Thermal History of the Earth and Biosphere

Indiana University

PALEOTEMPARATURES

PALEOTEMPARATURES

Sigman, D.M.; E.A. Boyle (October 2000). "Glacial/interglacial variations in atmospheric carbon

dioxide" Nature 407 (6806): 859–869.

CRUST HARDENS; GLOBAL OCEAN FORMS

Planet has cooled enough that surface temperature allows condensation

Atmosphere is full of an ocean of water vapor

100,000 yrs of rain…. No land above water;

crust is below water, in what are now ocean basins

Hot/warm water, high energy, soup of chemicals

EVIDENCE OF LIFE: WHAT TO LOOK FOR?

Chemical footprints Isotopes of carbon What kind of material

can survive extreme heat? Zircons, “shields,” greenstones…

West Antarctica, Greenland, W. Australia

Organic rich meteorites – organic molecules for first life from space?

The Miller-Urey

experiment

ORIGINS OF MICROORGANISMS Bacteria-like organisms have existed on earth

for about 3.5 billion years Prokaryotes (pre-nucleus): Simple cells Eukaryotes (true nucleus): Complex cells

7

1.  The earth was formed ~4.5 billion years ago

 2.  It took ~500 million years for the crust

to solidify. 

3.  The oldest fossils of microorganisms• 3.5 billion years old,

• embedded in rocks in western Australia                       

3a.  Prokaryotes dominated from 3.5 to 2 billion years ago.

     - During this time, the first divergence occurred:

Bacteria and Archae                                   

Early and modern prokaryotes

DIAMONDS ARE MADE FROM DEAD BACTERIA??? Carbon, the main component of most diamonds, usually

contains an isotope of light carbon (12C), which is utilized by some living organisms. 

Therefore, eclogitic diamonds with large amounts of the isotope 12C, are believed to have an organic origin. 

These were formed from carbon near hydrothermal vents which was also utilized by the bacterial communities near the vents. 

Thus through time, heat and pressure were able to turn the carbon along with the bacterial colonies into diamonds.

"So, those sparklers of yours may just be clumps

of billion-year-old bacterial corpses"

FACTS ABOUT MICROBES

Microbes outnumber all other species and make up most

living matter (~60% of the earths biomass).

Less than 0.5% of the estimated 2 to 3 billion microbial

species have been identified.

Microbial cycling of critical chemical elements such as

carbon and nitrogen helps keep the world inhabitable for

all life forms.

Underground: Chemolithotrophs found in Basalt deposits 1500m (4700 ft) underground in solid rock.

The Sky: Some bacteria spend their whole lives in the atmosphere, growing and reproducing in the clouds above our heads.

On Ice: Some bacterial species live in the ice of glaciers and others have often found in the snows of the North and South poles at -17 and -85°C.

PERMIAN SALT LAYERS (SALT MINE IN BERCHTESGADEN, GERMANY), CA. 250 MILLION YEARS OLD

HALOCOCCUS SALIFODINAE DSM 8989T (FOUND IN ALPINE AND ZECHSTEIN DEPOSITS)

Halococcus dombrowskiiDSM 14522T

Haloarchaeal isolates from Permo-Triassic salt

Extraterrestrial halite

SNC-Meteorites (from Mars; Shergotty, Nakhla Chassigny)Murchison meteorite (from asteroid belt)Monahans meteorite (from asteroid belt)salt pools on the surface of Marsocean on the Jovian moon Europa

Enceladus (moon of Saturn) geysirs

.

Red and blue sodium chloride crystalsin the Monahans meteorite. Each

picture is 1 mm in width.

Antarctica, 1984

Not So Cool: Some bacteria have learned to live in hot springs.

Some species are happy at 75°C while others think even this is

cool. Species of Aquifex can live in water as hot as 95°C. Archaea

are happy to grow deep sea hydrothermal vents at 106°C

The Deep Sea: Bacteria ‘known as Extreme Barophiles’ live at

depths of >10000 m and are able to survive pressures in excess of

1000 times the air pressure at sea level; and they cannot function

properly at pressures less than 400 atmospheres and may die in a

couple of hours if brought to the surface.

