Download Theory supported by evidence Biological

Evolution
To see where we might be going, we must
understand where we have been
Robert Tamarkin, 1993
Definition?
•Theory supported by evidence
•Biological evolution concerns changes in
living things during the history of life on
earth.
•Sharing of common ancestors
•Darwin term: descent with modification
Formation of the Earth
• 4.6 billion years old
• Universe 13.7 billion years old
• Complex: but woven out of 30ish main molecules
– oxygen, hydrogen, carbon, nitrogen, Sulphur
and phosphorus. (evidence #1)- present in early
Earth- amino acids, RNA, DNA, Phosphorus
(ATP????)
• Collision Theory and gravity.
Evidence of Evolution
Earth is Old
•Fossils: the remains or impression of a prehistoric
organism preserved in petrified form or as a mold
or cast in rock.
–record shows changes in organism over the past
3.6 billion years.
–Transitional species – show the link between an
ancestral form and that of the descendants (many
examples)
Changes begin
from simple to
more complex
Generally
older
fossils
are lower
in the
strata
First Life Form
– simple cells –
fossil evidence
3.4 billion years
ago
Fossil Record Supports Evolution
• Millions of fossils have been discovered
• Fossil record shows changes of organisms through time
• Early earth shows simple life forms. As time passes life-forms become more
complex
• Documents the order of appearance of groups and types of organisms
• The discovery of thousands of transtitionals species show transtions from fish to
tetrapods (fish to salamanders, salamanders to reptiles), dinosaurs to birds,
proto-horses to hores , apes to human, synapsid to mammals.
• Document major crises in Earth’s history and the recovery from events.
Example of transitional species- Whales
Meet the transitional
species
Horse Evolution -
Transitions- changes from 4 toes to 1 toe
Changes in skull size and changes in height
From Land to Water
One intermediate fossil between fish and the first
animals
Tiktaalik
375 million years
ago
Oxygen Environment
•What type of organisms increased in
numbers to pump oxygen into the air?
Photosynthetic
Red beds
Luckily- happened slowly 2.7 to 2.0
Descent with Modification
• A shared character is one that two lineages have in
common, and a derived character
is one that is in the lineage
leading up to a clade (group)
and sets members of
that clade apart from
other individuals.
• Amniotic egg, lungs, vertebral
Columns, etc.
Radiometric Dating
Radiometric Dating
*Fossils
strata
show relative dating by comparing data in the rock
*Radiometric Dating ability to use absolute dating - done by
comparing proportions of radioactive isotopes in the sample.
* Radiometric Elements are unstable (called parents) and they
decay into different elements (daughter elements). Uranium to
lead.
http://science.howstuffworks.com/29145-100-greatest-discoveries-radiometric-datingvideo.htm
•Earth’s oldest crustal
rocks – 4.03 billion years
old.
•Oldest metamophised
sediment – zircon crystals
found in Canada- 4.4
billion years old.
Radiometric Dating Supports Evolution
• many naturally-occurring elements are radioactive and they break down, or decay, at known
predictable rates.
• Many isotope pairs are useful in dating the Earth such as rubidium/strontium, thorium/lead,
potassium/argon, argon/argon, or uranium/lead, all of which have very long half-lives, ranging
from 0.7 to 48.6 billion years.
• Subtle differences in the relative proportions of the two isotopes can give good dates for rocks of
any age.
• Geologists have made many radiometric age determinations, and continue to refine earlier
estimates with new data. Dates are often cross-tested using different isotope pairs.
• Results from different techniques, often measured in rival labs, continually confirm each other.
• Repeatable results
• Comparisons to other methods of absolute dating.
Charles Darwin
• Not exactly a star student, but he revolutionized the scientific view of the natural
world with his Theory of Natural Selection
• Traveled on the Beagle where his journey began in 1831 for a 5 year voyage
• The Beagle traveled from Europe to the Galapagos Islands then to Australia
around the Cape of Good Hope and back to Europe
Observations aboard the Beagle
1.
Species vary globally
a. Two similar species live in different areas of the world
2.
Species vary locally
a. Differences among tortoises in the Galapagos islands
3.
Species vary overtime
a. Fossils of extinct animals looked similar to living animals
Putting the pieces together !
• Some of the species Darwin noted
had never been identified before
• There were similarities between the
finches on the Islands when
compared to the ones in South
America.
• What could it be????
Natural Selection
• Natural Selection: Organisms best
suited to their environment survive
and are able to produce offspring
• Fitness-How well an organism can
survive
• Adaptation- Any heritable
characteristic that increases an
organisms ability to survive
Conditions Necessary for Natural
Selection
• Variation among offspring (must be genetic)
• More organisms born than can survive (surplus) –
creates competition for limited resources…Struggle
for existence
• Individuals with the adaptations with the highest
fitness for the environment live and pass along
their traits.
Artificial Selection
• Artificial selection is when nature provides the variation amongst a species and
human select the traits that they find most useful.
Comparing anatomy
• Homologous Structure: structures that are shared by related species and that
have been inherited from a common ancestor
• Analogous Structures: When the structure is common but the function is different
and example of this is the wing of a bird and a horses hoof
Comparing Anatomy
• Vestigial structures: inherited from ancestors but have lost much or all of their
original function due to different selection pressures acting on the descendent