1. Darwin & Natural Selection

2. Charles Darwin Proposed a way how evolution works
How did creatures change over time?
by natural selection
Collected a lot of evidence to support his ideas
British naturalist
What did Darwin say?
What evidence supports Evolution by Natural Selection?
What impact did Evolution have on biology?

3. Voyage of the HMS Beagle
Invited to travel around the world
(22 years old!)
makes many observations of nature
main mission of the Beagle was to chart South American coastline
After graduation Darwin was recommended to be the conversation companion to Captain Robert FitzRoy, preparing the survey ship Beagle for a voyage around the world.
FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain.
Darwin noted that the plants and animals of South America were very distinct from those of Europe
Robert Fitzroy

4. Voyage of the HMS Beagle
Stopped in Galapagos Islands
500 miles off coast of Ecuador
The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled Darwin.
On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland.
It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified on the different islands

5. Galapagos
Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland.
800 km west of Ecuador

6. Darwin found…many unique species
Many of Darwin’s observations made him wonder… Why?
Darwin asked:
Why were these creatures found only on the Galapagos Islands?

7. Darwin found…clues in the fossils
present day Armadillos
Darwin found…clues in the fossils
Darwin found:
Evidence that creatures have changed over time
ancient Armadillo
Darwin asked:
Why should extinct armadillos & modern armadillos be found on same continent?

8. Darwin found: Different shells on tortoises on different islands
Darwin asked:
Is there a relationship between the environment & what an animal looks like?

9. Earlier ideas on Evolution
LaMarck
evolution by acquired traits
creatures developed traits during their lifetime
give those traits to their offspring
example
in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring
not accepted as valid

10. Darwin’s view of Evolution
giraffes that already have long necks survive better
leave more offspring who inherit their long necks
variation
selection & survival
reproduction & inheritance of more fit traits 

11. natural selection explains the mechanism of evolution
Organisms that are best adapted to an environment survive and reproduce more than others
(1) Population with varied inherited traits
(2) Elimination of individuals with certain traits
(3) Reproduction of survivors

18. Then he waited 20 years
He checked his ideas but was afraid to upset people…….
Mostly he did not want to upset his wife

19. Bombshell A letter from Alfred Wallace
Wallace also had the idea of natural selection.
If you were Darwin, what would you have done after receiving Wallace’s letter?

20. We will publish together
Charles Darwin
Alfred Wallace
We will publish together
Thanks you’re a gent

21. But he had lots of evidence for the critics
Darwin got some very bad press
But he had lots of evidence for the critics
Figure 13.1x3

22. Evidence for evolution
Comparative anatomy
Human
Cat
Whale
Bat

23. Body Structures the same
Similar anatomy in different types of animals because of common ancestor

25. The Fossil Record
Fossils: a record of the history of life on Earth

26. Vestigial Organs
Vestigial Organs: “leftover” traces of evolution that serve no purpose –hips in whales

28. Embryology
embryos of all vertebrates are very similar early on

30. New evidence-Biochemical
Biochemistry: DNA with more similar sequences suggest species are more closely related
EX: Humans and chimpanzees share more than 98% of identical DNA sequences

31. Molecular biology - protein “clocks”
Human
Rhesus monkey
Mouse
Chicken
Frog
Lamprey
Last common ancestor lived 26 million years ago (MYA), based on fossil evidence
80 MYA
275 MYA
330 MYA
450 MYA

33. Darwin’s Finches – How and why did they evolve

34. Darwin’s finches Darwin’s conclusions variations in beaks
differences in beaks in the original flock
natural selection for most fit
over many generations, the finches with best beaks for local food had most chicks
offspring inherit successful traits
separate into different species

35. From 1 species to 14 species…
Warbler finch
Woodpecker finch
Small insectivorous
tree finch
Large
insectivorous
Vegetarian
Cactus finch
Sharp-beaked finch
Small ground
finch
Medium
ground finch
Large ground
Insect eaters
Bud eater
Seed eaters
Cactus
eater
Warbler
Tree finches
Ground finches
natural selection for best survival & reproduction
variation

36. Peppered Moth A
Which moth will the bird catch? B

37. Archaeopteryx
Missing link between reptiles and birds