The exam is closed book. It consists of 5 short essay questions (10 points each) and 3 long essay questions (25 points each); total maximum points 125. The 5 short essay questions should be less than ~ 1 page in the blue book. The 3 long essay questions should be 2-3 pages in the blue book; the last one should also be marked on the attached figure. Please put your name on everything you hand in.

Question 1. Taphonomy is the study of how living organisms become fossilized. What ‘factors of destruction’ prevent of affect the preservation of an organism as a fossil? Under what circumstances are these ‘factors of destruction’ not (very) effective and do we see excellent preservation, even of soft parts?

Mechanical (e.g., abrasion, breakage), biological (e.g., predation), and chemical (diagenesis; oxidation). Not very effective under low oxygen conditions (especially when rapidly buried), very low temperatures (freezing in ice). Lecture 1, chapter 1 textbook

Question 2. In what major way did the Vendobiont ecosystem differ from more recent ecosystems? Would you think that the Vendobiont ecosystem had a higher or lower diversity than later ecosystems? Why?

Vendobiont ecosystem had no/very few predators (no organisms with mouths); therefore there was no ‘cropping’; therefore we would expect lower diversity (‘cropping principle: higher diversity when organisms are eaten, preyed upon).

Lecture 10

Question 3. What is the major driver of evolution according to the ‘Red Queen hypothesis’? Would evolution occur in a hypothetical world where there is no physical or chemical environmental change (stable world) according to this hypothesis? If one transported a pack of lions back into Eocene times using a time machine, would these lions do very well or very poorly in catching Eocene herbivores, according to the Red Queen hypothesis? Why?

Competition between organisms. Yes, because if evolution is largely driven by inter-organism competition (‘arms race’), it will also occur in the absence of environmental change. Recent lions would do very well in the Eocene, because they have become much more efficient predators in the time between the Eocene and now.

lectures 6, 11

Question 4. Describe the life of a reef coral: how does it obtain its energy? Does it live in a high or low nutrient environment? Over geological time, has the same group of organisms that dominate in reefs today (Scleractinian corals) always been the dominant reef builder?

Reef corals obtain most (~95%) of their energy from internal algal symbionts (zooxanthellae; dinoflagellates), and only little by eating (tentacles grab food; cilia trap particles). Because they obtain energy from internal symbionts energy is contunally recycled within the coral animals, which thus can live well in low nutrient environments; in high nutrient environments they do not do well because abundant algal growth takes light away from their symbionts. No, over the Phanerozoic many different groups have been reef builders (e.g., rugose corals and tabulate corals in the Paleozoic).

Lecture 4

Question 5. In about half a square km in a coral reef, animals have been observed to belong to 10 Phyla, with about 200 species. In about half a square km in a tropical rain forest, animals belong 3 Phyla, with about 950 species. How do these regions compare in diversity and disparity? Why do you say so? Name 3 Phyla that are present in the coral reef. Which is the dominant Phylum (most species) of these 3? Name 2 Phyla present in the rainforest; which is the dominant (most species) Phylum there? When did these Phyla originate?

Coral reef has higher disparity: more Phyla present means more organisms with fundamentally different ‘building plans’; forest has higher diversity (more species). Coral reefs animal Phyla: Cnidaria (corals themselves, jellyfish); Chordates (fish); Arthropods (shrimp, lobster); Mollusca (bivalves, octopus, snails), Bryozoa. Dominant; probably Cnidaria, but rthropoda would also be a good guess. Forest animal Phyla: Chordates (mammals, birds, snakes, frogs, lizards); Arthropods (insects, centipedes); Mollusca (snails); dominant Arthropods. All Phyla mentioned originated somewhere in the late Precambrian; fossil records since Cambrian explosion; only Cnidaria have a fossil record going back through late Precambrian (Vendobionta).

various lectures, including lecture 11

Question 1.

What was the Cambrian Explosion? About how long ago did it happen? Describe how climate at that time has been hypothesized to have influenced evolution of the major Phyla, as well as how biotic factors have been said to have affected evolution at that time.

A geologically short period (maximum 25 million years) during which bilaterally symmetrical animal Phyla with skeletons first show up in the fossil record, and rapidly diversify. 543 Ma. Climate factors: in the late Proterozoic the global climate has been said to be extremely unstable, alternating between ‘snowball earth’ episodes and extreme greenhouse intervals, with ice at sea level in the tropics. Biotic factors: extreme competition in a snowball world where eukayote life could survive only in small areas (e.g., tropical open ocean); evolution of genes (especially hox genes); evolution of predation (cropping principle).

lecture 10

Question 2.

Describe the mass extinction at the end of the Cretaceous: probable cause? Global environmental effects? What evidence do we have for the probable cause? Which common organisms became extinct on land and in the sea? Name some organisms which survived the mass extinction.

Probably cause: impact of asteroid on Yucatan peninsula; possibly exacerbated by outflow of major flood basalts (Deccan traps, India). Global effects impact: dark because of dust, thus extinction photosynthesizers at base of food chain; possibly cold (short term); possibly warm in the long term because of greenhouse gases from impact on limestones; possibly strong acid rain. Evidence: buried crater; pieces of asteroid; Iridium enrichment; shocked quartz grains; tektites. Extinct on land: dinosaurs; in oceans: ammonites, mosasaurs; many reefs organisms; oceanic phytoplankton. Survivors: land plants; crocodiles, turtles, mammals, arthropods.

Lecture 8; K/T web write up

Question 3.

Life on Earth (as shown on the attached figure) developed from a shared ancestor. Which characters are shared by all life on Earth, thus were probably inherited from that ancestor? What are the three domains of life? Describe the main characters of each domain concisely (unicellular /multicellular? autotroph/heterotroph? Complexity of cells?). Which groups do we recognize within the morphologically most complex of the three domains?

All life on earth:

• Cells surrounded by membrane
• DNA
• DNA->RNA->proteins made in ribosomes (central dogma of biology)

Three domains:

1. Archaea (prokaryotes, unicellular, cells without nucleus and organelles; heterotrophs or autotrophs)
2. Bacteria (prokaryotes, unicellular, cells without nucleus and organelles; heterotrophs or autotrophs);
3. Eukarya (unicellular or multicellular; large and complex cells with nucleus and organelles).
   • Protista: unicellular, hetrotroph or autotrophs
   • Fungi are multicellular, heterotroph
   • Plants are multicellular, autotroph
   • Animals are multicellular, heterotroph.

lecture 3; write up Phyla

The figure shows ‘The Evolution of Animals’ (one of these groups), as reconstructed by scientists who use a different way of classification than we have been using in class, calling its approach ‘Evolution and Engineering Evolution’. The oval object in the middle, at about 2/3 height of the poster (called ‘The Gallertoid’) represents the (hypothetical) ancestral multi-cellular animal. Diverging lines show the various Phyla, with animals shown in yellowish towards the outer edge of the group, cross-sections in the blue-ish color (with body cavities in black). The broad groupings are similar to these we have considered in class. Mark the following taxonomic groups on this poster, by circling the organisms that belong in that group and writing their numbers in the list below next to the lines encircling each group:

1. Phylum Porifera

2. Phylum Cnidaria

3. Group Deuterostomates:

• 4. Phylum Chordates
• 5. Phylum Echinodermata

6. Group Protostomates

• 7. Group Ecdysozoa: molters (including Phylum Arthropoda)
• 8. Group Lophotrochozoa
  • Superphylum Lophophorates (including Phyla Brachiopoda, Bryozoa)
  • Superphylum Trochozoa (including Phylum Mollusca)