Mockingbirds

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- Mockingbirds Darwin began to think could the
variation WITHIN species eventually lead to
variation BETWEEN species?
Could organisms in a species become so different
that they become different species?
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C. Observations 4. Biogeography Island Fauna
s - How did these animals get here? Every
thing points to migration from Americas
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C. Observations 4. Biogeography Island Fauna
s - How did these animals get here? Every
thing points to migration - But if ancestors mi
grated from Americas,
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C. Observations 4. Biogeography Island Fauna
s - How did these animals get here? Every
thing points to migration - But if ancestors mi
grated from Americas, then the species must h
ave changed over time into the species we obs
erve there today. Because they are not the s
ame.
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C. Observations 5. Argument P1 Species that
are alive today are different from those that
have lived previously. (Fossil Record)

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C. Observations 5. Argument P1 Species that
are alive today are different from those that
have lived previously. P2 Spontaneous Generation
is refuted, so organisms only come from other
organisms. (Experimentation)
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C. Observations 5. Argument P1 Species that
are alive today are different from those that
have lived previously. P2 Spontaneous Generation
is refuted, so organisms only come from other
organisms. C1 Thus, the organisms alive today m
ust have come from those pre-existing, yet
different, species.
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C. Observations 5. Argument P1 Species that
are alive today are different from those that
have lived previously. P2 Spontaneous Generation
is refuted, so organisms only come from other
organisms. C1 Thus, the organisms alive today m
ust have come from those pre-existing, yet
different, species.
C2 There must have been change through time
(evolution).
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C. Observations 5. Argument P1 Species that
are alive today are different from those that
have lived previously. P2 Spontaneous Generation
is refuted, so organisms only come from other
organisms. C1 Thus, the organisms alive today m
ust have come from those pre-existing, yet
different, species.
C2 There must have been change through time
(evolution). Corollary The fossil record, vestig
ial organs, and homologies are all explicable and
logical in this context, and inexplicable (even
heretical) in some theological contexts
(imperfection).
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I. Darwins Contributions A. His Life B. Origi
n of Species C. Observations D. Hypothesis H
ow Change Occurs
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D. Hypothesis How Change Occurs
1. Transitional Observations
a. Domesticated Animals
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D. Hypothesis How Change Occurs
1. Transitional Observations
a. Domesticated Animals
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D. Hypothesis How Change Occurs
1. Transitional Observations
a. Domesticated Animals Humans can change the
characteristics of a species by selecting for
particular traits. This can lead to the
expression of extreme variation, well beyond the
original range of variation in the initial
group. Selection can create. There are no wolves
that are as small as Chihuahuas
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D. Hypothesis How Change Occurs
1. Transitional Observations
b. 1844 Darwin Reads Malthus - Essay On the
Principle of Population (1798)
Thomas Malthus (1766-1834)
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D. Hypothesis How Change Occurs
1. Transitional Observations
b. 1844 Darwin Reads Malthus - Essay On
Population P1 All populations have the capaci
ty to over-reproduce
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D. Hypothesis How Change Occurs
1. Transitional Observations
b. 1844 Darwin Reads Malthus - Essay On
Population P1 All populations have the capaci
ty to over-reproduce P2 Resources are finite
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D. Hypothesis How Change Occurs
1. Transitional Observations
b. 1844 Darwin Reads Malthus - Essay On
Population P1 All populations have the capaci
ty to over-reproduce P2 Resources are finite
C There will be a struggle for existence
most offspring born will die before reachin
g reproductive age.
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D. Hypothesis How Change Occurs
2. Natural Selection P1 All populations ha
ve the capacity to over-reproduce
P2 Resources are finite C There will be a st
ruggle for existence P3 Organisms in a p
opulation vary, and some of this
variation is heritable
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D. Hypothesis How Change Occurs
2. Natural Selection P1 All populations ha
ve the capacity to over-reproduce
P2 Resources are finite C There will be a st
ruggle for existence P3 Organisms in a populat
ion vary, and some of this variation is
heritable C2 Some organisms, as a consequence o
f their inherited traits, will be more likely to
survive and reproduce than others. There will be
differential reproductive success.
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D. Hypothesis How Change Occurs
2. Natural Selection C2 Some organisms, as
a consequence of their inherited traits, will be
more likely to survive and reproduce than others.
There will be differential reproductive
success. C3 So, adaptive traits will be pass
ed on in a population at higher frequency than
less adaptive traits. These adaptive traits will
accumulate in a population. The population will
change over time. LINEAGE EVOLUTION.
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D. Hypothesis How Change Occurs
2. Natural Selection C2 Some organisms, as
a consequence of their inherited traits, will be
more likely to survive and reproduce than others.
There will be differential reproductive
success. C3 Over time, adaptive traits will be
passed on in a population at higher frequency
than less adaptive traits. These adaptive traits
will accumulate in a population. The population
will change over time. LINEAGE EVOLUTION.
Corollary Two populations, adapting to
different environments, will become different
from one another perhaps so different that they
are unable to mate, and are different species
RADIATIONAL EVOLUTION.