The Diversity of Life

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

Ecological Roles Played By Prokaryotes The Diversity of Life I. A Brief History of Life A. Introduction ATMOSPHERE N fixation Photosynthesis Respiration BIOSPHERE Energy harvest of animals and plants Absorption Decomposition LITHOSPHERE

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

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.5 bya: Oldest Fossils

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.5 bya: Oldest Fossils Stromatolites - communities of layered 'bacteria'

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 2.3-2.0 bya: Oxygen in Atmosphere 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.5 bya: Oldest Fossils

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 The classical model of endosymbiosis explains the origin of eukaryotes as the endosymbiotic absorption/parasitism of archaeans by free-living bacteria.

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 0.7 bya: first animals 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

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 0.7 bya: first animals 2.0 bya: first eukaryotes 2.3-2.0 bya: Oxygen 0.5 bya: Cambrian 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.5 bya: Oldest Fossils

I. A Brief History of Life The Diversity of Life I. A Brief History of Life Introduction B. Timeline 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

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

I. A Brief History of Life 4.5 million to present The Diversity of Life I. A Brief History of Life Introduction B. Timeline 4.5 million to present (1/1000th of earth history) 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

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

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 Genus Felis Panthera Family Felidae Acinonyx Lynx 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 Genus Felis Panthera Family Felidae Acinonyx Lynx The Diversity of Life I. A Brief History of Life II. Classifying Life The Linnaean System 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.

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

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

III. The Prokaryote Domains: Eubacteria and Archaea 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 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. Oxygen Demand all eukaryotes require oxygen.

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 1. Responses to Oxygen: 2. Nutritional Categories: - chemolithotrophs: use inorganics (H2S, 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 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