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Evolution: Diversification of LifeOCN201 Fall 2008OCN201 Fall 2008

Zackary JohnsonUniversity of Hawaii

Department of Oceanography

v20081110

Major Concepts• Evolution involves three processes

reproduction (heritability and over production)– reproduction (heritability and over‐production)– variation– “selection”

• Natural selection and genetic drift drive evolution• Not a linear or directed processE t t di it i lt f >3 5 billi f• Extant diversity is a result of >3.5 billion years of evolution

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Nothing in biology makes sense except in the light of evolution

‐Theodosius Dobzhansky

I am a creationist and an evolutionist. Evolution is God's or Nature's method ofEvolution 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. y‐ Theodosius Dobzhansky

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Evolution• Life has a history

• Different species share common ancestors

recent

http://evolution.berkeley.edu/

past

Phylogeny: “family tree”, or how organisms are related 

Evolution: descent with modification

• small scale changes (gene frequency in a population from one generation to another, “microevolution”)

l l h (d t f diff t i f• large scale changes (descent of different species from a common ancestor over many generations, “macroevolution”)

http://evolution.berkeley.edu/

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Evolution requires three processes:

• Reproduction (heritability and over‐production)

• Variation

• “Selection” (natural selection and genetic drift)

Evolution: Reproduction

• Heritability: traits are passed to offspring

– Recognized early in history, but Gregor Mendel (“father of ti ”) f li d it t d i (29 000!)genetics”) formalized its study using peas (29,000!) 

– 50 years later DNA indentified (Watson and Crick) as the carrier of genetic information

– Many many more details…

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Evolution: Reproduction• Over‐production: more offspring produced than survive to reproduce (typically)to reproduce (typically)

Evolution: Variation

• Offspring are not identical to parent or each other

• Mechanisms: 

Mutations: changes in the DNA caused by the– Mutations: changes in the DNA caused by the environment or the lack of 100% fidelity in replication

– Gene flow: movement of genes from one population to another (i.e. new genes or alleles (different forms of a gene)  introduced, or taken away)

Sex: new combinations of genes– Sex: new combinations of genes or alleles

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Evolution: “Selection”• Natural selection: favorable heritable traits become more common in successive generations of a population of reproducing organisms

~10,000 years (generations)

Evolution: “Selection”• Genetic Drift (allelic drift): accumulation of random events that change the makeup of a gene pool slightly, but often compound over time

N = 10

Iwi

N = 100

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Evolution: in process

Origin of Species, Darwin (1859)

God

Angels

Being

Being

Evolution is not directed (“trees not ladders”)

Demons

Man

Animals

ecom

ing

Realm of 

Plants

MineralsNon‐Being

Realm of B

e

Aristotle’s “Chain of being” Many  aborted paths…

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Evolution: Key Events

Evolution: Key Events

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Evolution: Key Events

Evolution: Timing of Key and Selected Events

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes >3500

Photosynthetic Prokaryotes 2500

Organism First Appearance (mya)

Prokaryotes

Photosynthetic Prokaryotesy y

Eukaryotes

Invertebrates

Vertebrates

Land Plants

Mammals

Aquatic(i.e. oceandominated)

y y

Eukaryotes

Invertebrates

Vertebrates

Land Plants

Mammals

y y

Eukaryotes 1000

Invertebrates

Vertebrates

Land Plants

Mammals

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates

Land Plants

Mammals

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants

Mammals

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants 430

Mammals

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants 430

Mammals 190

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants 430

Mammals 190

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants 430

Mammals 190

y y

Eukaryotes 1000

Invertebrates 700

Vertebrates 500

Land Plants 430

Mammals 190

y y

Eukaryotes

Invertebrates

Vertebrates

Land Plants

Mammals

Apes

Humans

You

Most of evolution (historically) occurred in the oceansOrganisms that we are familiar with (higher organisms) are relatively recent

Apes

Humans

You

Apes

Humans

You

Apes

Humans

You

Apes

Humans

You

Apes

Humans

You

Apes

Humans

You

Apes 7

Humans

You

Apes 7

Humans 2.5

You

Apes 7

Humans 2.5

You 0.00002

Apes

Humans

You

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Major Concepts• Evolution involves three processes

reproduction (heritability and over production)– reproduction (heritability and over‐production)– variation– “selection”

• Natural selection and genetic drift drive evolution• Not a linear or directed processE t t di it i lt f >3 5 billi f• Extant diversity is a result of >3.5 billion years of evolution