BIO SCI 94 Chapter 25: Evolution by Natural Selection & Graphs
Course CodeBIO SCI 94
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Lesson 2 - Chapter 25: Evolution by Natural Selection + Bioskill 3: Graphs!
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!
the pattern component summarizes observations about the surrounding world!•
the process component is the mechanism that produces that pattern!•
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!
the theory that species change through time and come from a common •
this idea was started by Lamrack (not Darwin)!◦
he said evolution is progressive in making more complex and ◦
it consists of individuals of the same species that are living in the same area at the same time!•
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!◦
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 ◦
Sedimentary Rocks help diﬀer 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
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!◦
a branching diagram that describes the ancestor-descendant relationships •
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