Evolution and Diversification of Life
Transcript of Evolution and Diversification of Life
Evolution and Diversification of Life
OCN 201 Science of the Sea Steward
Biology Lecture 2The Handfish
-BBC Blue Planet1
2Phytoplankton Bacteria Viruses
Plankton Ecology
Grieg Steward, Professor Department of Oceanography
Plankton Ecology
When do you think life began?
A: > 3 billion years ago
B: about 6000 years ago
C: < 2000 years ago
D: around 1990
E: I’m still waiting
First Evidence of Life
4
‣ Earth formed about 4.5 billion years ago (bya) and crust solidified 4.1 bya
‣ Mineral deposits, thought to be produced only by biological activity, dated at 3.8 bya
‣ Fossils resembling present-day mats of marine microorganisms found at about 3.5 bya
5
Fossil Stromatolites Modern Stromatolites
Multicellular Lifeanimals, plants, fungi
Complexity appears gradually over timeEvolutionary History of Life
6
BACTERIA & ARCHAEA
Prokaryotes Eukaryotes
EUKARYA
single-cellProtists
TIME
Protocell
photosynthesisevolves
colonial
A Fundamental Division
DNA
DNA
DNA
and other internal compartments7
‣ Prokaryotes (no nucleus)
• Bacteria
• Archaea
‣ Eukaryotes (with nucleus…)
….and other internal compartments
The Origins of the Eukaryotic Cell TypeSerial Endosymbiosis Theory
8
Plants
Animals
Lynn Margulis
Pick the Prokaryote
B
D E
CA
Origins of Life
Not sure exactly how first self-replicating cell came into existence over 3.5 billion years ago
But once it did, it would be immediately subject to the process of evolution by natural selection
10
Basis of Evolution by Natural Selection
Heritability of traits from parent to offspring
Variability among offspring (mutations, recombination)
Over-production of offspring
Selection by the environment: More individuals with favorable traits will survive and reproduce than those with unfavorable traits
11
When was the Theory of Evolution by Natural Selection first publicly presented?
A: 1776
B: 1858
C: 1903
D: 1918
E: 1982
…at the Linnean Society of London
Whose ideas were presented?
A: Charles Darwin
B: Alfred Russel Wallace
C: David Lee Roth
D: A &B
E: None of the above
On The Tendency of Varieties to Depart Indefinitely from the Original Type - Alfred Russel Wallace
On the Origin of Species - Charles Darwin
14
Natural SelectionEvolution is not “just a theory”
Artificial Selection
Natural Selection
Incomplete Separations
15
donkeyhorse
mule or hinny
Up to a two line subtitle, generally used to describe the takeaway for the slide
Incomplete Separations
16
False Killer WhaleBottlenose
Dolphin
Wolphin
Keikaimalu
Pseudorca crassidens
Tursiops truncatus
Missing Links
17
Discovered2006
Missing Links
18
Discovered 2008 (Matt Friedman)Transitional flatfish fossils
Classification of Life
The vast diversity of life makes sense when considered in the light of evolutionary history
The splitting of one species into two leads to a nested hierarchy of characteristics that can be shown as a branching tree
19
The Old Five Kingdom View of Life
20
Prokaryotes
Protists
FungiPlants Animals
Multi-CellularEukaryotes
Single-CellEukaryotes
Prokaryotes
Incr
easi
ng C
ompl
exity
w
ith t
ime
New Understanding of the Diversity of Life
Early work relied on morphological differences - thus a focus on plants and animals
The evolutionary history of microbes was unclear
Molecular evidence (DNA Sequences) generally confirmed fossil evidence, but also revealed the deep history of the microbial world
21
Morphology vs DNA sequences
compared to the very large genetic differences among bacteriaAll animals are quite closely related
22
Look different, but close relatives Look similar, but very distance relatives
Florida Sea Grant Extension
Grieg Steward
Getty
The History of an Organism is Written in its DNA
• But how do we interpret it?
• Can use changes in DNA sequence over time as a “molecular clock”
23
Sequence ComparisonsDiversity and evolutionary relationships
Seq. A ATACGGTCAC..Seq. B ATTCGCTCAC..Seq. C ATGCGGTCAC..
1 2
2 G
A B C
A
B
C
A C BDistance matrix can then
be used to build aphylogenetic tree
22
1
1
22
PlantsAnimals
Diversification of LifeBACTERIA EUKARYAARCHAEA
PhagotrophyNew mode of consumption
by engulfment
Photosynthesis
DOMAIN
Prokaryotes EukaryotesCELL TYPE
LUCA ?Last Universal Common Ancestor
Protists
Key Points
• Evolution is not uni-directional…but
• Simple things came first - complexity accumulates slowly through trial and error via many known mechanisms
• Eukaryotes arose through Serial Endosymbiosis
• The simple and the complex continue to co-exist
• As the earth changes, species die off and new ones emerge