Download Natural Selection PP Notes

Name ___________________________________
Period _____
Assignment: Natural Selection PowerPoint Notes (#
, 10 pts)
Jean-Baptiste Lamarck (1744-1829)
1. “_______________________” - Individuals lose characteristics they do not require and
develop those which are useful.
2. Inheritance of acquired traits - Individuals inherit the acquired traits of their ancestors.
Jean-Baptiste’s theory was later ______________________!
Charles Darwin
 Set sail on the ______________________ in 1831
 Became the ship’s naturalist
 Arrived in the Galapagos Islands in 1835
 Observed that the animals on the islands were similar to those on the mainland
 Most obvious difference were the sizes and shapes of the finches’ (small birds) beaks
 ________and __________ of the beaks were adapted to what the birds ate
 Wrote: _____________________________________
EVOLUTION
Definition: The _______________________ in a species over time.
NATURAL SELECTION: Organisms that are better ______________to an environment are
more likely to _______________and _________________ than organisms that are less well
adapted.
→
→
In your own words, describe what is happening in the pictures above, why is there a benefit to
being the tan bug?
FACTORS THAT AFFECT NATURAL SELECTION:
1. _____________________: most species produce far more offspring than will/can survive
2. Competition: since food and resources are limited, the offspring have to compete to survive
Darwin called it: “_______________________________”
3. Variation: Members within a species exhibit ____________________ – these differences must
be inheritable
4. Survival to reproduce: Only those individuals that are better suited to the environment will
survive and reproduce (“_________________________”).
HOW DO NEW SPECIES FORM?
 Natural Selection
 _________________________: Fossil records show that when the continents were
connected animals walked across. When the continents separated, the animals were
separated.
 ___________________________: Originally, the pepper moth was white, which was
good because it could blend in. Then,
trains were invented and the soot they
produced covered the trees. Making the
trees black. The moths that were black
could now survive better.
 __________________: Some species
are more susceptible to mutations.
Some mutations allow the animal to
survive; other mutations do not allow the animal to survive. The
mutations that are not decrease the chance of survival remain.
 Man

____________________: Example: Dogs
→
EVIDENCE OF EVOLUTION
Fossil Record
How fossils form:
 An organism dies and becomes buried in ________________________
 Minerals gradually replace the bones and more sediments cover the fossil
Similarities in Body Structure
 If the two organisms have body
structures that are similar, they may
have had a _______________
_________________.
Similarities in Early Development
 Scientists look at ______________
of different organisms and find that
many embryos resemble one
another.
_________________________________
 A structure found in an organism that is no longer
in use but may have been useful at some point in
the organism's life.
Similarities in _______
 The more similar the sequences of DNA are, the more closely related the organisms are.
 Humans and chimpanzees DNA is more similar than human DNA is to dog DNA.
PATTERNS OF EVOLUTION
Divergent Evolution
 New species develop traits that differentiate them from their ancestors
 Divergence accounts for descendants that differ from their ancestors and from one
another
Convergent Evolution
 Unrelated animals develop similar body forms to fill same niche
________________________
__________________________
(label convergent or divergent)
Adaptive radiation
 __________________ filled ecological niches vacated by dinosaurs
 Greatest mass extinction occurred millions of years before us- the dinosaurs
 More than 90% of all species died out – the animals that remained filled the gap
HOW WE KNOW WHAT HAPPENED WHEN
______________dating
 Rocks that fossils are found near contain radioactive elements.
 The half-life of a radioactive element is the time it takes for
half the atoms in an element to change into a stable element
(carbon 14 into carbon 12)
Stratigraphy
 Fossils from organisms that died ______________ are buried
________________ in the sediment/rock than fossils from
organisms that died more recently.
Molecular clocks
 When a stretch of DNA does indeed behave like a molecular
clock, it becomes a powerful tool for estimating the dates of
lineage-splitting events.