Contd…

This 4.5 billion-year-old rock, labeled meteorite ALH84001, is believed to have once been a part of Mars and to contain fossil evidence that primitive life may have existed on Mars

more than 3.6 billion years ago. The rock is a portion of a meteorite that was dislodged from Mars by a huge impact about 16 million years ago and that fell to Earth in Antarctica 13,000 years ago. The meteorite was found in Allan Hills ice field, Antarctica, by an annual expedition of the National Science Foundation's Antarctic Meteorite Program in 1984. It is

preserved at the Johnson Space Center's Meteorite Processing Laboratory in Houston.

THERE'S A "SLEEPING BEAUTY" STORY FOR BACTERIA?

In May 1995, scientists were the prince as they revived 25-40 million year-old bacteria from the stomach of a bee that was preserved in tree sap. 

It was this event that led to the notion of Spielberg's Jurassic Park, where dinosaurs were created after their DNA was extracted from mosquitoes trapped in tree

sap the same way. 

“The dinosaurs, however, were the ones who took the limelight away from the bacteria on

the movie screens”

SERGEI WINOGRADSKY (1856-1953): THE CONCEPT OF CHEMOLITHOTROPHY

Interested in bacteria involved in the cycling of nitrogen and sulfur

Introduced the concept that bacteria could be important biogeochemical agents

SERGEI CONT.

From studies on sulfur-oxidizing bacteria: Chemolithotrophy: the

oxidation of inorganic compounds linked to energy conservation

From studies on nitrogen fixing bacteria, concluded that they obtained their carbon from CO2

From studies, proposed these organisms were autotrophs, specifically chemoautotrophs

Also isolated the first nitrogen-fixing bacteria

Microbial world

Organisms (living)

Infectious agents (non-living)

Prokaryotes (unicellular)

eukaryotes viruses viroids prions

Eubacteria Archaea Algae (unicellular or multicellular)

Fungi (unicellular or multicellular)

Protozoa (unicellular)

Other (multicellular organisms)

ARCHAEA Domain Archaea with 3 kingdoms: 2.7 Ga molecular data (Australia) 3.8 Ga organic matter = chemical fossils?

MethanogensThermophilesHalophiles

DIVERSITY OF SKELETAL COMPOSITIONS *Aragonite *Calcite *Mg-calcite *Opalline silica *Apatite *Organic

Chitin Cellulose Others

*Arenaceous/agglutinated Rare minerals

Celestite (Sr sulfate) Magnetite Rhodocrosite (sp?)

Microbe Approximate range of sizes

Cell type

Viruses 0.01-0.25µm Acellular

Bacteria 0.1-10µm Prokaryote

Fungi 2µm->1m Eukaryote

Protozoa 2-1000µm Eukaryote

Algae 1µm-several meters Eukaryote

The size and cell type of microbes

STROMATOLITE-BUILDING COMMUNITIES

rock-like buildups of microbial mats that form in limestone

include oldest known fossils, 3.5 bya

encode role ancient microorganisms played in evolution of life and shaping earth's environments.

Extensive fossil record of stromatolites; spans 4 by of geological history; occupied every conceivable environment that ever existed.

Today, nearly extinct in marine environments, living a precarious existence in only a few places worldwide.

Modern stromatolites discovered in Shark Bay, Australia in 1956

STROMATOLITES – OXYGEN EXCRETING “COLONIES” POPULATED EARTH

4.  Oxygen began accumulating in the atmosphere about 2.7 billion years ago.

                        a.  Cyanobacteria are photosynthetic

prokaryotes that are still present today à produced oxygen.

