The Diversity of Life

1
The Diversity of Life
2
The Diversity of Life I. A Brief History of Life
II. Classifying Life
III. The Prokaryotic Domains
3
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
Decomposition
Absorption
LITHOSPHERE
4

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

4.5 bya Earth Forms
5

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

4.5 bya Earth Forms
4.0 bya Oldest Rocks
6

• 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
7

• 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'
8

• 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
9

• 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
10

• 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.
11

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

12

• 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
13

• 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
14

• 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 byaMesozoic
4.5 bya Earth Forms
4.0 bya Oldest Rocks
3.5 bya Oldest Fossils
15

• 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 byaMesozoic
4.5 bya Earth Forms
4.0 bya Oldest Rocks
3.5 bya Oldest Fossils
16

• 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 byaMesozoic
4.5 bya Earth Forms
4.0 bya Oldest Rocks
3.5 bya Oldest Fossils
17

• 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 byaMesozoic
4.5 bya Earth Forms
4.0 bya Oldest Rocks
3.5 bya Oldest Fossils
For 40 of lifes history, life was exclusively
bacterial
18

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

19

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

20

• 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

21

• 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.

22

• 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.

23

• 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.

24

• 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
25

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

NEW
26

• 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
27

• 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
28

• III. The Prokaryote Domains Eubacteria and
  Archaea
• Overview

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• 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.

30

• III. The Prokaryote Domains Eubacteria and
  Archaea
• Overview

Bacteria Archaea Eukarya
No nucleus no nucleus nucleus
no organelles no organelles organelles
peptidoglycan no no
1 RNA Poly several several
F-methionine methionine methionine
Introns rare present common
No histones histones histones
Circular Xsome Circular Xsome Linear Xsome
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• 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.

32

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

33

• 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.

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• 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.
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• III. The Prokaryote Domains Eubacteria and
  Archaea
• Overview
• B. Metabolic Diversity of the Prokaryotes

1. Oxygen Demand all eukaryotes require oxygen.
36

• 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
37

• 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.
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• 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

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Bacteria still drive major dynamics of the
biosphere