Evolution and Diversification of Life

OCN 201 Science of the SeaBiology Lecture 2

Frogfish

Grieg Steward (Oceanography) Office: CMORE Hale 121

Phone: x6-6775

Sunday, November 9, 2014

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

Sunday, November 9, 2014

• Heritability of traits from parent to offspring

• Variability among offspring (mutations, recombination)

• Over-production of offspring

• Selection by the environment: Individuals with favorable traits will survive and reproduce more

Basis of Evolution by Natural Selection

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Biological Diversity Arises through Selection

This is not “just a theory”. It is a fact.

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Incomplete Species Separations

donkeyhorse

muleSunday, November 9, 2014

Incomplete Species Separations

False Killer WhaleBottlenose Dolphin

“Keikaimalu”

= Wolphin

+

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Missing Links

Sunday, November 9, 2014

Missing Links

Discovered 2008 (Matt Friedman)

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• Prokaryotes (no nucleus)

• Bacteria

• Archaea

• Eukaryotes (with nucleus

A Fundamental Division

DNA

DNA

DNA

and other internal compartments)

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PhotosyntheticEukaryote

• Eukaryotes arose through the merger of multiple prokaryotic cells

Serial Endosymbiosis Theory

Eukaryote

Animals

PhotosyntheticBacteria

Plants

Archaea

Anaerobic Bacteria

AerobicBacteria

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Origins of Animals

Unicellular

Colonial

Multicellular

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Origins of Plants

Unicellular

Colonial

Multicellularmarine alga terrestrial moss

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Protista

Prokaryotae

Single CellEukaryotes

Prokaryotes

MulticellularEukaryotes

Animalia

Plantae Fungi

The Traditional Five Kingdoms

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Life is a Messy BusinessSymbioses and Horizontal Gene transfer Contribute to the Diversity We See

It is a web of life as much as a tree of life

Sunday, November 9, 2014

Evolution

• Evolution is not uni-directional

• Simple things came first

• Complexity accumulates slowly through trial and error via many known mechanisms

• The simple and the complex continue to co-exist

• As the earth changes, species die off and new ones emerge

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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

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Hierarchical Classification

• Species

• Genus

• Family

• Order

• Class

• Phylum

• Kingdom

• Domain

vulgaris

Octopus

Octopodidae

Octopoda

Cephalopoda

Mollusca

Animalia

Eukarya

Orcinus

orca

Delphinidae

Cetacea

Mammalia

Chordata

Animalia

Eukarya

delphis

Delphinus

Delphinidae

Cetacea

Mammalia

Chordata

Animalia

Eukarya

CommonOctopus

OrcaBottlenosedolphin

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Protista

Plantae

Animals

Fungi

The Old Five Kingdom View of Life

Monera

Macroscopic organisms

disproportionatelyrepresented

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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”

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Sequence ComparisonsDiversity and evolutionary relationships

Seq. A ATACGGTCAC..Seq. B ATTCGCTCAC..Seq. C ATGCGGTCAC..

A

C

B

1 22 G

A B CA 2 1B 2 2C 1 2

Pairwise comparisons of sequences to count nucleotide differences

Summarize differences in a distance matrix

Build tree which satisfies the observed distance relationships

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Eukaryota

The Three Domains of Life

Prokaryotes Eukaryotes

and two cell types

Domain

Domain Domain

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• 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

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Fossil Stromatolites Modern Stromatolites

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Timeline

First Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants 430

Mammals 190

Apes 7

Humans 2.5

You 0.00002

(millions of years ago)OrganismFirst appeared

Sunday, November 9, 2014