1. Evolution

2. What is evolution?
Evolution is the process of biological change by which species of organisms change over time.
Evolution is a central theme in all fields of biology today.

3. Evolution is when organisms change over time
Evolution is when organisms change over time. So, modern organisms descended from ancient ones.

4. Evolution is a Theory – Just like Gravity!
Evolution is a well supported explanation of phenomena that have occurred in the natural world
A theory in science is a well tested hypothesis, not just a guess

5. Evolutionary Scientists
Charles Bonnet mid-1700s
First to use term evolution
Studied fossils
James Hutton
1795 Theory of Geological change
Jean-Baptiste Lamarck 1809
Charles Lyell
Geographical features can be built up or torn down
Charles Darwin
Thomas Malthus
Russell Wallace
Gave Darwin the drive to publish his findings

6. Malthus
Reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone

7. Jean-Baptiste Lamarck
He proposed the idea of inheritance of acquired characteristics:
changes in an environment caused an organism’s behavior to change
this would lead to greater use or disuse of a structure or organ.
the structure would become larger or smaller and would then be passed down to offspring
For example: giraffes’ long necks
Idea was WRONG!!

9. Charles Darwin
Natural selection was the theory he proposed to explain evolution.
He attempted to provide reasons for the biological diversity on Earth.
Developed his theory from personal observations and research of other scientists.

11. Charles Darwin (1809-1882) Sailed around the world 1831-1836 on the British ship H.M.S. Beagle.

12. What did Darwin’s Travels Reveal?
The diversity of living species was far greater than anyone had previously known!!
These observations led him to develop the theory of evolution!!
He observed the land and its inhabitants.
Finches and Tortoises

13. What did Darwin do?
He noticed the physical differences among island species.
Species on one island looked different from those on another island.
Island species looked different from those found on the mainland. This is known as variation.
Genetic variations arise from mutations
He noticed that the physical differences among the species were appropriate for their environment and diet.

14. Darwin finally published his ideas in 1859.
Other naturalists were developing the same theory that Darwin did.
Even though he was afraid of the Church’s reaction to his book he wanted to get credit for his work.

15. Natural Selection
The traits that help an organism survive in a particular environment are “selected” in natural selection

16. Evidence of Evolution Fossil Record Homologous Body structures
Similarities in Embryology
Biochemical Evidence

17. Evidence of Evolution: The Fossil Record
Fossil record provides evidence that living things have evolved
Fossils show the history of life on earth and how different groups of organisms have changed over time

18. Relative vs. Absolute Dating

19. Relative Dating Can determine a fossil’s relative age
Performed by estimating fossil age compared with that of other fossils
Drawbacks – provides no info about age in years

20. Absolute Dating Can determine the absolute age in numbers
Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain
Drawbacks - part of the fossil is destroyed during the test

21. Radiometric dating uses decay of unstable isotopes.
Isotopes are atoms of an element that differ in their number of neutrons.
A half-life is the amount of time it takes for half of the isotope to decay.

22. Primate Fossils
Australopithecus Homo erectus Homo sapien

23. Primate Bone Structure

24. Evidence of Evolution: Homologous Body Structures
Turtle
Structures that have different mature forms but develop from the same embryonic tissues
Ex: Wing of bat, human arm, leg of turtle
Alligator
Bird

25. Evidence of Evolution: Homologous Structures
Features that are similar in structure but appear in different organisms and have different functions.
Strong evidence for common ancestor.
Ex: forelimbs of humans, bats and moles.
Human hand
Bat wing
Mole foot

26. Analogous Structures Structures that perform a similar function.
Not evidence of common ancestry.

27. Vestigial Structures
Remnants of organs or structures that had a function in an early ancestor.
Ex: Ostrich wings, used for balance but not flight
Ex: Humans’ appendix

28. Evidence of Evolution: Similarities in Embryology
In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.

29. Embryological Development

30. Evidence of Evolution: Biochemical Similarities
Scientists study nucleotide sequences in DNA and proteins in different organisms to determine ancestry.
If the organisms are closely related they will have similar sequences of nucleotides in their DNA and arrangement of amino acids in proteins.

31. Evidence of Evolution: Biochemical Similarities
Organism
Amino Acid Differences
Human beta chain
Mouse 27
Gorilla 1
Kangaroo 38
Rhesus monkey 8
Chicken 45
Dog 15
Frog 67
Cow 25
Soy bean
124
The more similar the

34. Patterns, Processes, and Rates of Evolution

35. Adaptation
Darwin’ observations led him to realize that species must somehow be able to adapt to their surroundings.
Adaptations allow species to better survive in their surroundings.
Adaptations can lead to genetic change in a population over time.

36. Variation Among Species…
Organisms in the same species have different traits…
Known as variation
Variations may result from mutations or from how genetic material is rearranged during sexual reproduction
Variations within a species can have two results:
Speciation
Extinction

37. VariationSpeciation
Individuals with beneficial trait are well suited for the environment
They reproduce and pass the beneficial trait to their offspring
Individuals without the beneficial trait are less likely to survive and reproduce
Their traits are not passed.
Beneficial traits are passed while other traits disappear
These changes can eventually cause speciation

38. Speciation Evolution of a new species from an existing species
Occurs if the environment changes
Individuals with beneficial traits will survive and pass their traits on to offspring
Ex: Colder weather-animal with thicker fur
Ex: Type of food-animal equipped to eat new type
Ex: New predator-animal able to escape
Speciation Creates Biodiversity
Variety of organisms, their genetic information, and their habitats.

39. Mechanisms of Evolution
Genetic variation that leads to evolution can be a result of several things:
Mutations
Changes in DNA
Only mutations in gametes affect evolution
Gene flow
Introduction of genes from one population to another
Low gene flow=evolution of different species
Gene pool
Combination of genetic material from all members of a population
Affected by mobility-more mobility=higher rate of gene flow

40. Rates of Evolution Catastrophism-Georges Cuvier
He believed that a natural disaster would occur, cause landforms to change and cause species to become extinct
Once that species went extinct another would come in and take its place
Did not believe species changed over time

41. Rates of Evolution Gradualism-James Hutton Punctuated Equilibrium
Two main views:
Gradualism-James Hutton
Evolution occurs slowly and constantly over a long period of time
Darwin
Punctuated Equilibrium
Evolution occurs in spurts
Period of rapid speciation then long period of little to no change
Caused by random mutations or sudden changes in environment
Cambrian explosion

42. Rates of Evolution Uniformitarianism-Charles Lyell
Expansion of gradualism
Favored theory of geologic change
Proposed that changes occur slowly at a constant rate continuously

43. VariationExtinction
Permanent loss of a species.
Two causes:
Populations fail to adapt
Sudden, drastic changes in the environment
Humans attempt to prevent extinction of species through captive breeding, restricting hunting, and creating sanctuaries.

44. Mass Extinction
Extinction of huge numbers of species in a short period of time
Earth has experienced several mass extinctions
250 million yrs. ago-ocean invertebrates
65 million yrs. ago-dinosaurs