evolution alan ward. evolution formation of the earth geochemical dating places the earth ’ s age...

19
Evolution Alan Ward

Upload: mitchell-tucker

Post on 04-Jan-2016

221 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Evolution

Alan Ward

Page 2: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Evolution

Page 3: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Formation of the EarthGeochemical dating places the Earth’s age at 4.6 billion years

The oldest rocks:

SW Greenland – Itsaq Gneiss Complex (3.86 billion years old)•Volcanic•Carbonate•Sedimentary

Western Australia – Warrawoona seriers; Towers formation; Pilbara supergroups

South Africa – Swaziland supergroup

Evolution

Page 4: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Hadean

ArcheanOldest rocks from Isua Supercrustal Group

Oldest fossils

Formation of the earth

Stromatolites and cyanobacterria

first eukaryotesProterozoic

Explosion of phytoplanckton

Decline in phytoplanktonCambrian explosionPlants invade the landDinosaurs

Evolution

Page 5: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

EvolutionWays of studying the origin of life

Page 6: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Essential characteristics of Life

Replication

Catalysis

Boundary layer

RNA World Early cellular life Modern cellular life

proteins take over as catalysts

DNA takes over replication

Evolution

Page 7: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Self-replicating, catalytic RNA molecules

Ribozymes

Modern examples

Self-splicing mRNA

RNAse P

Ribosomes

50S ribosome

RNA

protein

RNA World Replication and Catalysis

Page 8: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Lipoprotein vesicles

The cell – a boundary layer

Schrum et al., (2010) The origins of cellular life. Cold Spring Harbour Perspect Biol . Origins of Life Sunject Collection

Page 9: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Energy generationEssential characteristics of Life

Proton Motive Force

or

Substrate level phosphorylation

FeS H2S + CO2 CH3SH FeS/NiS CH3SH + CO CH3COSCH3

CH3COSCH3 + Pi CH3CO-P + CH3SH

Page 10: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Warm little pool

Page 11: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland
Page 12: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland
Page 13: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

RNA WorldThe ribosome is a ribozyme

Page 14: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

DNA evolution

• replication infidelities • effects of external and internal environmental

mutagens (UV, O2, mutagens, …)• DNA rearrangements• acquisition of genetic information

Page 16: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Replication- Bacterial genome

Page 17: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Bacterial genomes are sampling rather than accumulating sequences, counterbalancing gene acquisition with gene loss

Estimated rate of acquisition by lateral gene transfer 31 kb/Myr

Point mutations introduce 22 kb of variant DNA per Myr

Total acquired DNA since divergence of E. coli and S. enterica 100 Myr ago 3Mb

DNA different by LTG between E. coli and S. enterica 803 Kb

Lateral Gene Transfer

Escherichia coli (compared to Salmonella enterica)

Lawrence JG Ochman H (1997) Amelioration of Bacterial Genomes: Rates of Change and Exchange. J Mol Evol (1997) 44:383–397

Page 18: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

Lateral Gene Transfer

Page 19: Evolution Alan Ward. Evolution Formation of the Earth Geochemical dating places the Earth ’ s age at 4.6 billion years The oldest rocks: SW Greenland

MacFadden BJ (2005) Fossil Horses— Evidence for Evolution. Science 307, 1728 – 1730