1. Evolution Evolution and Diversity The Age of the Earth
The Fossil Record
Evidence from Living Organisms
How Change Occurs

2. Developing a Theory of Evolution
Jean Baptiste Lamarck proposed a theory of evolution and adaptation
He stated that organisms respond to the environment by acquiring new traits and then passing them to subsequent generations (3 ways)
Desire to Change – organisms change because they want and need to survive
Use and Disuse – Size of organs decrease with less use and increase with more use
Passing traits – desirable traits are passed on to offspring

3. According to Lamark…
A giraffe would have stretched its neck to reach the leaves in a tree…
…or if you cut off your finger your kids would be born without a finger.

4. Evolution and Diversity
The Theory of Evolution is a proposed set of mechanisms that lead to changes in species over time
Charles Darwin proposed the most accepted version of this theory after he wrote chronicles aboard the HMS Beagle
He noted that earth contains a large, diverse number of different organisms in which to study
Darwin proposed that each organism has its own behavior and phenotype to help it survive environmental conditions
He called this “fitness” which is the major theme of natural selection (survival of the fittest)

5. Charles Darwin

8. Natural Selection Natural Selection-
1. Process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do
It is also a theory to explain the mechanism for evolution.

9. 2. Genetic Variation- within a population, individuals have different traits; occasionally new traits may appear in a population due to mutations, crossing over, random fertilization, independent assortment.
3. Struggle to Survive- individuals must compete with each other in a “struggle for existence”. Some traits improve and individual’s chance to survive while other traits reduce this chance.
A trait that makes an individual successful in its environment is called an Adaptation.

10. 4. Differential Reproduction- organisms with the best adaptations are most likely to survive and reproduce and through inheritance, the adaptations will become more frequent in the population.
Populations may begin to differ as they become adapted to different environments, even if they descend from the same ancestors.

12. What is Fitness?

13. Natural Selection
The theory of Natural Selection proposes that nature changes species by selecting traits
Darwin sometimes used the phrase
“Survival of the Fittest” to explain Natural Selection.
In evolutionary terms, Fitness is a measure of an individual’s hereditary contribution to the next generation.
The behaviors and characteristics that help an organism survive in its habitat and successfully reproduce.

14. Fitness examples:
camouflage
&
mimicry

15. Camouflage

16. The Age of the Earth Evidence lies in stone
James Hutton (1788) proposed that rain, wind, temperature, and natural disasters shaped the valleys, mountains, and rocks over extremely long periods of time
Charles Lyell (1830)contributed to this by adding that current observations of volcanic eruptions and other natural disasters shows that Hutton was correct in assuming the Earth was older than originally predicted

17. humans evolve First placental mammals Flowering plants dominant
First birds
1st dinosaurs
First reptiles
First seed plants
First amphibians
First vertebrates
First invertebrates
eukaryotes
prokaryotes
Life evolves

18. Rocks; The Earth’s Clocks
The geologic time scale provides a measurement tool for determining the relative age of the earth
Due to patterns in the rocks, it was determined that layers on top are younger than deeper layers
It followed that fossils that are found in layers tend to be older the deeper you dig (relative dating)
Radioactive dating
The rate of radioactive decay of elements provides an accurate measurement of age (half-life)
The length of time required for half of the radioactive atoms in the sample to decay

19. Strata or Rock Layers The layers on the top are younger than the layers on the bottom.

20. Plate tectonics
245 million years ago, continents were joined together in a land mass called Pangea. Fossil evidence shows this.

22. The Fossil Record Most fossils are found in sedimentary rock
Rock created by sand and silt
Some organisms die where sediment doesn’t collect quickly enough to preserve an organism or its remains. That is why there are holes in the fossil record
By studying fossils of the same species of organism from different eras, we can gain visual evidence of the change over time
Paleontologists study fossils to create the fossil record

26. Evidence from Living Organisms
Embryology – the study of developing embryos
Many similarities can be studied between embryos of different species
This leads us to believe that a similar development has come from a common ancestor

27. Embryology
Study of embryos and the relationships that exist between different species

29. Homologous – Analogous – Vestigial Structures
Homologous structures – structures are similar between organisms even if they have a different function.
Whale flipper and a human arm
Analogous structures – two organisms that share a common function, but have different structures to achieve the result
Bird wing and a butterfly wing
Vestigial structures – structures an organism possesses, but no longer has a use for
Human appendix, wisdom teeth, etc

30. Homologous Structures
Structure is similar even if function is different

31. Analogous Structures
Functions are the same between species; structures are different

32. Vestigial Structures
Evidence shows the organ was once used, but not any longer

33. How change occurs

34. Artificial Selection
Breeders and farmers use artificial selection to produce desirable/marketable offspring
This is called artificial selection
It is opposite of natural selection in the sense that it is not necessarily the survival of the fittest

36. Malthus and Lyell
Thomas Malthus observed that humans were being born at a faster rate than they were dying
War, famine, and disease control populations
These observations provided enough curiosity for Darwin to delve deep into his theory of Natural Selection
Charles Lyell showed evidence that the earth was old and had undergone many drastic changes
Darwin conjectured the idea that these drastic changes favored the strong and weaned out the weaker individuals
This was the groundwork for developing “Natural Selection”

37. Types of Evolution

38. Types of Evolution
Speciation – species become separated by one of several ways and change over time from the original parents to fit the new niche
Adaptive Radiation – One species can give rise to many different species (Darwin’s Finches)
This is a form of divergent evolution
Convergent Evolution – A form of evolution in which two species resemble each other after years of change
Genetic Drift – Random change in the frequency of genes in a population

39. Speciation
The formation of a new species

40. Adaptive Radiation
One main species can give rise to several new species after being geographically separated

41. Convergent Evolution
The separate evolution of two species that results in both species developing similar characteristics

42. Genetic drift
The random change of allelic frequency in a population

43. Punctuated Equilibrium vs. Gradualism
Evolution occurs much more slowly (gradually) and consistently
Speciation occurs at intervals further apart
Punctuated Equilibrium
Evolution that occurs at more intervals and less consistently
Speciation occurs more frequently

45. Summary Evolution is a mechanism of change
It can occur gradually or in spurts
Charles Darwin provided a mechanism for this change (Natural Selection)
Evolution occurs within populations
Convergently – different species develop similar characteristics
Divergently – same species develop differently from each other due to environmental
Fossil evidence shows support for speciation
Many species have shown differences over time
Different methods have been used to determine the age of the earth