1. Evidence for Evolution
Fossils
Structures – Homologous, Vestigial
Molecular Biology

2. Fossils
Can trace evolutionary history – see earlier forms of an organism

3. Fossils
Can locate when organisms lived (approx)

4. Homology or Analogy?
Front leg of dog Front flipper of whale

5. Similar structures indicate common ancestry, even though functions are different

6. Analogous structures have similar functions, but different structures – thus not closely related

7. Vestigial Structures

8. Lamark
1744
-1829
An organism can acquire and then pass on characteristics during its lifetime to its offspring.
Giraffe example – stretched their necks to reach food and were able to pass that on to offspring
Frog “grew webbed feet to swim better” and passed that on to offspring

9. Darwin 1809-1882 Medical School, seminary, naturalist
1831 Beagle Voyage – 5 years – Galapagos Isl.

10. Darwin
Darwin’s voyage solidified his ideas on how living things change over time
All species of life have descended from a common ancestor
1859 – On the Origin of Species

11. Galapagos Discoveries
Beak adaptions

12. For Evolution to Happen:
Overproduction – more individuals are produced than can survive – shad eggs that we saw Struggle – organisms compete for resources – water, food, light Variation – with a population, no two individuals are identical - vary in size, speed, color disease resistance Selection – some are better suited for their environment – “Selected For” and reproduce

13. Theory of Natural Selection
Those individuals which are best adapted to their environment, are more likely to survive long enough to reproduce – thus passing on the genes for those traits to their offspring

14. Assume 2 things
There are a variety of traits to begin with – if not, a species won’t evolve, and might go extinct
There are environmental pressure giving some of those traits an advantage, other a disadvantage – if not, a population stays the same( there’s no pressure to evolve)

15. Example of Natural selection
Peppered Moths