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Lecture 3

Biology 1001A Lecture 3: Lecture 3- September 15, 2014

Course Code
BIOL 1001A
Tom Haffie

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September 15, 2014, 1
Lecture 3: Life on Earth
Origin of Species
-even more important than the idea of natural selection, Charles Darwin proposed the
idea of ‘Common Descent’
-this expressed that all things, if you went far enough back in evolutionary history,
shared a common ancestor ex. humans to fish, horses to cabbages
Similarities due to descent from a common ancestor
- Homolagies: traits shared by all forms of cellular
life on earth; shared because inherited from a
common ancestor
-Every organism has their genome in the form of
-Phospholipid bilayer is arranged in cells in
different organisms
-LUCA is the name given to the most recent
common ancestor to all species on Earth
How many species life on Earth and in the Ocean?
-unknown, we are constantly discovering new species at a rapid rate
-8.7 million species of eukaryotes including marine organisms(according to article)
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September 15, 2014, 2
-prokaryotes are not included because far more difficult to concentrate
-we have only named 1 million species on earth
-18000 new species have been discovered in the last calendar year
How far would we go to find the most common ancestor to all humans?
-based on average life time, average offspring of each female, average time of birth, it has
been estimated 3000 years
Reverse tour of Evolutionary History
-Branching points on tree of life> rendezvous points
-At each point, meet other species and the groupss MRCA
“Rendezvous Zero” MRCA of all humans
How far back in time do you think we would have to go to find?
-comparing DNA sequences
-A paper estimated 3000
years( estimated, so great
Rendezvous #1: Chimps
and Bonobos
-each chimps and bonobos are
equally related to humans
If we are descendants of the chimp, why are there still chimps around?
We are not descendants of the chimp! We just share a common ancestor!
Rendezvous #2: Gorillas
-Along with Chimps, Bonobos and Gorillas, we are considered African Great Apes
Rendezvous #3: Orang-utans
-Although still apes, not considered African Great Apes
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