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Lecture 5

BIOL 215 Lecture Notes - Lecture 5: Heterotroph, Parallel Evolution, Polyphyly

Course Code
BIOL 215
Neil Price

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Evolutionary History and Multicellularity
Historical setting
-Until 18th century, western culture believed:
-Species never change
-The Earth was only thousands of years old
-There were no extinctions since fossils were representations of species who
were still alive.
-Any adaptation in species was caused by God
-When Darwin published his book in 1858, these beliefs were altered. People now
believed that:
-The Earth was actually more than 300 m.y old
-Fossils represented extinct species
-Organisms inherit traits from ancestors
-Species change (but mechanism was still unknown)
-Adaptation is a result of natural selection (not divine intervention)
-When Darwin explored the Galapagos Islands, he discovered that the species varied
from island to island even in such close proximity to each other. Each island had a
unique version of finches, and turtles, and other animals.
Darwin’s Evolutionary Theory
-Organisms are always in competition for resources. This was the main idea behind
natural selection.
-Those who survive are said to have more favourable features than competitors,
allowing them to pass off these features through genes to their offspring.
Artificial Selection
-Breeders select desirable traits and breed through generations until those traits are
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