1/17/09


1


Basic
Evolu1on


Charles
Darwin


Served
as
naturalist
on
mapping
expedi1on
around
coastal
South
America.


Used
many
observa1ons
to
develop
his
ideas


Proposed
that
evolu1on
occurs
by




natural
selec+on


2


Voyage
of
the
Beagle


3


1/17/09


2


Charles
Darwin


evolu+on:

modifica1on
of
a
species
over
genera1ons



‐“descent
with
modifica1on”


natural
selec+on:

individuals
with
superior
physical
or
behavioral
characteris1cs
are
more
likely
to
survive
and
reproduce
than
those
without
such
characteris1cs


4


Darwin’s
Evidence


Similarity
of
related
species

‐
Darwin
no1ced
varia1ons
in
related
species
living
in
different
loca1ons


5


Darwin’s
Evidence


Popula1on
growth
vs.
availability
of
resources


‐popula1on
growth



is
geometric


‐increase
in
food


supply
is
arithme1c


6


1/17/09


3


Darwin’s
Evidence


Popula1on
growth
vs.
availability
of
resources


‐
Darwin
realized
that
not
all
members
of
a





popula1on
survive
and
reproduce.



‐Darwin
based
these
ideas
on
the
wri1ngs
of
Thomas
Malthus.


7


Post‐Darwin
Evolu1on
Evidence


Fossil
record
‐
New
fossils
are
found
all
the
1me


‐
Earth
is
older
than
previously
believed


Mechanisms
of
heredity


‐
Early
cri1cism
of
Darwin’s
ideas
were
resolved
by
Mendel’s
theories
for
gene1c
inheritance.


8


Post‐Darwin
Evolu1on
Evidence


Compara1ve
anatomy
‐
Homologous
structures
have
same
evolu1onary
origin,
but
different
structure
and
func1on.


‐
Analogous
structures
have
similar
structure
and
func1on,
but
different
evolu1onary
origin.


9


1/17/09


4


Homologous
Structures


10


Post‐Darwin
Evolu1on
Evidence


Molecular
Evidence


‐
Our
increased
understanding
of
DNA
and
protein
structures
has
led
to
the
development
of
more
accurate
phylogene+c
trees.


11