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Chapter 25

BIO SCI 94 Chapter 25: Evolution by Natural Selection & Graphs


Department
Biological Sciences
Course Code
BIO SCI 94
Professor
Robin Bush
Chapter
25

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Lesson 2 - Chapter 25: Evolution by Natural Selection + Bioskill 3: Graphs!
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Learning Goals:!
25.1: The evolution of evolutionary though!
25.2: The pattern of evolution: species have changed and are related!
25.3: The process of evolution by natural selection!
25.4: Evolution in action: two case studies!
B.3: Reading graphs!
25.5: Common misconceptions!
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Scientific Theories!
the pattern component summarizes observations about the surrounding world!
the process component is the mechanism that produces that pattern!
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Old Theories of Evolution!
Plato came up with the idea that species are unchanging types and
that variations within species are unimportant!
this was called Typological Thinking!
Aristotle said species are fixed types and some species are more
complex and "better" than other!
!
Evolution!
the theory that species change through time and come from a common
ancestor!
this idea was started by Lamrack (not Darwin)!
he said evolution is progressive in making more complex and
"better species!
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Population!
it consists of individuals of the same species that are living in the same area at the same time!
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Population Thinking!
Darwin stated variations among individuals in a population were the key to understanding a species' nature!
determined that species change through time and species are related by a common ancestry!
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Evidence for Evolution!
traces of organisms, called Fossils, were found in the past were found!
the Fossil Record consists of all the fossils found on Earth!
scientists began putting the fossils by age and created a geologic time
scale!
Sedimentary Rocks help dier the layers of the Earth by age!
this scale indicated that the earth was roughly 4.6 billion years old
instead of the previously believed 6000 years old!
compared to the Extant Species ( species living today), 99% of all
species in the history of the Earth are Extinct, or no longer exists on
Earth!
there are Transitional Features that show the intermediate species between
ancestral and younger species!
the fact that these features are found at the appropriate time periods
between species proves the theory of evolution!
there are Vestigal Traits that are a reduced or incompletely developed
structure that has no function!
an example are tail bones in humans or leg bones in whales!
!
Phylogenetic Tree!
a branching diagram that describes the ancestor-descendant relationships
among species!
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