Ch 25: History of Life

5/10/15

“There is nothing permanent but change.” (Heraclitus) “Chaos always defeats order because it is better organized.” (Terry Pratchett)

Louis Pasteur: Disproving spontaneous generation

Universe forms ~13.8 bya Early solar system formation ~ 4.5 bya

1 5/10/15

Earth’s 1st 1 billion years

Moon formed by a collision

Radiometric Dating

Half-lives 14C: 5,730y 40K: 1.25 by 238U: 4.5 by

Index fossils

2 5/10/15

Arrhenius & Mojzsis Some of the oldest fossils ~3.4 bya (Strelley Pool, Australia) organic trace fossils http://physicsforme.files.wordpress.com/ ~3.8 bya 2011/08/astrobiology3.jpg

Abiogenesis: First step- compounds of life from non-living 1920s

AJ Oparin

JBS Haldane

Miller-Urey experiment (1952/publ 1953)

Stanley Miller Harold Urey 10–15% of the carbon now in the form of organic compounds 2% of the carbon had formed amino acids, with glycine the most abundant (all 20 common ones were found) (In 2008, his student J. Bada reexamined some of Fig 4.2 the vials.)

3 5/10/15

proteinoid Protobionts microspheres

vesicles

4 5/10/15

Sidney Altman

Thomas Cech Other possibilities for early genetic material: PNAs (Miller)

Which came first?

Where do the materials come from? Earth “panspermia”

molecules on space rocks

Note: moves some of the origin question off earth but still have the question…

5 5/10/15

Where did life begin? One hypothesis - deep, hot water

Early microfossils: stromatolites

Shark Bay, Australia (present day)

early O2 production Banded Iron Formations

6 5/10/15

O2 production -> ! Sun Ozone (O3) shield protects us from UV ! Ultravioletrays

3(O2)! ! Upperatmosphere

2(O3)! ! Loweratmosphere SBMFig. 20.06!

Eukaryotes formation of organelles -> multicellularity

endosymbiosis

Grypania spiralis (filaments)

Lokiarchaeota discovery 2015 http://phenomena.nationalgeographic.com/2015/05/06/new-loki-microbe-is-closest-relative-to- all-complex-life/

7 5/10/15

How are organisms related?

old26.21

Current trees of life (largely based on rRNA)

26.21

Horizontal gene But may not be a transfer (26.23) straightforward tree

Ring of life? (old26.23)

Snowball Earth

8 5/10/15

Tour: Proterozoic Era: 2.5 bya -> 542 mya Ediacaran fauna

Paleozoic Era Cambrian Period 542 -> 488.3 mya all current major animal phyla have appeared

Cambrian Period 542 -> 488.3 mya fossil animal embryos Burgess shale

9 5/10/15

Ordovician Period 488.3 -> 443.7 mya first plants?

Silurian Period 443.7 -> 416 mya

Devonian Period 416 -> 359.2 mya “Age of Fishes”

10 5/10/15

Carboniferous Period 359.2 -> 299 mya (large amounts of forest -> major coal deposits)

Permian Period 299 -> 251 mya

Mesozoic Era “Age of Reptiles” Triassic Period 251 -> 199.6 mya Jurassic Period 199.6-> 145.5 mya Cretaceous Period 145.5 -> 65.5 mya

Fig. 20.13!

11 5/10/15

Cenozoic Era (Age of Mammals, Insects, Birds, Flowering Plants) Paleogene Period Paleocene Epoch 65.5 -> 55.8 mya Eocene Epoch 55.8 -> 33.9 mya Oligocene Epoch 33.9 -> 23 mya

Cenozoic Era Neogene Period Miocene Epoch 23 -> 5 mya Pliocene Epoch 5 mya -> 1.8 mya Pleistocene Epoch 1.8 mya -> 10,000 ya Holocene Epoch 10,000 ya -> present? Anthropocene?

Land changes: continental plates and plate tectonics

12 5/10/15

“Recent” continental drift

Mass extinctions: 5 – 8 events (note: appear different at different taxonomic levels)

Q: Is one happening now?

Opportunities & changes

13 5/10/15

Development changes can change bodies Timing changes allometric growth

Development changes can change bodies Timing changes paedomorphosis

axolotl

Development changes can change bodies Changes in genes

Number of Hox genes

How Hox genes are used

14 5/10/15

Evolution does not work toward a snail “goal” limpets eg: mollusk eyes – all useful Nautilus

snail

squids & octopi

Tree of Life video clip with D. Attenborough

http://www.wellcometreeoflife.org/video/

Interactive http://www.wellcometreeoflife.org/interactive/