. Figure 22.12 Evolution of insecticide resistance in insect populations

27. Figure 22.13 Evolution of drug resistance in HIV
All 3 patients treated with anti-HIV drug, 3TC. After a few weeks, 3TC-resistant viruses compromise 100% of the population.

28. Figure 22.14 Homologous structures: anatomical signs of descent with modification

29. Table 22.1 Molecular Data and the Evolutionary Relationships of Vertebrates

30. Figure 22.15 Different geographic regions, different mammalian “brands”

31. Figure 22.16 The evolution of fruit fly (Drosophila) species on the Hawaiian archipelago

32. Figure 22.17 A transitional fossil linking past and present