Evidence forEvolution

Direct Instruction

then synthesis on 24R

EVOLUTION = Change over Time

=Descent With Modification=Adaptation of a species

Takes Place Over Long Periods of Time

-usually millions of years

Descent With Modification

Species Today Look Different From Their Ancestors

Each Living Species Has-Descended-With Changes-From Other Species-Over Time

Descent With Modification

Implies

All Living Organisms Are Related

Single Tree of Life

DNA, Body Structures, Energy Sources

Common Descent

All Species, Living (Extanct) & Extinct, Were Derived From Common Ancestors

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Descent With Modification: An Example

Evidence of Evolution

1. Fossil Record2. Comparative Anatomy3. Comparative Embryology4. Comparative Biochemistry5. Comparative Biogeography

Evidence of Evolution—1. The Fossil Record

• Evidence of orderly change can be seen when fossils are arranged according to their age.

Derived Traits vs. Ancestral Traits

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Evidence for Evolution – The Fossil RecordEvidence for Evolution – The Fossil Record

Evidence of Evolution—2. Comparative Anatomy

• Anatomy has different functions but constructed of similar bones in similar way.

• Evo predicts that modifications of ancestral body parts are more likely than formation of entirely new parts

2 Kinds:

Homologous Structures: same structures/different functions

Analogous Structures: different structures/same functions

an analogy= a comparison using like or as (this snake tastes like chicken, but is it?)

Homologous Structures • Structures in different organism that

indicate a shared ancestry–Check out these vertebrate forelimbs.

Homologous StructuresHomologous Structures

Analogous Structures

• Different Structures in different organisms that have a common function.

–Check out these flying machines.

Type of Homologous StructureVestigial Structures • Reduced or nonfunctional structures

• provide evidence of an organism’s evolutionary history.

http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html

5 min, 9 sec

Whale Evolution

Video

Ex of vestigial structures

Similarities In Embryonic Development

Evidence of Evolution—3. Comparative Embryology

Human Fetus – 5 weeks

http://www.pbs.org/wgbh/evolution/library/04/2/l_042_02.html

Comparative Embryology

Shows common ancestry

Video:

Proteins (Amino Acid) • MORE differences in AA sequences of distant

related species• LESS differences = species that are more

closely related.Nucleic Acids • MORE differences in DNA sequences of

distant related species• LESS differences = species that are more

closely related.

Evidence of Evolution—4. Comparative Biochemistry

Similar DNA = Similar AA = Similar Organisms

Which is more related to the human,

the snake or the tuna?

Different Species On Different Continents Have Similar Adaptations due to similarities of the Environments

Evidence of Evolution—5. Comparative Biogeography

• Organisms from different land masses look similar

• The most recent common ancestor is those of the same geographical region.

• But, the similar comparative anatomy demonstrates a distant common ancestor before the land masses separated.

ElephantsElephantsEx of a species with a common ancestor that became geographically isolated over 5.5 MYA from others in their species and then continued to evolve.

And the evolution was convergent –Becoming the African and Asian Elephants we know today.

Asian African

Evidence of Evolution

1. Fossil Record2. Comparative Anatomy3. Comparative Embryology4. Comparative Biochemistry5. Comparative Biogeography