Presentation on theme: "Three Parts 1.The Tree of Life and LUCA (cenancestor) 2.Map tree onto the fossil record – key events and their biogeochemical impact 3.Evidence for a."— Presentation transcript:
Three Parts 1.The Tree of Life and LUCA (cenancestor) 2.Map tree onto the fossil record – key events and their biogeochemical impact 3.Evidence for a three phase history of life
Why? The lab. now has several projects which study evolution using protein structure Chris’s and Song’s paper which has now been accepted by PNAS provides a direct link between evolution and geochemistry in a way that has not been done before At every step we should look for connections between events we see through structure and changes in the earth’s environment that might have triggered such changes or vice-versa
Whether the deep ocean became oxic or euxinic following the rise in atmospheric oxygen (~2.3 Gya) is debated, therefore both are shown (oxic ocean-solid lines, euxinic ocean-dashed lines). The phylogenetic tree symbols at the top of the figure show the theoretical periods of diversification for each Superkingdom. Theoretical levels of trace metals and oxygen in the deep ocean through Earth’s history Replotted from Saito et al, 2003 Inorganica Chimica Acta 356: 308-318
Metal Binding Proteins are Not Consistent Across Superkingdoms Since these data are derived from current species they are independent of evolutionary events such as duplication, gene loss, horizontal transfer and endosymbiosis
e - transfer proteins Same Broad Function, Same Metal, Different Chemistry Induced by the Environment? Fe-S clusters Fe bound by S Cluster held in place by Cys Generally negative reduction potentials Very susceptible to oxidation Cytochromes Fe bound by heme (and amino-acids) Generally positive reduction potentials Less susceptible to oxidation
This is not so much the dissection of a paper, but the use of a review across a broad area to get us thinking in different ways
The Gaia Hypothesis Gaia - a complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback system which seeks an optimal physical and chemical environment for life on this planet.biosphereatmosphereoceanssoil James Lovelock Gaia (pronounced /'ge ɪ.ə/ or /'ga ɪ.ə/) "land" or "earth", from the Greek Γα ῖ α; is a Greek goddess personifying the EarthGreekEarth
The Buddha once told a story about a king who ordered a group of blind men to be presented with an elephant. Each man only touched a different part of the animal. The king then asked them what an elephant is like. "Those blind people who had been shown the head of the elephant replied, 'An elephant, your majesty, is just like a water jar.' Those blind people who had been shown the ear of the elephant replied. "An elephant, your majesty, is just like a winnowing basket.' Those blind people who had been shown the tusk of the elephant replied, 'An elephant, your majesty, is just like a plowshare.' Those blind people who had been shown the trunk replied, 'An elephant, your majesty, is just like a plow pole.' Those blind people who had been shown the body replied, 'An elephant, your majesty, is just like a storeroom.' Those blind people who had been shown the foot replied, 'An elephant, your majesty, is just like a post.' Those blind people who had been shown the hindquarters replied, 'An elephant, your majesty, is just like a mortar.' Those blind people who had been shown the tail replied, 'An elephant, your majesty, is just like a pestle.' Those blind people who had been shown the tuft at the end of the tail replied, 'An elephant, your majesty, is just like a broom.' "Saying 'An elephant is like this, an elephant is not like that! An elephant is not like this, an elephant is like that!' they fought each other with their fists." (1997) The Udana: Inspired Utterances of the Buddha. Ireland JD, translator. Kandy: Buddhist Publication Society. Inspired by Carl Zimmer
Interdisciplinary – Palaeontology and Neontology They are complementary Readings from Carl Zimmer’s perspective Neontology From Wikipedia, the free encyclopedia Neontology is the part of biology which – in contrast to paleontology – deals with now living (recent) organismsbiologypaleontologyorganisms
Evolution of Cell Structure – A Three Phase History of Life Negibacteria to Unimembrana via loss of outer membrane – important for endosymbiosis Glycobacterial revolution – anoxic to oxic Neomura – eukaryotic cell development
Three eras of unequal length punctuated by two short periods of dramatic change – the glycobacterial and neomuran which had dramatic effect on the earth Most phyla probably originated in bursts of adaptive radiation and quantum evolution soon after these major innovations Integrated View of Paleontology, Cell Physiology and to Some Extent Molecular Biology
Ecosystems and biogeochemical cycles were simple Life depended on the single photosystem of chlorobacteria ie anoxygenic photosynthesis using H 2 or H 2 S as a hydrogen donor Ecosystems were anaerobic Nitrogen fixation very old to stabilize biomass (vertical little LGT) Photosystem duplication – later fixed in cyanobacteria Rising oxygen – reduction in greenhouse gases – first glaciation Age of Eobacteria
This is Just One Viewpoint – Ecological Niches Plays a Role An alternative theory proposes that the deep ocean became euxinic (anoxic and sulfidic) around 1.8 Gyr ago (6, 7), prior to an oxygenation of deep waters around 1 Gyr (8). 6.Canfield, D. E. & Teske, A. (1996) Nature 382, 127-132. 7.Arnold, G. L., Anbar, A. D., Barling, J. & Lyons, T. W. (2004) Science 304, 87-90. 8.Canfield, D. E. (1998) Nature 396, 450-453.
Long age of the cyanobacteria – oxygenic photosynthesis Biosphere separated into aerobic and anaerobic regions Eobacteria expanded into all regions Proteobacteria to every biogeochemical zone not aerobic nor methane rich Diverification of 6 glycobacterial phyla Oxygenation led to reduction in greenhouse gases – snowball earth? Age of Cyanobacteria
Neomuran revolution – origin of epithelial and mesenchymal (embryonic) connective tissue Rigid murein replaced by glycoproteins – evolution of phagotrophy (engulf feeding), digestive enzymes – complete eukaryote – endoskeleton, nucleus, mitosis, cilium Earlier occurrence on other planets – more intelligent life out there Cambrian explosion of animals via flagellates and sponges Invention of archaebacterial methangenesis, methanotrophs, origin of the chloroplast (protozoan capture from cyanobacteria), secondary symbiogenesis, fungal hyphal heterotrophy Emergence of methanogenesis – CO 2 levels drop – cooling – snowball earth Followed by increase in methanotropes reduced methane emission temperatures rise – snowball earth ends The Age of Eukaryotes
Things for Us to Think About Proximity - multi-gene lateral transfer would most likely require close genome proximity Emergence of Photosystems I and II a major event – what does our superfamily and family data tell us?
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