IB Biology 5.1 Evidence for Evolution

1. 5.1: EVIDENCE FOR
EVOLUTION

2. Understandings
• Evolution occurs when heritable
characteristics of a species change.
• The fossil record provides evidence for
evolution.
• Selective breeding of domesticated animals
shows that artificial selection can cause
evolution.
• Evolution of homologous structures by
adaptive radiation explains similarities in
structure when there are differences in
function.
• Populations of a species can gradually
diverge into separate species by evolution.
• Continuous variation across the geographical
range of related populations matches the
concept of gradual divergence.
Applications and
Skills
• A: Development of
melanistic insects in
polluted areas.
• A: Comparison of the
pentadactyl limb of
mammal, birds,
amphibians, and reptiles
with different methods of
locomotion.

4. Charles Darwin
1809 - 1882
“……can we doubt (remembering that many more individuals are born than can possibly survive)
that individuals having any advantage, however slight, over others, would have the best chance
of surviving and procreating their kind? On the other hand, we may feel sure that any
variation in the lease injurious would be rigidly destroyed. This preservation of favourable
variations and the rejection of injurious variations, I call NATURAL SELECTION.” – On the
Origin of Species

6. Half-life

7. • Radiocarbon dating measures the percentage of
𝟏𝟒
𝑪
(radioactive) in relation to the percentage of
𝟏𝟒
𝑵 (stable)
• Half life of
𝟏𝟒
𝑪 is 5,730 years (ratio of radioactive isotope
to stable isotope is 50/50)
• Only accurate up to about 50k years; eventually there
aren’t enough
𝟏𝟒
𝑪 atoms left to determine an accurate
age

9. Whale evolution: http://www.youtube.com/watch?v=I2C-3PjNGok

11. The Bizarre Truth About Pure Breeds
http://media.outsideonline.com/images/dog-breeds-now-and-then_fe.jpg

13. Go to pg 222

14. Characteristic Bat Bird Human Horse Dolphin Turtle
Number of Digits
Description of
phalanges
Type of
locomotion the
limb is adapted
for

15. Adaptive Radiation

16. Transient Polymorphism

18. TOK
• What are the arguments for and against the peppered
moth as an example of evolution?
• Should it continue to be used in classrooms as an
example?
• When there are disagreeing sides, which one should we
believe?
• What have you learned from TOK to help you make your
decision?