Transcript Ch. 15, Darwin`s Theory of Evolution

Ch. 17, The History of Life
• Paleontologists (pay-lee-un-TAHL-uh-jists) =
scientists who study fossils, history written into
stone
• The fossil record:
– Provides evidence about the history of life
on Earth
– Shows how species have changed over
time (evolved)
• 99% the species that have lived on Earth
are extinct!!!!
• Fossils form in sedimentary layers of rock
– Fossils at the top are younger than fossils
at the bottom, common sense,
or relative dating
Patterns of Evolution
•
•
Macroevolution = large-scale evolutionary patterns
occurring over long periods of time
Important topics in macroevolution:
1. Extinction = over 99% of all species that have
ever lived on earth are now dead, extinct.
2. Adaptive Radiation = a single species evolving
over time into diverse forms that live in different
ways
Phylogenetic Tree displays how the
process of change over time produces
today’s diversity in species
Present
Past
Present
Past
Which letter is closer related to group A?
Which letter is least related to group A?
Which letter groups did not make it to present day?
Present
A
B
C
E
D
Past
F
Macroevolution Cont.
3. Convergent Evolution = unrelated organisms come
to resemble one another
4. Co-evolution = process by which 2
species evolve in response to changes in
each other over time
-Predator- prey pressures, what food is
available, pollination, etc.
Macroevolution Cont.
5. Punctuated equilibrium = the pattern of long stable
periods of time interrupted by brief periods of more
rapid change
Yikes! I’m outta
here! He’s crazy!
Hee hee! I’m coming
to get you!
Reading Charts and Graphs
Which population would be more likely to experience an
extinction?
Mutations within
What is the ultimate source of variation?
Population A
the genetic
Mutations!!!!
code!!!
Population B