Transcript Evolutionary Evidence

Evolutionary Evidence
Evidence for Evolution
• 5 scientific disciplines:
1.
2.
3.
4.
5.
Paleontology
Biogeography
Embryology
Comparative anatomy
Molecular biology
Paleontology
• Fossil Record to reveal prehistoric existence of
extinct species
– Study changes of species or formation of new
species
• Dating to find the “age” of fossils
Fossil Record
• Fossils found in layers of sedimentary rock
– New layers form over old layers = creates record
over time
– Shows succession of organisms that populated
Earth over long periods of time
– Can determine “timeline” of fossils = relative
dating
Fossil Record
Dating
• Relative dating = using sedimentary rock to
find the relative “timeline” of organism
• Absolute dating = using radioactive isotope
decay (C-14) to determine the date of
organism
Uses
Hyracoidea
(Hyraxes)
Sirenia
(Manatees
and relatives)
• Fossil record used to
establish evolutionary
relationships and
descent with
modification
Moeritherium
Barytherium
Deinotherium
Mammut
Platybelodon
Stegodon
Mammuthus
Elephas maximus
(Asia)
Loxodonta
africana
(Africa)
Loxodonta cyclotis
(Africa)
34
24
Millions of years ago
5.5 2 1040
Years ago
Evolutionary Change in Horses
Evolution of Birds
• Archaeopteryx
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Lived about 150 mya
Links reptiles and birds
• Bony tail, teeth, and
feathers
Early Tetrapod
• 2006 Fossil Discovery
• Tiktaalik
•
Missing link from sea
to land animals
?
?
?
?
Biogeography
• Using geography to determine evolutionary
patterns
– Discovered: unrelated species have similar
characteristics when found in similar
environments
• Natural selection
Embryology
• Similar stages of development (ontogeny)
among related species
– Help with phylogeny
• All vertebrate embryos = similar structures at
different stages of development
– Gill slits, tail, etc.
Embryology
Gill slits
Post-anal tail
Chick embryo
Human embryo
Comparative Anatomy
• 2 kinds of structures that contribute to
identify evolutionary relationships among
species
– Homologous structures
– Analogous structures
Homologous Structures
• Similar characteristics resulting from common
ancestor
Homologous Structures
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•
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Similar structure
Similar developments
Different functions
Close evolutionary
relationship
– Common ancestor
Homologous Structures
Spines
Leaves
Succulent Leaves
Tendrils
Needles
Colored Leaves
Homologous Structures
• Some species have vestigial structures
– No longer serving a function
• Ex. snakes, whales, wings, appendix
Why would whales
have pelvis & leg bones
if they were always
sea creatures?
Analogous Structures
• Resemble other structures in different species
– Not because of common ancestor
Don’t be fooled
by their looks!
Analogous Structures
• Separate evolution of
structures
– Similar functions
– Similar external form
– Different internal
structure
– Different ancestors
Molecular Biology
• Comparing DNA and Protein Structure
– Universal genetic code: DNA & RNA
– Compare common genes
Human/kangaroo
Closely related species have
sequences that are more similar than
distantly related species
 DNA & proteins are a molecular record of
evolutionary relationships
Nucleotide substitutions
100
Dog/
cow
75
Human/
cow
Rabbit/
rodent
Llama/
cow
Horse/
donkey
50
Horse/cow
Sheep/
goat
25
Human/rodent
Pig/
cow
Goat/cow
0
0
25
50
75
Millions of years ago
100
125
Comparative Hemoglobin Structure
8
0 10
32 45
67
30
70
50
125
90
110 120
Number of amino acid differences between
hemoglobin (146 aa) of vertebrate species and that of humans
Molecular Biology
• Analysis of phenotypic and allelic frequencies
• Humans can select for “advantageous” traits
“descendants” of wild mustard
“descendants” of the wolf