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Evolution and Diversification of Life
OCN 201 Science of the SeaBiology Lecture 2 The Handfish
-BBC Blue Planet
Evolution
Nothing in biology makes sense except in the light of evolution - Theodisius Dobzhansky
I am a creationist and an evolutionist. Evolution is God's, or Nature's method of creation. Creation is not an event that happened in 4004 BC; it is a process that began some 10 billion years ago and is still under way. - Theodisius Dobzhansky
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
Basis of Evolutionby Natural Selection
Evolution is not“just a theory”
Incomplete Separations
donkeyhorse
mule
64 chromosomes62 chromosomes
Incomplete Separations
False Killer WhaleBottlenose Dolphin
Wolphin
Pseudorca crassidens
Tursiops truncatus
PohaikealohaKawili Kai
Missing Links
Discovered2006
Missing Links
Discovered 2008 (Matt Friedman)
Protists
Plants
Animals
Fungi
The Old Five Kingdom View of
Life
Monera
Macroscopic organisms
disproportionatelyrepresented
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”
Sequence ComparisonsDiversity and evolutionary relationships
Seq. A ATACGGTCAC..Seq. B ATTCGCTCAC..Seq. C ATGCGGTCAC..
A
C
B
Distance matrix can then be used to build aphylogenetic tree
1 2
2 G
A B C
A 2 1
B 2 2
C 1 2
Eukaryota
The Three Domains of Life
Prokaryotes Eukaryotes
The molecular view
Prokaryotes (no nucleus)
Bacteria
Archaea
Eukaryotes (with nucleus
A Fundamental Division
DNA
DNA
DNA
and other internal compartments)
PhotosyntheticEukaryote
Eukaryotes arose through the merger of multiple prokaryotic cells
Serial Endosymbiosis Theory
Eukaryote
Animals
PhotosyntheticBacteria
Plants
Archaea
Anaerobic Bacteria
AerobicBacteria
Origins of Animals
Unicellular
Colonial
Multicellular
Origins of Plants
Unicellular
Colonial
Multicellularmarine alga terrestrial moss
Evolution
Simple things came first
Complexity is slowly added through trial and error via many mechanisms (mutation and symbiosis)
The simple and the complex continue to co-exist
Protista
Prokaryotae
Single CellEukaryotes
Prokaryotes
MulticellularEukaryotes
Animalia
Plantae Fungi
The Traditional Five Kingdoms
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 3.5 bya
First Evidence of Life
Fossil Stromatolites Modern Stromatolites
Timeline
First Prokaryotes >3500Photosynthetic Prokaryotes 2500Eukaryotes 1000Invertebrates 700Vertebrates 500Land Plants 430Mammals 190Apes 7Humans 2.5You 0.00002
(millions of years ago)OrganismFirst appeared
For much of the history of life on earth, life was microscopic
Questions?