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
ATMOSPHERE
A. Introduction
N fixation
Photosynthesis
BIOSPHERE
Absorption
LITHOSPHERE
Respiration
Energy harvest of
animals and
plants
Decomposition
The Diversity of Life
I. A Brief History of Life
4.5 bya: Earth Forms
A. Introduction
B. Timeline
The Diversity of Life
I. A Brief History of Life
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
A. Introduction
B. Timeline
The Diversity of Life
I. A Brief History of Life
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
A. Introduction
B. Timeline
The Diversity of Life
I. A Brief History of Life
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
A. Introduction
B. Timeline
Stromatolites - communities of layered 'bacteria'
2.3-2.0 bya: Oxygen in
Atmosphere
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
The Diversity of Life
I. A Brief History of Life
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
A. Introduction
B. Timeline
Grypania spiralis – possibly
a multicellular algae, dating
from 2.0 by
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
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
- 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
0.7 bya: first animals
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
0.7 bya: first animals
0.5 bya: Cambrian
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
0.7 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
0.7 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya: Cenozoic
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
0.7 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya: Cenozoic
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
4.5 million to present
A. Introduction
B. Timeline
(1/1000th of earth
history)
For ~40% of life’s history, life was
exclusively bacterial
0.7 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya: Cenozoic
2.3-2.0 bya: Oxygen
2.0 bya: first eukaryotes
3.5 bya: Oldest Fossils
4.0 bya: Oldest Rocks
4.5 bya: Earth Forms
The Diversity of Life
I. A Brief History of Life
A. Introduction
B. Timeline
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
Genus Felis
A. The Linnaean System
- a ‘nested’ hierarchy
based on morphology
Acinonyx
Lynx
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
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
The Diversity of Life
I. A Brief History of Life
II. Classifying Life
Genus Felis
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.
Acinonyx
Lynx
Panthera
Family Felidae
The Diversity of Life
I. A Brief History of Life
II. Classifying Life
Genus Felis
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.
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.
OLD
NEW
HOMINIDAE
PONGIDAE
Genera:
Australopithecus
Homo
Genera:
Pan
Gorilla
Pongo
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
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Class: Mammalia
Class: Aves
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
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
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
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 X’some
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.
III. The Prokaryote Domains: Eubacteria and Archaea
A. 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
A. Overview
B. Metabolic Diversity of the Prokaryotes
1. Oxygen Demand
all eukaryotes require oxygen.
III. The Prokaryote Domains: Eubacteria and Archaea
A. 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
A. 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
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