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?