Download Evidences for Evolution

Evidences for Evolution
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Fossils and Geologic Time
Comparative Anatomy
Biogeography
Molecular Biology
Comparative Embryology
Geologic Time
•  Uniformitarianism
provides evidence that the
earth is very old.
•  Provides support for
evolution based on the fact
that there has been time
for evolution to occur.
•  Geology and evolution are
closely tied.
•  Use relative dating to
estimate ages of rocks.
•  Use radiometric dating to
determine specific rock
age.
Fossils
•  Evidence for change in
organism anatomy over
time.
•  Evidence for the type of
environment that once
existed.
•  Indicates global climate
change.
•  Fossil record is somewhat
incomplete. Very clear
evidence for horse,
elephant, clam and snail
evolution.
More fossils
•  Transitional fossils:
amphibians and fish,
birds and reptiles,
mammals and reptilelike ancestors, and
whales and terrestrial
ancestors.
Comparative anatomy
•  The comparison of body structures in
different species.
•  Anatomical similarities give signs of
common descent.
Homologous structures
•  Different functions but
similar structure due to
common ancestry
•  The bat's wing, whale's
flipper, monkey's arm and cat's foreleg are
homologous structures.
http://evolution.berkeley.edu/evolibrary/home.php
•  Share the same basic
skeletal structure, location
and pattern of
development that was
present in their common
proto-reptilian ancestor.
Vestigial structures •  Vestigial structures are
leftover, homologous,
evolutionary, "baggage" with
little or no current function.
•  Whales and some large
snakes have internal remnants
of hind leg bones that reflect
their evolution from fourlegged ancestors.
Analogous structures
•  Similar in
function only,
not evolutionary
relationship
•  Ex. Bird wings
and insect wings
Biogeography
•  Explained by understanding plate tectonics and
dispersal of species.
•  The study of organisms, past and present, and of
related patterns of variation over the earth in the
numbers and types of living things.
Dispersal of species
•  Organisms will move
from their birthplace to a
new site.
•  This movements allows
for new organisms to
reach new environments,
increase genetic variation
within populations and
evolve.
•  There are barriers to
dispersal.
Molecular Biology
•  Use of DNA
sequences, amino
acids and proteins to
determine relatedness
of different organisms.
•  Can be used as a
TEST to compare
relationships.
•  Based mostly on DNA
sequencing.
Comparative Embryology
•  Similar stages and structures in the early
development of different animals suggest
that they arose from a common ancestor that
also had those structures. Organizing the evidence
•  Systematics and Taxonomy
•  Systematics is the study of life's diversity and
organization. It includes taxonomy which involves
describing and naming new taxa, arranging them into a
convenient, formal classification scheme, and providing
means of identifying them
•  All classification schemes are hypotheses that reflect our
current understanding of the relationships among
organisms.
•  A phylogeny is a classification
that reflects a group's
evolutionary history. Such
relationships, and the
classifications that reflect
them, must be based on
homologous characters,
characteristics that point to
common ancestry. •  A cladogram is a branching
diagram that links the
descendants of common
ancestors.