 

Banded iron formations are evidence of the age of oxygenic photosynthesis –

approximately 2 BYA in photo

• By comparing ancient stromatolites with modern stromatolites, it has been concluded that filamentous phototrophic bacteria, perhaps relatives of the green nonsulfur bacterium Chloroflexus, formed ancient stromatolites.

• Early Earth was anoxic and much hotter than the present Earth. The first biochemical compounds were

made by abiotic syntheses that set the stage for the origin of life.

PRIMITIVE LIFE: THE RNA WORLD AND MOLECULAR CODING

• The first life forms may have been self-replicating RNAs (RNA life). These were both catalytic and informational. Eventually, DNA became the genetic repository of cells, and the three-part system—DNA, RNA, and protein—became universal among cells (Figure 11.5).

Possible mechanileifsm of evolution of life

Energy generating scheme for primitive cell

• Oxygenic photosynthesis led to development of banded iron formations, an oxic environment, and great bursts of biological evolution (Figure 11.8).

Landmarks of biological evolution

5.  The oldest eukaryotic fossils are ~2 billion years old.

                        a.  Symbiotic community of prokaryotes

living within larger prokaryotes.         Mitochondria and chloroplasts

 6.  The oldest fossils of multicellular organisms are ~1.2 billion years old.

ENDOSYMBIOSIS THEORY (LYNN MARGULIS, 1970’S)

EUKARYOTIC ORIGINS

A. Invagination of plasma membrane B. Endosymbiosis

Symbiosis : An ecological relationship between organisms of 2 different species that live together in direct contact.

How did this get started? prey or parasite

• Mitochondria arose from the Proteobacteria, a

major group of Bacteria.

• Origin of the modern life

7.  The oldest animal fossils are ~700 million years old.

a.  Animal diversity exploded ~540 million years ago.

 

Fossilized animal embryos from Chinese sediments 570 million

years ago.

           8.  Plants, fungi, and animals began

colonizing land ~500 million years ago.                       

a.  First plants transformed the landscape…                       

b.  Then animals were able to take advantage of new niches                                   

Mammals evolved 50 to 60 million years ago.

Self replicating entities

on earth

METHODS FOR DETERMINING EVOLUTIONARY RELATIONSHIPS,  

EVOLUTIONARY CHRONOMETERS,

• The phylogeny of microorganisms is their evolutionary relationships.• Certain genes and proteins are evolutionary

chronometers—measures of evolutionary change. Comparisons of sequences of

ribosomal RNA can be used to determine the evolutionary relationships among organisms.

• SSU (small subunit) RNA sequencing is synonymous with 16S or 18S sequencing.• Differences in nucleotide or amino acid sequence of

functionally similar (homologous) macromolecules are a function of their evolutionary distance.

• Phylogenetic trees based on ribosomal RNA have now been prepared for all the major prokaryotic and

eukaryotic groups.• A huge database of rRNA sequences exists. For example, the Ribosomal Database Project (RDP) contains a large collection of such sequences, now

numbering over 100,000.

Ribosomal RNA

Universal phylogenetic tree

• Life on Earth evolved along three major lines, called domains, all derived from a common ancestor. •Each domain contains several phyla. •Two of the domains, Bacteria and Archaea, remained prokaryotic, whereas the third, Eukarya, evolved into the modern eukaryotic cell.

CHARACTERISTICS OF THE DOMAINS OF LIFE

• Although the three domains of living organisms were originally defined by ribosomal RNA sequencing, subsequent studies have shown that they differ in many other ways.

• In particular, the Bacteria and Archaea differ extensively in cell wall and lipid chemistry (Figure 11.18) and in features of transcription and protein

synthesis (Table 11.2).

• It has been proposed that a prokaryote whose 16S ribosomal RNA sequence differs by more than 3% from that of all other organisms (that is, the sequence is less than 97% identical to any other sequence in the databases), should be considered a new species (Figure 11.25).

Relationship between 16S ribosomal RNA sequence similarity and genomic DNA:DNA hybridization