History and Diversity of Life I. Origin of Life Hypotheses

A. The Early Earth and Earth History 4.5 bya: Earth Forms Graviational sorting of materials…heavy to the core, gases released under pressure…

The Early Earth and Earth History - Earliest Atmosphere - probably of volcanic origin Gases produced were probably similar to those released by modern volcanoes (H2O, CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 and CH4

A. The Early Earth and Earth History 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks

A. The Early Earth and Earth History 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils Stromatolites - communities of layered 'bacteria'

A. The Early Earth and Earth History 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils Putative microfossil bacteria from Australia that date to 3.4 by

A. The Early Earth and Earth History 2.3-2.0 bya: Oxygen in Atmosphere 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

A. The Early Earth and Earth History 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

A. The Early Earth and Earth History 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

A. The Early Earth and Earth History 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 0.5 bya: Cambrian 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

A. The Early Earth and Earth History 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 0.5 bya: Cambrian 0.24 bya:Mesozoic 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

A. The Early Earth and Earth History 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 0.5 bya: Cambrian 0.24 bya:Mesozoic 0.065 bya:Cenozoic 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

A. The Early Earth and Earth History 4.5 million to present (1/1000th of earth history) 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 0.5 bya: Cambrian 0.24 bya:Mesozoic 0.065 bya:Cenozoic 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

B. The Formation of Biologically Important Molecules - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously Aleksandr Oparin (1894-1980) J.B.S. Haldane (1892-1964)

B. The Formation of Biologically Important Molecules - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously - Miller-Urey (1953) all biologically important monomers have been produced by these experiments, even while changing gas composition and energy sources

C. Acquiring the Characteristics of Life Three Primary Attributes: - Barrier (phospholipid membrane) - Metabolism (reaction pathways) - Genetic System

C. Acquiring the Characteristics of Life 1. Evolution of a Membrane - form spontaneously in aqueous solutions

C. Acquiring the Characteristics of Life Evolution of a Membrane Metabolic Pathways Evolution of a Genetic System - conundrum... which came first, DNA or the proteins they encode? DNA RNA (m, r, t) protein

C. Acquiring the Characteristics of Life Evolution of a Membrane Metabolic Pathways Evolution of a Genetic System - conundrum... which came first, DNA or the proteins they encode? DNA DNA stores info, but proteins are the metabolic catalysts... RNA (m, r, t) protein

C. Acquiring the Characteristics of Life Evolution of a Membrane Metabolic Pathways Evolution of a Genetic System - conundrum... which came first, DNA or the proteins they encode? - Ribozymes info storage AND cataylic ability

C. Acquiring the Characteristics of Life Evolution of a Membrane Metabolic Pathways Evolution of a Genetic System - conundrum... which came first, DNA or the proteins they encode? - Ribozymes - Self replicating molecules - three stage hypothesis

Stage 1: Self-replicating RNA evolves

(REPLICATION ENZYMES) Stage 1: Self-replicating RNA evolves RNA m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 2: RNA molecules interact to produce proteins... if these proteins assist replication (enzymes), then THIS RNA will have a selective (replication/reproductive) advantage... chemical selection.

(REPLICATION ENZYMES) DNA Reverse transcriptases m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 3: Mutations create new proteins that read RNA and make DNA; existing replication enzymes replicate the DNA and transcribe RNA.

Can this happen? Are their organisms that read RNA and make DNA?

Can this happen? Are their organisms that read RNA and make DNA? yes - retroviruses....

(REPLICATION ENZYMES) DNA m- , r- , and t- RNA Already have enzymes that can make RNA... PROTEINS (REPLICATION ENZYMES) Stage 3: Mutations create new proteins that read RNA and make DNA; existing replication enzymes replicate the DNA and transcribe RNA.

(REPLICATION ENZYMES) DNA m- , r- , and t- RNA Already have enzymes that can make RNA... PROTEINS (REPLICATION ENZYMES) Stage 3: Mutations create new proteins that read RNA and make DNA; existing replication enzymes replicate the DNA and transcribe RNA.

