EVOLUTION

http://www.youtube.com/watch?v=lhTSfOZUNLo

http://www.youtube.com/watch?v=HU4xmWwYA2A

Early Theories on Land

Oparin’s Primordial Soup – energy from sun, lightning, and heat; chemical reaction formed life in water, life emerged

The Big Bang Theory – lightning and gases

Intelligent Design The Alien Theory

Early Theories on Life Spontaneous

Generation Disproved by F. Redi Meat and Maggots

Experiment People still believed

microorganisms spontaneously generated

Pasteur’s experiment provided final proof of biogenesis

What data do we have?

Fossils: Trace – indirect, footprints Casts – rocks filled in

space of decayed animal

Molds – organism decays into sediment

Petrified – minerals replace organism

Amber/Frozen – trapped in ice

Determine environment

Determine species Habitat Diet Size Shape

Use of Fossils by Paleontologists

Endosymbiotic Theory

Aerobic bacteria are highly efficient at producing ATP

Early organisms engulfed aerobic bacteria

Bacteria “evolved” into mitochondria

Proof: mitochondria contain their own DNA and ribosomes

Aerobic bacteria

Ancient Prokaryotes

Ancient Anaerobic Prokaryote

Primitive Aerobic Eukaryote

Primitive Photosynthetic Eukaryote

Chloroplast

Photosynthetic bacteria

Nuclear envelope evolving Mitochondrion

Plants and plantlike protists

Animals, fungi, and non-plantlike protists

The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotes organisms. Ancient prokaryotes may have entered primitive eukaryotic cells and remained there as organelles.

Fossil Data for Evolution Homologous structures

Similar structure and function between species

Gorilla arms and human arms Analogous structures

Similar function but different structures

Bird wings and butterfly wings Vestigial structures

Structures that are no longer needed and are slowly fading out of society

Wisdom teeth, appendix

Homologous

Structures

Analogous Structures

Cassowary Whale pelvis and thigh bone

Mexican Blind Cave Fish

Human Vestigial Structures:

•erector pili are smooth muscle fibers that give humans “goose bumps

•Tailbone

•Wisdom teeth

•appendix

Evolutionary DataA body plan shared by vertebratesshows embryological development, suggesting common descent

Charles Darwin

Father was a doctor Worked towards a

degree in Theology 1831 HMS Beagle was

leaving to return slavesto South America

Darwin was hired as a naturalist to record information about nature

on the voyage

Galapagos Islands – coast of Ecuador Studied bird beaks and turtle size Returned to Europe Began writing On The Origin of

Species, a book about his research Darwin did not publish until another

scientist was about to publish similar work, Wallace (28 years later)

Darwin

Charles Darwin, last sentence of

On the Origin of Species

“There is a grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one: and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”

Adaptive Radiation

How does adaptive radiation work?

Natural Selection

Genetic variation among species Environmental challenges Struggle to survive Survival of the fittest Traits best suited will increase in

the population

Examples of Natural Selection

Bacterial resistance to antibiotics

Insect resistance to pesticides Industrial melanism

Mimicry

Types of Natural Selection

Stabilizing Favors average individual Big spiders are easily spotted, little ones

can’t get food Directional

Favors one extreme population Long bird beaks get more food when supply

is low Disruptive

Both extremes selected for Dark, medium, and light colored fish –

medium fish is seen in both environments

Directional Selection

Directional Selection

Food becomes scarce.

Key

Low mortality, high fitness

High mortality, low fitness

Stabilizing Selection

Key

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Birth Weight

Selection against both

extremes keep curve narrow and in same

place.

Low mortality, high fitness

High mortality, low fitness

Stabilizing Selection

Disruptive Selection

Disruptive Selection

Largest and smallest seeds become more common.

Nu

mb

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sin

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Beak Size

Population splits into two subgroups specializing in different seeds.

Beak Size

Nu

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f B

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sin

Po

pu

lati

onKey

Low mortality, high fitness

High mortality, low fitness

Artificial Selection

Speciation

Evolution of a new species

Geographic isolation Tree frogs in rainforest

Single population Divided by river Over time, two species

created and cannot interbreed

Behavioral Isolation

These meadowlarks have overlapping ranges, but do not interbreed because they have different mating songs.

Can you tell which one is the Eastern and which one is the Western Meadowlark?

Geographic Isolation