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 served
on the
HMS Beagle
that sailed on a
5 year
expedition
 his
job was to
collect, study, and
store biological
specimens
◦one of the locations was the
Galapagos Islands, west of South
America
 Darwin
collected
many species of finch
 he
hypothesized that
a few birds migrated
from the mainland
and adapted to the
different island
environments
1.
Hutton and Lyell
◦ came up with the idea of
gradualism, which explains how it
took long periods of time to
produce geographical features
Jean Baptiste
Lamarck
◦ one of the first
scientists to
recognize that
living things
have changed
over time
2.
1.
2.
3.
all organisms continually
change in order to reach
perfection
organisms can alter
their bodies by the
principle of use and
disuse
he claimed that acquired
characteristics could be
inherited
Thomas Malthus
◦ he stated in his essay The
Principle of Population that if
the human population continued to
grow, sooner or later there would
not be enough resources for
everyone
3.
Artificial selection (please add)
◦ Darwin observed how humans
could change organisms by
selection of specific traits
4.
 Darwin
was forced to
publish when another
scientist, Alfred
Wallace, came up with
a similar idea
 Darwin’s book, Origin
of Species, stirred up
controversy for the
next decade
Natural Selection
1. not all individuals survive when
competing for resources
(“struggle for existence”)
the individuals who survive
are best adapted to their
environment
(“survival of the fittest”)
◦ nature acts on the variation
within a population
2.
3.
after many
generations, the
population may
change to resemble
the best adapted
individuals
(“descent with
modification”)
1.
Fossils
◦ there should be intermediate
stages found in the fossil record
Anatomy
◦ homologous structures are
modified structures that show
common ancestry
2.
same on inside,
different on
outside
◦ analogous structures are
different in arrangement but
have a similar function
different on
inside, same on
outside
◦ vestigial
structures have
no current
purpose, but
may have
functioned in an
ancestor
Embryology
◦ similarities in embryo structure
suggest evolution from a common
ancestor
3.
Biochemistry
◦ DNA or amino
acid sequences
can be
compared to
see how
closely related
2 species are
4.
Concealing
coloration.
Disruptive
Coloration
Disguises
Counter
shading
Mimicry
 Select
one type of camouflage.
 Color/shade it just right.
 Place it in it’s habitat!
 variation
is the inheritable
differences within the
same species
 the gene pool is all of the
genes present in a population
 changes in the frequencies of
alleles is microevolution
a population is the smallest
unit that can evolve
◦
1. mutation
DNA
2. genetic
- a permanent change in
drift – chance events can
change the gene pools of small
populations
3.
4.
5.
migration of individuals into
and/or out of a population can
change allele frequencies
non-random mating (similar to
selective breeding; only certain
traits are desired)
natural selection
stabilizing selection
◦favors average individuals in a
population
1.
directional selection
◦favors one of the extreme forms
of a trait
2.
disruptive selection
◦individuals of both extreme forms
are favored over the average
3.
-
a species is a group of organisms
that can interbreed and produce
fertile offspring
Geographic isolation
◦ a physical barrier separates a
population into groups (organisms
adapt to their isolated
environment)
1.
Reproductive Isolation
◦ Occurs when organisms are
prevented from producing fertile
offspring
 occurs when mating behaviors/
times/seasons don’t match
 occurs when genetics aren’t
similar enough
2.
 mass
extinctions have wiped out a
large number of Earth’s history
Following
these mass
extinctions
new
species
arise
1. Darwin proposed
that evolution was a
slow, steady process
 small adaptive
changes accumulate
over time
 this idea is known as
gradualism
punctuated
equilibrium states
that speciation
occurs in relatively
quick bursts
◦ The bursts of
change are then
followed by long
periods of stability
2.
divergent evolution is the pattern
of evolution in which many
different species can be traced
back to a common (same) ancestor
◦ the different species adapted to
different environments
◦ this is also called adaptive
radiation
1.
Evolution often
happens among island
chains because there
are different
habitats
2.
convergent evolution occurs when
distantly related organisms evolve
similar traits