(REPLICATION ENZYMES) This is adaptive because the two-step process is more productive, and DNA is more stable (less prone to mutation). DNA m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 4: Mutations create new proteins that replicate the DNA instead of replicating the RNA...

(REPLICATION ENZYMES) This is adaptive because the two-step process is more productive, and DNA is more stable (less prone to mutation). DNA And that's the system we have today.... m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 4: Mutations create new proteins that replicate the DNA instead of replicating the RNA...

D. Summary: STEPS REQUIRED FOR THE SPONTANEOUS, NATURAL FORMATION OF LIFE, and the evidence to date: 1. Spontaneous synthesis of biomolecules - strong evidence; Miller-Urey experiments. 2. Polymerization of monomers into polymers (proteins, RNA, sugars, fats, etc.) - strong evidence;  Fox and Cairns-Smith experiments. 3. Formation of membranes - strong evidence; behavior of phospholipids in solution. 4. Evolution of metabolic systems - reasonable hypotheses, and genetic similarity in genes involved in particular pathways (suggesting gene duplication and subsequent evolution of new genes and elaboration of existing pathways) 5. Evolution of a genetic system - a reasonable hypothesis and significant corroborating evidence that it could happen. But no experimental evidence of the process evolving through all three steps. 6. How did these three elements (membrane, metabolism, genetic system come together?) a few untested hypotheses.

Diversity Origin of Life A Brief History of Life

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 2.0 bya: first eukaryotes 2.3-2.0 bya: Oxygen 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.5 bya: Oldest Fossils Grypania spiralis – possibly a multicellular algae, dating from 2.0 by

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline - Life was exclusively bacterial for ~40% of life’s 3.5 by history - Ecosystems evolved with bacterial producers, consumers, and decomposers. - Multicellular eukaryotic organisms evolved that use and depend on these bacteria

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 0.065 bya: Cenozoic 0.7 bya: first animals 2.0 bya: first eukaryotes 2.3-2.0 bya: Oxygen 0.5 bya: Cambrian 0.24 bya:Mesozoic 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.5 bya: Oldest Fossils For ~40% of life’s history, life was exclusively bacterial

Ecological Roles Played By Prokaryotes ATMOSPHERE N fixation Photosynthesis Respiration BIOSPHERE Energy harvest of animals and plants Absorption Decomposition LITHOSPHERE

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System - a ‘nested’ hierarchy based on morphology

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System Cladistics and Phylogenetic Systematics Evolution explained this nested pattern as a consequence of descent from common ancestors. Modern biologists view the classification system as a means of showing the phylogenetic relationships among groups

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. NEW HOMINIDAE Genera: Australopithecus Homo PONGIDAE Pan Gorilla Pongo OLD

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. OLD Phylum: Chordata Subphylum: Vertebrata Class: Reptilia Class: Mammalia Class: Aves

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System Cladistics and Phylogenetic Systematics NEW

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. OLD

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. NEW

III. The Prokaryote Domains: Eubacteria and Archaea Overview Bacteria Archaea Eukarya No nucleus no nucleus nucleus no organelles no organelles organelles peptidoglycan no 1 RNA Poly several F-methionine methionine Introns rare present common No histones histones Circular X’some Linear X’some

III. The Prokaryote Domains: Eubacteria and Archaea Overview 1. Archaea “Extremeophiles” - extreme thermophiles: sulphur springs and geothermal vents - extreme halophiles: salt flats “Methanogens” Also archaeans that live in benign environments across the planet.

III. The Prokaryote Domains: Eubacteria and Archaea Overview 1. Archaea 2. Bacteria - proteobacteria - Chlamydias - Spirochetes - Cyanobacteria - Gram-positive bacteria

III. The Prokaryote Domains: Eubacteria and Archaea Overview 1. Archaea 2. Bacteria These groups are very diverse genetically and metabolically. Their genetic diversity is represented by the “branch lengths” of the groups, showing how different they are, genetically, from their closest relatives with whom they share a common ancestor.

