1. Evidence of Evolution (and Natural Selection)

2. Evidence supporting evolution
Fossil record
shows change over time
Geographic Distribution (past and present)
Anatomical record
comparing body structures
homology & vestigial structures
Molecular record
comparing protein & DNA sequences
Artificial selection
human caused evolution

3. 1. Fossil record Layers of rock contain fossils
new layers cover older ones
creates a record over time
Fossils show a series of organisms have lived on Earth
over a long period of time
Through time, these organisms evolve into new forms

4. Fossils shape ideas about evolution Fossils: direct or indirect remains of organisms preserved in media such as sedimentary rock, amber, ice, or tar
Fossilized organic matter in a leaf
Ammonite casts
Fossilized organic matter in a leaf
Ice Man”

5. Fossils tell a story…

6. What has the fossil record shown us?
The creatures alive today haven’t always been around.
But they do resemble creatures that were present in the past (See elephant evolution below)

7. Whale Evolution- Whales originated as predatory land mammals, that evolved into Ocean Mammals?
Complete series of transitional fossils
We found the fossil — no joke! ?
Where are the intermediate fossils? ? ?
There are innumerable intermediate & transitional forms
Whales as land creatures returning to the water….
Where are the intermediate forms of whale ancestors?
Cartoon making fun of this idea.
The cartoons disappeared years ago when this fossil was found.
Ambilocetic natans = “Walking whale who likes to swim”
4-5 intermediate forms all found in last 2 decades
Indus River valley in between India & Pakistan.
Ocean Mammal

8. Ambulocetus- whale ancestor
Carl Buell

9. Evolution from sea to land
2006 fossil discovery of early tetrapod
4 limbs
Missing link from sea to land animals

10. Evolution of Birds
Archaeopteryx, pictured along with other fossils that illustrate a link between birds and dinosaurs

11. Trilobytes… lots of diversity, resulting from heavy selective pressures and empty niches

13. Geographic Distribution
Different species descended with modification from a common ancestor- Populations in different places adapted to different environments…
Convergent evolution-Different species living in similar environments in different parts of the world sometimes have similar structures and functions because they experienced similar pressures of natural selection-

14. Convergent evolution 3 groups with wings
Flight evolved 3 separate times —
evolving similar solutions to similar “problems”
3 groups with wings
Does this mean they have a recent common ancestor?

15. 2. Anatomical record Animals with different structures on the surface
But when you look under the skin…
It tells an evolutionary story of common ancestors

16. Compare the bones The same bones under the skin
limbs that perform different functions are built from the same bones

17. Homologous structures
Homologous Structures- Structures that come from the same origin (same tissues during development)
homo- = same
-logous = information
Forelimbs of human, cats, whales, & bats
same structure
on the inside
same development in embryo
different functions
on the outside
evidence of common ancestor

18. Evolution of Land Vertebrates Note: homologous limb bones

19. Hind leg bones on whale fossils
Vestigial organs structure—a body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor.
Hind leg bones on whale fossils
Why would whales have pelvis & leg bones if they were always sea creatures?

20. Some Examples

21. Other Vestigial Organs?
Can you Provide examples of any other vestigial organs?
Appendix
Coccyx

22. But don’t be fooled by these…
Analogous structures-
Structures that look similar and have the same function
But: different internal structure & development
different origin
no evolutionary relationship
Solving a similar problem with a similar solution

23. Analogous structures Dolphins: aquatic mammal Fish: aquatic vertebrate
both adapted to life in the sea
not closely related

24. 3. Molecular record Comparing DNA & protein structure
everyone uses the same genetic code!
DNA 10 20 30 40 50 60 70 80 90
100
110
120
Lamprey
Frog
Bird
Dog
Macaque
Human 32 8 45 67
125
compare common genes
compare common proteins
number of amino acids different from human hemoglobin

25. Building “family” trees
Closely related species are branches on the tree — coming from a common ancestor

26. 4. Artificial selection
How do we know natural selection can change a population?
we can recreate a similar process
“evolution by human selection”
“descendants” of wild mustard

27. Selective Breeding “descendants” of the wolf
Humans create the change over time
“descendants” of the wolf

28. Artificial Selection gone bad!
Unexpected consequences of artificial selection
Pesticide resistance
Antibiotic resistance

29. Insecticide resistance
Spray the field, but…
insecticide didn’t kill all individuals
Variation in response to the chemical
resistant survivors reproduce
resistance is heritable
insecticide becomes less & less effective
The evolution of resistance to insecticides in hundreds of insect species is a classic example of natural selection in action.
The results of application of new insecticide are typically encouraging, killing 99% of the insects.
However, the effectiveness of the insecticide becomes less effective in subsequent applications. The few survivors from the early applications of the insecticide are those insects with genes that enable them to resist the chemical attack. Only these resistant individuals reproduce, passing on their resistance to their offspring. In each generation the % of insecticide-resistant individuals increases.

30. Adaptations: Evidence for Evolution
an adaptation is any variation that aids an organism’s chances of survival in its environment.
According to Darwin’s theory, adaptations in species develop over many generations
Because organisms have adaptation to their specific environment, each organism has become specialized.

31. Structural adaptations arise over time
camouflage, an adaptation that enables species to blend with their surroundings.
Because well-camouflaged organisms are not easily found by predators, they survive to reproduce.

32. Structural adaptations arise over time
Mimicry is a structural adaptation that enables one species to resemble another species.
Predators may learn quickly to avoid any organism with their general appearance

33. Convergent evolution led to mimicry
Why do these pairs look so similar?
Monarch male
poisonous
Viceroy male
edible
Which is the moth vs. the bee?
Which is the fly vs. the bee?
fly
bee
moth
bee

34. Physiological adaptations can develop rapidly
In general, most structural adaptations develop over millions of years.
However, there are some adaptations that evolve much more rapidly.
The evolution of insecticide resistance is an example of natural selection in action

35. Adaptation vs Acclimation
Adaptations are inherited trait (genetic) that increases an organism’s chance of survival.
May be anatomical, physiological, or behavioral (instinctual) and will happen over many successive generations.
Ex. Deer growing thicker coats in the winter
An Acclimation is a short term learned response to an environmental change.
Ex. Deer avoiding daytime browsing during hunting season

36. Evolution and Adaptations
Galapagos tortoises have shell shapes that are adapted to the vegetation of their island.
Tortoises that live on islands that have low vegetation have domed shells so that they don’t get stuck.
Tortoises that live on islands with high vegetation have saddle shells so that they can stretch higher for out of reach foods.

38. Cladograms shows the evolutionary development of the species.
shows the relationships between species.
resembles a tree and its branches.

39. Example Cladogram

40. How to Interpret a Cladogram
To determine how closely related organisms are to one another :
look for vertices or nodes
they occur at (G), (F), and (E).
species that share the same node are more closely related to each other
(B) and (C) are the most closely related because they share the most recent
ancestor (E).
(A), (B), (E), and (C) are also closely related through (F).

41. How to Read a Cladogram
To determine approximate age
examine where in the cladogram the species is found.
the bottom of the cladogram is where the most ancient (oldest) species are Found.
as you go up the species get younger and younger.
oldest species = (G)
youngest = (A), (B), (C), and (D).
To determine the amount of evolution in a species
look for a species that has produced a number of new species from it.
species (F) has evolved to form 4 new species ; (A), (B), (C), and (E).
species (D) has remained in its own lineage for many millions of years.

42. Example Cladogram