Transcript 2/19/13 Evidence for Evolution

Evidence for
Evolution
Evidence for Evolution

Adaptations: changes in a species that occur
over a long period of time that make a
species more successful in an ecosystem
Darwin’s Evidence for Evolution

Fossil Record

By comparing fossils from older rock layers to
fossils from newer rock layers, scientists can
document that life on earth has changed.
Fossils
Darwin’s Evidence of Evolution

Homologous Body
Structures


Features with a common
evolutionary origin
similar in arrangement
and/or function.
Darwin’s Evidence of Evolution

Analogous Structures: Have similar
arrangement and/or function but do not
have a common evolutionary origin.
Evidence for Evolution
Vestigial organs: Organ that doesn’t
serve a useful function anymore
 The presence of these organs may not
affect the organism’s ability to survive
 Natural selection will not eliminate that
organ

Examples of Vestigial Structures
Wings on flightless birds
 Eyes on blind fish
 The human appendix
 Hind leg bones on whales

http://www.pbs.org/wgbh/ev
olution/library/03/4/l_034_0
5.html
Darwin’s Evidence of Evolution

Similarities in
Embryology


Embryos of many
animals with a
backbone are very
similar
The same group of
embryonic cells
develop in the same
order and patterns in
all vertebrate
http://www.pbs.org/wgbh/evolution/library/04/2/l_042_02.html
BIOCHEMISTRY

By comparing DNA and RNA of different
species, we can determine their
relationships
http://www.pbs.org/wgbh/evolution/library/11/2/e_s_5.html