11/10/2008
1
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
11/10/2008
2
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
11/10/2008
3
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/
11/10/2008
4
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…
11/10/2008
5
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
11/10/2008
6
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
11/10/2008
7
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…
11/10/2008
8
Evolution: Key Events
Evolution: Key Events
11/10/2008
9
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
11/10/2008
10
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