Transcript IB Student Evolution PP

Maddie Fox
EVOLUTION
Charles Darwin
• 1809- Born in England
• 1830- Received his B.A. from Cambridge
• 1832-1836- Darwin serves as ship naturalist on
the HMS Beagle
• 1844- Wrote essay on the origin of species and
natural selection, but was reluctant to publish,
wanted more evidence
• 1858- Read Alfred Russel Wallace’s manuscript
containing a theory on natural selection
• 1859-Published On the Origin of Species by
Means of Natural Selection
The Origin of Species
1. Today’s organisms descended from ancestral
species that were different from modern
species.
2. Natural selection provided a mechanism for this
evolutionary change


The basic idea of natural selection is that a population can
change over time if individuals that posses certain heritable
traits leave more offspring than other individuals.
Natural selection results in evolutionary adaption, an
accumulation of inherited characteristics that increase the
ability of an organism to survive and reproduce in its
environment.
Jean-Baptiste de Lamark
Two Main Concepts
 Use and Disuse: Idea that body parts that are
used extensively become longer and
stronger, while those that are not used
deteriorate.
 Inheritance of Acquired Characteristics:
Modifications that are acquired during the life
of an organism could be passed on to
offspring.
Origin of Life: Problems
For spontaneous origin of life on earth to occur,
four specific processes would have been
needed.
1. Synthesis of organic molecules
2. Synthesis of polymers from organic molecules
3. Mechanisms for the self-replication of organic
molecules
4. Packaging of these molecules inside of
membranes.
Origin of Life: Solutions
Organic compounds could have been formed or
delivered from:
 Space, delivered by comets
 Intertidal zones
 Near volcanoes
 Deep-sea hydrothermal vents
Speciation
Speciation is the formation of a new species
and is initiated when a single gene pool is
separated by various kinds of barriers. Barriers
could include:
 Geographic isolation
 Hybrid infertility
 Temporal isolation
 Behavioral isolation
Terms of Speciation
 Allopatric speciation: Geographic separation
 Sympatric speciation: Same geographic area
 Adaptive radiation: Development of many
species from a common ancestor
 Divergent evolution: Species evolve to
become increasingly dissimilar
 Convergent evolution: Species evolve to
become more alike
Half-Life
Radioisotopes are often
used to identify the age
of rocks and fossils.
Half-life is the time it
takes for half of a
radioactive isotope to
decay. An object that
contains a radioactive
isotope will give off half
of its radioactivity after
one half life had passed.
# of half-lives
elapsed
Fractions
remaining
Percentage
remaining
0
1/1
100
1
1/2
50
2
1/4
25
3
1/8
12.5
4
1/16
6.25
5
1/32
3.125
n
1/2ⁿ
100(1/2ⁿ)