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SBI3U1

The theory of evolution by natural
selection was proven by the following
methods:
1)Fossil
Record
2)Biogeography
3)Anatomy
4)Embryology
5)DNA
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Fossils are found within the
layers of sedimentary rock.
Specific fossils are found in
specific strata (rock layers).
Fossil groups are unique to each
stratum.
◦ paleontologists use this to determine
dates
A geological
time scale
Youngest
Fossils
(closest to the
surface)
Oldest
Fossils
Evidence from Fossil Record:
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Fossils within the younger layers are most
similar to species alive today.
Fossils appear in chronological order within
the sedimentary layers.
Not all organisms appear in the fossil record
at the same time.
Paleontologists have used fossils to trace the
evolution of the modern camel.
The Paleocene, Eocene,Oligocene, and Miocene
epochs are subdivisions of the Cenozoic era.
Scientists are always looking for transitional fossils
that show an intermediary link between past and present
groups of organisms.
Vestigial structures are reduced versions of what were
once functional structures in an ancestral species
Biogeography=Study of
geographical distribution of species
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1)Geographically close environments are more likely to
be populated by related species.
2)Animals found on islands often closely resemble
animals on the nearest continent.
3)Fossils of the same species can be found
on the coastlines of neighbouring continents
Notice that these vertibrates have the same
basic arrangement of bones but the bones
have different uses.
Human
Homologous structures = structures that have similar
structural elements and origin but may have a different
function. They originate from a common ancestor.
Ie. Limbs, hair
• Analogous structures= structures that do not have a
common evolutionary origin but perform similar
functions. These provide evidence for adaptation to suit
the environment.
Ie. the fins of a porpoise and a fish.
•
All of these organisms have a similar bone structure.
They were inherited from a common ancestor
Example: Insects,
Birds, and Bats all
have wings used for
flight (function) but
insects do not come
from a common
ancestor because
there are no bones.
*Note: Your textbook
describes bird and bat
wings as analogous, this is
NOT true.
Example: Penguins
and fish both has
fins for swimming.
The fin evolved as
a structural
adaptation, not
from a common
ancestor.
Both types of
squirrels have
evolved from
different
lineages
Elvis Fans
Have a
common
ancestor
(mother)
Evolved
from
separate
lineages
Sisters
Homology
Analogy
Embryology: the study of pre-birth stages of an
organism’s development
-used to determine evolutionary relationships between
animals:
Similarities in the
embryos of fish,
birds, and
mammals provide
evidence of
evolution of
species from a
common
ancestor.
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By comparing organisms’ genetic sequences,
scientists can determine their level of
similarity.
Two organisms with similar patterns of DNA,
suggests that they inherited this information
from a common ancestor.
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Read and make notes 8.2
Complete pg. 340 Q# 1- 3, 8-12