Evolution

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Evolution

• Diversity of Life

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Evolution
Nothing in biology makes sense EXCEPT in the
light of evolution. Theodosius Dobzhansky
Charles Darwin in later years
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Theory of Evolution Today

• Supporting Evidence

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Homologous Structures
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Evidence for Evolution - Comparative Embryology
Similarities In Embryonic Development
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Similarities in DNA Sequence
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Evolution of pesticide resistance in response to
selection
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Evidence for Evolution Evolution Observed
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Evidence for Evolution Evolution Observed
Selection against small guppies results in an
increase in average size
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Evolutionary Time Scales
Macroevolution Long time scale events that
create and destroy species.
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Evolutionary Time Scales
Microevolution Short time scale events
(generation-to-generation) that change the
genotypes and phenotypes of populations
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Evidence of Evolution

• Key Concept
• Darwin Argued That Living Things Have Been
  Evolving On Earth For Millions of Years. Evidence
  For This Process Could Be Found In
• The Fossil Record
• The Geographical Distribution of Living Species
• Homologous Structures of Living Organisms
• Similarities In Early Development

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Fossil Record

• Earth is Billions of Years Old
• Fossils In Different Layers of Rock (sedimentary
  Rock Strata) Showed Evidence Of Gradual Change
  Over Time

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Geographic Distribution of Living Species

• Different Animals On Different Continents But
  Similar Adaptations To Shared Environments

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Homologous Body Structures

• Scientists Noticed Animals With Backbones
  (Vertebrates) Had Similar Bone Structure
• May Differ In Form or Function
• Limb Bones Develop In Similar Patterns
• Arms, Wings, Legs, Flippers

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Homologous Body Structures

• Structures That Have Different Mature Forms But
  Develop From The Same Embryonic Tissues
• Strong Evidence That All Four-Limbed Animals With
  Backbones Descended, With Modification, From A
  Common Ancestor
• Help Scientist Group Animals

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Homologous Body Structures
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Homologous Body Structures

• Not All Serve Important Functions
• Vestigial Organs
• Appendix In Man
• Legs On Skinks

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Similarities In Early Development

• Embryonic Structures Of Different Species Show
  Significant Similarities
• Embryo early stages of vertebrate development

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Human Fetus 5 weeks
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Chicken
Turtle
Rat
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Review
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Darwin's Theory

1. Individual Organisms In Nature Differ From One
   Another. Some Of This Variation Is Inherited
2. Organisms In Nature Produce More Offspring Than
   Can Survive, And Many Of These Offspring Do No
   Reproduce

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Darwin's Theory

1. Because More Organisms Are Produced Than Can
   Survive, Members Of Each Species Must Compete For
   Limited Resources
2. Because Each Organism Is Unique, Each Has
   Different Advantages Disadvantages In The
   Struggle For Existence

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Darwin's Theory

1. Individuals Best Suited To Their Environment
   Survive Reproduce Successfully Passing Their
   Traits To Their Offspring.
2. Species Change Over Time. Over Long Periods,
   Natural Selection Causes Changes That May
   Eventually Lead To New Species

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Darwin's Theory

1. Species Alive Today Have Descended With
   Modifications From Species That Lived In The Past
2. All Organisms On Earth Are United Into A Single
   Tree Of Life By Common Descent

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Early Human Phylogeny
The Hominid Family Tree                        
                                
                   

                   
mya millions of years ago        tya thousands of years ago mya millions of years ago        tya thousands of years ago mya millions of years ago        tya thousands of years ago mya millions of years ago        tya thousands of years ago mya millions of years ago        tya thousands of years ago
A -  Orrorin tugenensis(6 mya)
B -  Ardipithecus ramidus(4.4 mya)
C -  Australopithecus anamensis(4.2 to 3.9 mya)
D -  Australopithecus afarensis(3.6 to 2.9 mya)
E -  Kenyanthropus platyops(3.5 to 3.3 mya)
F -  Australopithecus africanus(3 to 2 mya)
G -  Australopithecus aethiopicus(2.7 to 2.3 mya)
H -  Australopithecus garhi(2.5 mya)
I -  Australopithecus boisei(2.3 to 1.4 mya)
J -  Homo habilis(2.3 to 1.6 mya)
K -  Homo erectus(1.8 to 0.3 mya)
L -  Australopithecus robustus(1.8 to 1.5 mya)
M -  Homo heidelbergensis(600 to 100 tya)
N -  Homo neanderthalensis(250 to 30 tya)
O -  Homo sapiens(100 tya to present)
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Homo erectus 200 mya-70 tya
Homo neaderthalensis 300-28 tya
Homo heidelbergensis 600-250 tya
H. floresiensis compared to modern human 95-13
tya
Australopithecene africanus 3-2.4 mya
Paranthopus boisei 2.6-1.2 mya