BIO152H5 Lecture Notes - Lecture 9: Convergent Evolution, Chordate, Orangutan
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Evolution - Central Unifying Concept in
Biology
Lecture 9
Evolution:
Outline
Earth is Old
Evidence for change through time
– Extinctions
– Fossils, biogeographical, developmental,
and genetic/molecular evidence
Homology and vestigial traits
Analogy and convergent evolution
Earth is Ancient and has Evolved
• Geologic data show that Earth is ~ 4.6 byo
• fossil data show the earliest signs of life in rocks is
~ 3.4-3.8 byo
• earth's topography,
environment, and living
organisms have
changed drastically over
time
* planet and its
species are dynamic
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Pattern of Evolution
• Darwin described evolution as descent with
modification: change over time produced modern
species from ancestral species
• the theory of evolution by natural selection makes
two claims about the nature of species:
(1) species are related
(2) species change
Extinction
• many fossils provide evidence for extinct species
• not all fossils resemble living organisms
• many extinctions throughout earth’s history
• Darwin interpreted extinction as
evidence that species are
dynamic; if species have gone
extinct, then the array of species
living on Earth has changed
through time
Evidence for Change
Through Time
Fossils:
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Fossils: Transitional Forms
Darwin interpreted fossils as evidence that extinct forms and living forms are
related, that they represent ancestors and descendents
Descent With Modification
Darwin interpreted fossils
as evidence that extinct
forms and living forms
are related, that they
represent ancestors and
descendants
Fossil Evidence
Document Summary
Earth is ancient and has evolved: geologic data show that earth is ~ 4. 6 byo, fossil data show the earliest signs of life in rocks is. ~ 3. 4-3. 8 byo: earth"s topography, environment, and living organisms have changed drastically over time. Darwin interpreted fossils as evidence that extinct forms and living forms are related, that they represent ancestors and descendents. Darwin interpreted fossils as evidence that extinct forms and living forms are related, that they represent ancestors and descendants. Rhodocetus, about 47 myo traits that are intermediate between older and younger species. 1974 in ethiopia) provide evidence that the earliest human ancestors arose in africa. Homo habilis o g a s r a e y f o s n o i l l i. Using radiometric dating, scientists have estimated the age of fossil human ancestors. Humans are classified with apes because they share many biological characteristics.
