1. Evolution Day 1
Journal Prompt: Tell me what you know about evolution, use the information you have heard in the past to give me a brief summary of what you think evolution is.

2. Evolution

3. Evolution
Change in a population of organisms over time.

4. Cladograms – a diagram of evolutionary relationships

5. Cladogram Introduction
Mr. Anderson’s introduction of Cladograms

6. Make a cladogram using what?
Derived Characteristics: unique characteristics of a particular group of organisms
AKA: found in one group of organisms but are not found in the older members of the lineage

7. Cladograms – a diagram of evolutionary relationships
Cladogram starts as a single branch that then splits several times into organisms who evolved from each other
If you follow a branch it sometimes splits at nodes into two or more branches to show new species
Used to tell how closely related organisms are

8. Cladograms
Each node represents a new trait that has evolved and the common ancestor that evolved that trait.
As you follow an organisms path in the cladogram from the beginning to the end, you can find out the organisms adaptations through time. Each node it goes through is a trait that it evolved, in that order.

9. Cladograms
100 million years go by …

10. Cladograms: Complete the table below!
Use the information in the table to construct a cladogram of these animals.
Organism
Derived characteristics
Backbone
Legs
Hair
Earthworm
Trout
Lizard
Human

11. Derived characteristics
Making a Cladogram
Which organism is least like the others?
Earthworm
Organism
Derived characteristics
Backbone
Legs
Hair
Earthworm
Trout
Lizard
Human
+ + +

12. Derived characteristics
Making a Cladogram
At the bottom help me to do the following:
Develop a cladogram showing the evolutionary relationships between all 4 animals.
Organism
Derived characteristics
Backbone
Legs
Hair
Earthworm
Trout
Lizard
Human
+ + +

13. Making a Cladogram
Earthworm
Trout
Lizard
Human
Hair
Legs
Backbone

14. Which animal is species X most closely related to on the cladogram?
Earthworm
Trout
Lizard
Human X
Backbone
Legs
Hair

15. Cladogram Activity Lets build a cladogram
Using the pictures of the organisms create a cladogram and answer the questions that follow the lab

16. Evolution Day 2
Journal: Explain what we use cladograms for. How do we make them?

17. Video Introduction What is evolution – Stated Clearly

18. Evolution
Change in a population of organisms over time.

19. WHAT IS EVOLUTION? To evolve: to change
A theory stating that all life has changed from simpler life to more complex life
Occurs over LONG periods of time
Evolution often supports that organisms have evolved from a common ancestor

20. But wait…… What did life start as to evolve??
Miller and Urey experiment: tried to replicate the origins of life on earth; mixed gases together to form complex molecules
Successful but experiment had several flaws so debate still ongoing as to the original life on earth

21. Theories of Evolution
Jean-Baptiste Lamarck – 1809 published his theory of evolution
Mechanism of Evolution = Inheritance of Acquired Characteristics

22. The theory of evolution
His explanations were:
Tendency towards perfection
Use and disuse= if you use it, you keep it; if you don’t use it, you lose it
Inheritance of acquired traits= traits are passed down through generations
Problem with his theory…he didn’t understand HOW

23. Theories of Evolution
Charles Darwin – 1859 published his theory of evolution in the major work, On the Origin of Species
Mechanism of Evolution = Natural Selection

24. Lamarck’s Ideas Organisms change over time
Organisms are adapted to their environment
All organisms are continually changing and acquiring features more suitable for their environment.

25. Legless lizard: Note ear hole.
Larmarck’s Ideas
Legless lizard: Note ear hole.
Snakes do not have ears.
During an organism's lifetime, there is selective use or disuse of its organs and traits. (Example: Lizard living in burrow…)
These acquired traits can then be passed on to their offspring. Over time, this process leads evolution of the species.

27. Comparison of Lamarck’s and Darwin’s Ideas on Evolution
Short necked herbivore lives in savanna
Grasses are available to the animals. Trees leaves are out of reach of most of them
Animals are adapted to their environment.
Darwin
Same

28. Comparison of Lamarck’s and Darwin’s Ideas on Evolution
The animals stretch their necks to reach the leaves on the trees. Continued stretching causes an elongation of necks.
The animals reproduce. The young have long necks.
Darwin
Due to variation in the population there is a range of neck lengths. Some animals naturally have longer necks than others.
Those with longer necks can reach the tree leaves.

29. Comparison of Lamarck’s and Darwin’s Ideas on Evolution
Lamarck In the event of a shortage of grasses (drought), the animals are able to feed on leaves.  The long necked animals are the most fit! These are the animals that survive and reproduce.
Darwin In the event of a shortage of grasses (drought), the animals are able to feed on leaves.  The long necked animals are the most fit! These are the animals that survive and reproduce.

30. Comparison of Lamarck’s and Darwin’s Ideas on Evolution
Over the next generations, the longer necked animals will continue to stretch and elongate their necks.
Each generation will pass on their longneck to their young
Darwin
Over the next generations, (due to mutations, new gene combinations, crossing over) there will again be variation in neck length
Those with the longest necks will be be most fit--with the greatest chance of survival.

31. Microevolution according to Darwin’s Ideas on Natural Selection

32. Macroevolution according to Darwin’s Ideas on Natural Selection
Speciation = formation of new species

33. Variation and Natural Selection
Most phenotypes (traits) are polygenic.
A graph of these traits often shows a bell curve.

34. Types of Natural Selection
Disruptive
Stabilizing
Directional

35. Stabilizing Selection
If individuals near the center of the bell curve have higher fitness (= leave a greater amount of fertile offspring) then stabilizing selection occurs.

36. Directional Selection
If individuals at one end of the bell curve have higher fitness then directional selection occurs.
Example: long necks

37. Disruptive Selection
If individuals at both ends of the curve have higher fitness than those in the middle then disruptive selection occurs.

38. Genetic Drift
If a small population is isolated from others of the same species, it is possible that just be “chance” one allele may become more common in a population.

39. I’ I’m an Eastern Gray Squirrel
Genetic Drift
I’ I’m an Eastern Gray Squirrel
For example: The Bronx, NY, becomes built up and trees are cut down. Few squirrels are able to survive. However, one section of the Bronx is set aside for the development of the Bronx Zoo. Trees are NOT cut down in this area. By chance, several of the gray squirrels in the area of the zoo have black fur (a variation in fur color). Over time, the allele for black fur becomes common in this population.

40. How do new species form? Example: Galapagos Finches
A small group of a species of finch arrives on one of the Galapagos Islands
These finches do not usually fly across open water—they may have gotten lost or were blown there by the wind.

41. Speciation continued!
Over time these original finches may have ended up on other of the Galapagos Islands through some chance occurrence.
USUALLY the finches do NOT fly from one island to another.

42. Speciation continued!
The Galapagos Islands had different environments.
Some had a low elevation and were dry with little plant material.

43. Speciation continued!
Others had a higher elevation with greater rainfall and many plants.

44. Speciation continued! Directional selection occurs:
One island may have seeds that are large and difficult to open.
Birds with a larger, thicker beak will have the highest survival rate on this island

45. Speciation continued! Directional selection occurs:
Another island may have seeds that are small and easy to open
Birds with a small, thinner beak will have the highest survival rate on this island

46. Speciation continued!
Reproductive Isolation: if the populations remain separate, and their gene pools continue to change, eventually they can no longer mate with each other—they are then TWO NEW SPECIES!!!
On the Galapagos Islands this processes resulted in the evolution of 13 different finch species.

47. Darwin’s Finches