1. Genetics Evolut ion Speciation Diversity of Life http://hismasterstoys.blogspot.com/2007/04/evolution-poster.html

2. Macro-evolution -- study of the history of life Intro to phylogenies & the fossil record as tools The Cambrian Explosion (543 mya) -- rapid diversification of metazoan animal life Genetic mechanisms of major morphological change Adaptive radiations -- key innovations lead to rapid diversification Mass extinctions -- environmental catastrophes lead to loss of diversity

4. Which one of these trees is different?

5. Shared, derived traits are used to build phylogenies.

6. The unusual shape of an ankle bone is a shared derived trait for the “artiodactyls”, hoofed animals with an even number of toes. Whales have traditionally been thought to descend from a group of carnivorous animals outside of the artiodactyls.

7. Recent molecular work suggests, in contrast, that whales arose from within the artiodactyls.

8. SINE = short interspersed nuclear elements. Class of transposable elements, or “selfish DNA”. Contain genes to get themselves copied and inserted. Provide record of evolutionary history. Draw artiodactyl phylogeny showing gain of SINEs.

9. The Fossil Record

10. 1. Death and quick burial 2. Various fossilization methods - - for example, cavity filled with minerals. 3. Fossil must must later be exposed, at least partially, so that people can find it. Rocks must not be deformed by metamorphosis, or fossils would be destroyed. Formation and Recovery of Fossils

11. FYI -- types of fossils. Don’t memorize.

12. http://news.bbc.co.uk/2/hi/science/nature/7324564.stm New method -- can visualize using high energy light, “X-ray” through solid amber.

13. The fossil record is very incomplete Archaeopteryx -- oldest bird in fossil record.

14. The fossil record contains biases. 1. Habitat bias -- organisms must be buried in sediment. Most common on mud flats, swamps, beaches…. 2. Taxonomic bias -- hard parts preserve best Shells, teeth, bones, etc. Soft worms not so much. 3. Temporal bias -- very old fossils likely to be lost through metamorphism or erosion. 4. Abundance (maybe this isn’t a bias….) -- common species more likely to be preserved.

15. Life’s Timeline Dates to know: 4.6 bya -- earth formed 3.6 bya -- life began ~ 2 bya -- Eukaryotes* arose 1 bya -- first multicellular organism 543 mya end of PreCambrian, beginning of Paleozoic 250 mya beginning of Mesozoic 65 mya beginning of Cenozoic *Eukaryotes have a nuclear membrane and organelles such as mitochondria and chloroplasts Prokaryotes (Archaea and Bacteria) do not

20. Each point represents a comparison between two species. Points near the origin are comparing closely-related species. By fossil record-- time to common ancestor Creation of a molecular clock

21. Used mtDNA clock calibrated w/apes to show that all living humans have a common ancestor ~ 150,000 years ago (not 2 mya).

22. The Cambrian explosion was the rapid morphological and ecological diversification of animals that occurred during the Cambrian period. These groups don’t fossilize well; that’s why we don’t see them until recently http://www.ucmp.berkeley.edu/phyla/metazoafr.html

23. Cambrian Era begins here.

24. The Doushantuo Microfossils Found in China, discovered 1998 in fertilizer mine Tiny sponges Animal embryosshallow water marine Algaehabitat Pictures on next slide.

25. Fertilized egg 2 cell embryo 4 cell embryo 16 cell embryo

26. The Ediacaran Faunas In Australia Sponges Jellyfish Segmented animals, but with no heads Pictures on next slide

28. The Burgess Shale Faunas In Cambrian period-- midst of 40 million year “explosion” New species of pre-existing groups like sponges, jellyfish Many new groups! Arthropods (today includes insects, crustaceans) Mollusks (today includes clams, octopus) Starfish Worms Chordates (group that now includes us) A cuttlefish is a cephalopod, which is a mollusk. An arthropod. A polychaete worm.

29. New features include: Exoskeletons Heads, tails Appendages Eyes Mouths Sophisticated movements: swim, burrow, run Why all this so quickly?

30. The Genetic Mechanisms of Change The new field of “evo-devo” is providing insights into how major events in the history of life occurred, by revealing the genetic mechanisms involved. (Paleontologists are also collaborating, to try to understand the environmental triggers.)

31. Gene Duplications and the Cambrian Explosion

32. Hox Gene Expression in Drosophila Hox genes are transcription factors; bind to DNA to turn on genes. Each copy of the hox gene is expressed in a different location of the embryo.

33. Gene duplications

34. CHECK YOUR UNDERSTANDING You should be able to describe how data from molecular genetics, phylogenies, and the fossil record are being combined to provide insight about the radiation of animals. Images from http://www.dnr.sc.gov/marine/sertc/gallery.htm

35. Adaptive Radiations Adaptive radiations exhibit rapid diversification associated with new ecological opportunities (caused by extinction or colonization) and/or new morphological innovations.

37. Adaptive Radiations: 1. Colonization Events as a Trigger

38. Finchlike ancestor -- eats seeds Desendents eat eat insects, flowers, as well

39. 30 closely related species Tremendous morphological diversity Mosslike, vines, trees

40. Convergent evolution Selection will fill vacant niches.

41. Adaptive Radiations: 2. Role of Morphological Innovation

42. Exoskeleton, wings, 6 legs 10,000,000 species

43. Flowers permit specialized mating 250,000 species

44. 2nd set of jaws in throat permits specialized feeding: Crushing snails, scraping algae, etc. 300 species in Lake Victoria alone.

45. 10,000 species of birds

46. Mass Extinctions Mass extinctions have occurred repeatedly throughout the history of life. They rapidly eliminate the majority of species present. Afterwards, speciation causes re- population of vacant niches.

47. Paleo/Mesozoic Meso/Cenozoic

48. How do background and mass extinctions differ? Mass extinctions caused by sudden, extraordinary changes in the environment. Produce extinctions that are largely random with respect to fitness of individuals (but may influence some taxa selectively).

49. What Killed the Dinosaurs? http://www.vorpalcloud.org/~bp5975/gallery/Dinosaurs-at-UNC-Charlotte/IMG_0003

52. Asteroid approx 10 km across. Incredible impact. Fireball; catastrophic fires worldwide. Sulfuric acid rain. Dust/ash/soot block sun.

53. Mammals experienced adaptive radiation following the last mass extinction. http://www.mun.ca/biology/scarr/Mammalian_Adaptive_Radiation.htm