The Diversity of Life

I. A Brief History of Life II. Classifying Life III. The Prokaryotic Domains

The Diversity of Life I. A Brief History of Life A. Introduction ATMOSPHERE BIOSPHERE LITHOSPHERE N fixationPhotosynthesisRespiration DecompositionAbsorption Energy harvest of animals and plants Ecological Roles Played By Prokaryotes

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils Stromatolites - communities of layered 'bacteria'

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen in Atmosphere

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotesGrypania spiralis – possibly a multicellular algae, dating from 2.0 by

The classical model of endosymbiosis explains the origin of eukaryotes as the endosymbiotic absorption/parasitism of archaeans by free-living bacteria. The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline

The Diversity of Life I. A Brief History of Life A.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

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotes0.7 bya: first animals

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotes0.5 bya: Cambrian0.7 bya: first animals

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotes0.5 bya: Cambrian0.24 bya:Mesozoic0.7 bya: first animals

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotes0.5 bya: Cambrian0.24 bya:Mesozoic0.7 bya: first animals0.065 bya: Cenozoic

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotes0.5 bya: Cambrian0.24 bya:Mesozoic0.7 bya: first animals0.065 bya: Cenozoic 4.5 million to present (1/1000th of earth history)

The Diversity of Life I. A Brief History of Life A.Introduction B. Timeline 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.5 bya: Oldest Fossils bya: Oxygen 2.0 bya: first eukaryotes0.5 bya: Cambrian0.24 bya:Mesozoic0.7 bya: first animals0.065 bya: Cenozoic For ~40% of life’s history, life was exclusively bacterial

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

The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System - a ‘nested’ hierarchy based on morphology Genus Felis Panthera Family Felidae Acinonyx Lynx

The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.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

Genus Felis Panthera Family Felidae Acinonyx Lynx The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.Cladistics and Phylogenetic Systematics But there are inconsistencies to correct: Cougar (Felis concolor) is in the genus Felis but is biologically more closely related to Cheetah (which are in another genus), than to other members of the genus Felis. The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group.

Genus Felis Genus Panthera Family Felidae * * The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.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. Now, all members of the genus Felis share one common ancestor.

The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.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 Genera: Pan Gorilla Pongo OLD

The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.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. Phylum: Chordata Subphylum: Vertebrata Class: Reptilia Class: Mammalia Class: Aves OLD

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

The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.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

NEW The Diversity of Life I. A Brief History of Life II. Classifying Life A.The Linnaean System B.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.

III. The Prokaryote Domains: Eubacteria and Archaea A.Overview

III. The Prokaryote Domains: Eubacteria and Archaea A.Overview “Horizontal Gene Transfer” complicates phylogenetic reconstruction in prokaryotes and dating these vents by genetic similarity and divergence.

III. The Prokaryote Domains: Eubacteria and Archaea A.Overview BacteriaArchaeaEukarya No nucleusno nucleusnucleus no organelles organelles peptidoglycanno 1 RNA Polyseveral F-methioninemethionine Introns rarepresentcommon No histoneshistones Circular X’some Linear X’some

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

III. The Prokaryote Domains: Eubacteria and Archaea A.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.

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 A.Overview B. Metabolic Diversity of the Prokaryotes

III. The Prokaryote Domains: Eubacteria and Archaea A.Overview B. Metabolic Diversity of the Prokaryotes 1. Oxygen Demand all eukaryotes require oxygen.

1. Responses to Oxygen: all eukaryotes require oxygen. bacteria show greater variability: - obligate anaerobes - die in presence of O 2 - aerotolerant - don't die, but don't use O 2 - facultative aerobes - can use O 2, but don't need it - obligate aerobes - require O 2 to live III. The Prokaryote Domains: Eubacteria and Archaea A.Overview B. Metabolic Diversity of the Prokaryotes

1. Responses to Oxygen: 2. Nutritional Categories: - chemolithotrophs: use inorganics (H 2 S, etc.) as electron donors for electron transport chains and use energy to fix carbon dioxide. Only done by bacteria. - photoheterotrophs: use light as source of energy, but harvest organics from environment. Only done by bacteria. - photoautotrophs: use light as source of energy, and use this energy to fix carbon dioxide. bacteria and some eukaryotes. - chemoheterotrophs: get energy and carbon from organics they consume. bacteria and some eukaryotes. III. The Prokaryote Domains: Eubacteria and Archaea A.Overview B. Metabolic Diversity of the Prokaryotes

III. The Prokaryote Domains: Eubacteria and Archaea A.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