III. The Prokaryote Domains: Eubacteria and Archaea Overview B. Metabolic Diversity of the Prokaryotes The key thing about bacteria is their metabolic diversity. Although they didn't radiate much morphologically (spheres, rod, spirals), they DID radiate metabolically. As a group, they are the most metabolically diverse group of organisms.

III. The Prokaryote Domains: Eubacteria and Archaea Overview B. Metabolic Diversity of the Prokaryotes 1. Responses to Oxygen: all eukaryotes require oxygen. bacteria show greater variability: - obligate anaerobes - die in presence of O2 - aerotolerant - don't die, but don't use O2 - facultative aerobes - can use O2, but don't need it - obligate aerobes - require O2 to live

III. The Prokaryote Domains: Eubacteria and Archaea Overview B. Metabolic Diversity of the Prokaryotes C. Ecological Importance - major photosynthetic contributors (with protists and plants) - the only organisms that fix nitrogen into biologically useful forms that can be absorbed by plants. - primary decomposers (with fungi) pathogens endosymbionts with animals, protists, and plants

Bacteria still drive major dynamics of the biosphere

The Diversity of Life I. Origin of Life Hypotheses II. Classifying Life III. The Prokaryote Domains: Bacteria and Archaea IV. The Domain Eukarya

I. A Brief History of Life II. Classifying Life The Diversity of Life I. A Brief History of Life II. Classifying Life III. The Prokaryote Domains: Bacteria and Archaea IV. The Domain Eukarya A. Overview: 2.0 billion years of evolution Very diverse Unicellular, colonial, multicellular

- membrane bound nucleus - organelles - sexual reproduction and IV. The Domain Eukarya A. Overview: - membrane bound nucleus - organelles - sexual reproduction and meiosis

IV. The Domain Eukarya Overview: Origin of the Eukarya 1. Origin of Organelles

IV. The Domain Eukarya Overview: Origin of the Eukarya 1. Origin of Organelles

IV. The Domain Eukarya Overview: Origin of the Eukarya C. Diversity of Eukarya

Parabasalida (Trichomonas) Diplomonad (Giardia) Parabasalida (Trichomonas) IV. The Domain Eukarya Overview: Origin of the Eukarya C. Diversity of Eukarya

Trypanosoma IV. The Domain Eukarya Euglena Euglenozoa Overview: Origin of the Eukarya C. Diversity of Eukarya Euglena Euglenozoa

Apicomplexans (Plasmodium) Ciliates (Paramecium) Dinoflagellates Apicomplexans (Plasmodium) Ciliates (Paramecium) IV. The Domain Eukarya Overview: Origin of the Eukarya C. Diversity of Eukarya Alveolata

Diatoms IV. The Domain Eukarya Stramenopiles Brown Algae Overview: Origin of the Eukarya C. Diversity of Eukarya Stramenopiles Brown Algae

Radiolarians IV. The Domain Eukarya Foraminiferans Overview: Origin of the Eukarya C. Diversity of Eukarya Foraminiferans Rhizaria

IV. The Domain Eukarya Amoebozoa Overview: Origin of the Eukarya C. Diversity of Eukarya Amoebozoa

IV. The Domain Eukarya Red Algae Green Algae Plants Overview: Origin of the Eukarya Diversity of Eukarya Archaeplantae Red Algae Green Algae Plants

IV. The Domain Eukarya Overview: Origin of the Eukarya Diversity of Eukarya Archaeplantae

IV. The Domain Eukarya Opisthokonts Overview: Origin of the Eukarya C. Diversity of Eukarya Opisthokonts

IV. The Domain Eukarya FUNGI Chytrid zoospores flagella Overview: Origin of the Eukarya Diversity of Eukarya Opisthokonts FUNGI Chytrid zoospores flagella

IV. The Domain Eukarya Choanoflagellates Overview: Origin of the Eukarya Diversity of Eukarya Opisthokonts Choanoflagellates

IV. The Domain Eukarya ANIMALS Overview: Origin of the Eukarya Diversity of Eukarya Opisthokonts ANIMALS