Transcript Evidence of Evolution

Artificial Selection aka Selective Breeding
 Darwin noted that plant and animal breeders would breed
only the largest hogs, the fastest horses, or the cows that
produced the most milk.
 Darwin termed this process artificial selection or selective
breeding.
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Evidence of Evolution
Darwin argued that living things have
been evolving on Earth for millions
of years. Evidence for this process
include:
1. Fossils
2. Comparative anatomy
3. Biochemistry of different life forms
Fossil Evidence
 Paleontology: Study of the
fossil record.
 Fossils: Remains or traces of
organisms that lived in past
ages, to understand past life
forms.
Fossil Evidence
 By comparing fossils from
older rock layers with fossils
from younger layers, scientists
could document that life on
Earth has changed over time.
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Fossil Evidence in sedimentary rock
Fossil Evidence
 Some scientists have found
transitional fossils.
 Transitional fossils: Show a
transition from one species to
another.
 For example: Whales
Transitional Fossils of Whales
• Older whales were hoofed
mammals that lived on land.
• These animals were able to
walk on land and swim.
• Later, fossils suggest that over
time, the hind limbs of the
whales’ ancestors shrank.
• Their forelimbs became
flippers.
• Their hind limbs became a tail
called a fluke.
Comparative Anatomy/Physical Features:
Homologous Structures
Body parts of different
organisms that have a
similar structure but may
have different functions.
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Comparative Anatomy: Homologous
Structures
Composed of similar bones. Must mean they all shared an
ancestor that had a similar structure.
Comparative Anatomy: Analogous
Structures
Analogous Structures
 Body parts that have a similar
function but not a similar
structure.
 They do not indicate shared
ancestry.
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Comparative Anatomy: Analogous
Structures
Bird wing and butterfly wing
Comparative Anatomy: Vestigial Structures
Vestigial Structure:
A body part that does not
seem to play a major role in
an organism’s life functions
but was more important in
the organism’s ancestors.
Rats also have an appendix
suggesting we share a
common ancestor.
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Comparative Anatomy: Embryology
Embryology: Study of embryos.
Embryo: Early stage of development in an organism.
Embryos of related organisms develop in similar ways.
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
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Human embryo
Biochemical Evidence of Evolution
 Recall that all organisms contain the nucleic acid:
DNA.
 DNA directs the production of proteins which are
made of amino acids.
 The more similar an amino acid sequence is, the
more closely related organisms are and most likely
shared an ancestor.
 We can compare hemoglobin: a protein found in
RBC’s to determine this.
Biochemical Evidence
Biochemical Evidence
 In addition to hemoglobin,
Cytochrome C is another
protein that determines
how closely related species
are to one another.