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Evidence for Evolution
•Fossils
•Comparative Anatomy
•Vestigial organs
•Distribution of Plants and Animals
•Related Species
•Genetic code is universal
Fossils
• Allows us to infer lines of evolution
• Older fossils are in deeper strata
• Radioactive dating is used to determine the
age of fossils
– Radioisotope has it’s own unique rate of
decay
– Half-life = amount of time it takes for half of
the radioisotope to decay
Fossils Continued
• Bias in the fossil record – some organisms
less/more likely to fossilize
• Aquatic organisms become covered by
sediment, while terrestrial organisms often
decay quickly or destroyed by scavengers
• Shells and bones make the best fossils
Comparative Anatomy
• Forelimbs similar in
mammals, birds,
reptiles, amphibians,
and even fishes
• These are homologous
structures: features
with similar underlying
structure – descent
from a common
ancestor
• Analogous Structures: Similar in
function/appearance but not in origin or
development
• Arise from Convergent evolution
(evolution that is similar, but species do
not share common ancestor)
Vestigial Organs
• Remnants of organs that were
previously used but no longer are
Biogeography
• Def: The study of the distribution of plants and animals
• Evolution of each species occurs only once
• The place where the evolution of an organism occurred
is called center of origin
• Not a single point, but a range of the population
• Each species spreads out until stopped by a barrier
Similar Patterns of Development of
Species
• Evolution is
conservative: natural
selection builds upon
what the organism
already has
Genetic Code is Universal
• ALL organisms use the
same genetic code
• “UUU” codes for the
same amino acid in
every organism to
examined to date
(plants, insects,
bacteria, animals, etc)
Other Points of Evidence
• Organisms that are remotely related, such
as humans, oak trees, and E-Coli have
some of the same proteins (cytochrome c)
– There are differences in the amino acid
sequences for cytochrome c
– Organisms more closely related have less
differences
Other Points of Evidence Cont.
• Can use DNA sequencing (determining the
order of nucleotide bases in DNA)
• Greater similarities in nucleotide
sequences = closer relationship
See book pg. 315
Evolution in New Zealand
• No native terrestrial
mammals (have bats)
• No mammals to prey
on birds
• Many species of birds
that have filled the
niches of mammals
and remain
unprotected against
introduced mammals
Tree Fossils
Glacier
Moa
• Extinct giant flightless
bird of New Zealand
• 15 different species
• Hunted by humans
Takahe
• a large flightless rail, became the sheep of New
Zealand, browsing grasslands.
Weka
Kea
Bush Wrens
• Scurry about on the forest floor, mice-like,
in pursuit of insects.
Kokako
• weakly flighted wattlebirds, behave like
squirrels, hopping
through branches after
fruit.
Paradise Ducks
Kiwi
•
•
•
•
Blind and flightless
Nocturnal
Has Whiskers
Nostrils at end of
beak (used to find
food in the ground)
• Has bone marrow