1. Unit 5 - Evolution
Chapters 16 and 17

2. Evolution What is it? Change over a period of time
In biology, it is a change in the inherited characteristics of a population from one generation to the next.
Scientific theory that has been tested and supported over time, which keeps developing and expanding

3. Charles Darwin
Naturalist that sailed for 5 years on a ship called the Beagle.
Collected natural objects from each place he visited and documented his observations.

4. Galapagos Islands
Data collected from this group of islands found in the Pacific Ocean provided Darwin with many interesting observations.
Galapagos Islands have high biodiversity

5. Biodiversity
The variety of organisms, the genetic information they contain, and the biological communities in which they live.
Ecosystem Diversity: The number and variety of biological communities in which organisms live.
Species Diversity: The number and variety of species on Earth.
Genetic Diversity: The different forms of genetic info carried by all organisms living on earth today.
Gives rise to inheritable variation, the raw materials for evolution.

6. Darwin’s Observations
Darwin found a great variety of fossils.
Noticed similarities between living creatures and fossils of extinct organisms
Where did the new organisms come from and where did the old ones go?
Found diversity of living creatures.
Many of these creatures he observed were very similar to each other and to species on other continents
How did this diversity come to be?

7. Darwin’s Observations
He noticed how well an organism coped with its surroundings.
Fitness: ability of an individual to survive and reproduce, thereby passing on copies of its genes to offspring.
How organisms vary to be better suited for their environment.
Adaptation: Inherited physical and behavioral traits that improve an organism’s fitness in a given environment.

8. Darwin’s Observations
He began to wonder if the now separate species had once been the same species, but had somehow evolved differently when isolated from one another.

9. Darwin’s Observations
Spent 21 years studying other sciences, his observations and data and eventually formed a key idea that he presented in a book.
The Origin of Species by Natural Selection

10. The Origin of Species by natural selection
Provided evidence in support of the idea that life has changed, or evolved, over time.
Gave an explanation of why and how evolution occurs.
Introduced the concept of natural selection as a cause and explanation of evolution.

11. Natural Selection
Every organism is capable of producing more offspring than can possibly survive.
Variation among these offspring exists allowing them to adapt differently to their surroundings.

12. Natural Selection
A better adapted organism is more likely to survive to reproduce and pass on its genetic information.
These adaptations that improve survival and reproduction are more common in a population’s gene pool over time.
Gene pool: The group of alleles that is shared by members of the same species.

13. Nature selects the most fit (well adapted) individuals to survive.
The result of natural selection is evolutionary adaptation
Figure 13.2
(a) A flower mantid in Malaysia
(b) A Trinidad tree mantid that mimics dead leaves
(c) A leaf mantid in Costa Rica

14. Natural selection…. Resistance to antibacterial soap
Generation 1: not resistant
resistant

15. ….In action Resistance to antibacterial soap
Generation 1: not resistant
resistant

16. Natural selection…. Resistance to antibacterial soap mutation!
Generation 1: not resistant
resistant
Generation 2: not resistant
resistant
mutation!

17. ….In action Resistance to antibacterial soap
Generation 1: not resistant
resistant
Generation 2: not resistant
resistant
Generation 3: not resistant
resistant

18. This is also how antibiotic resistant strains of bacteria develop!
Natural selection
Resistance to antibacterial soap
Generation 1: not resistant
resistant
Generation 2: not resistant
resistant
Generation 3: not resistant
resistant
Generation 4: not resistant
resistant
This is also how antibiotic resistant strains of bacteria develop!

19. Common Descent (a.k.a. Evolutionary Theory)
Darwin’s book also provided evidence that modern day organisms are the result of the slow process of evolutionary change and descend from a common ancestor.

20. Supporting evidence
Darwin used evidence from multiple fields of science to support his theory of evolution.
Developmental Biology (Embryology)
Anatomy
DNA/Biochemistry
Geology

21. embryology
Similar stages of embryo development occur in different organisms.
Organisms with similar developmental stages are considered to be closely related from an evolutionary standpoint.

22. anatomy Comparing body structure between different species
Presence of homologous structures
Similar structures in different organisms that developed from similar tissues in early development.
Example: All vertebrate forelimbs contain same set of bones

23. Homologous Structures

24. anatomy Presence of vestigial structures
Anatomical structures that are fully developed and functional in one group of organisms but serve little/no purpose in similar groups
Example: Human tailbone

25. DNA evidence DNA All organisms have the same DNA nucleotides
Same 20 amino acids
Evolutionary relationships can be determined by comparing genes and proteins of different organisms

26. DNA evidence
Similar DNA sequences in different organisms point to close relation.
Changes in anatomy were a result of changes in the genes that determine these characteristics.
Mutations: Change in genetic sequence that can sometimes change the characteristics of a organism.

27. Some mutations change organism's characteristics.
Mutations occur
Some mutations change organism's characteristics.
Bad
Characteristic
Good
Characteristic
Individual does
not reproduce
Individual
Reproduces
Trait becomes
less common
Trait becomes
more common

28. Similar proteins are produced in different organisms
Example: hemoglobin

29. geology
Darwin suggested that whales might have evolved from a mammal that lived on land based on fossil records.
Fossils have been found of many organisms that do not exist today.

30. GEOLOGY
Many current organisms are similar to very old fossils and fossil links often exist between them.
Conditions that create fossils are rare, so there will never be fossils of all the species that lived, creating a gap in this evidence that may never be closed.

31. Scales of evolution Microevolution Macroevolution
Evolution resulting from changes in the genes of a population.
Macroevolution
Evolution resulting from the appearance of new species.

32. microevolution
Evolution resulting from changes in the genes of populations
Can be seen over short periods of time
Examples: antibiotic resistant bacteria
How do these changes occur?

33. Forces of genetic change
Natural Selection
Can lead to an increase or decrease in certain alleles in a population
Gene Flow
The movement of genes into or out of a population.
Influenced by migration.

34. Forces of genetic change
Mutations
Can change the number and type of alleles from one generation to the next
Genetic Drift
The random change in allele frequency of a gene pool
Can lead to a population that differs genetically and physically from the original.

35. Forces of genetic change
Mate Choice
In sexually reproducing populations, preferences of mate choice influence the alleles present.
All of these forces of genetic change can produce major evolutionary changes if given enough time.
Enough time = millions / billions of years

36. macroevolution Speciation Species The formation of new species.
A population must evolve enough genetic changes so that breeding cannot occur between the emerging, genetically different groups.
Species
A group of similar looking organisms that can breed with one another and produce fertile offspring.

37. Cladogram A diagram that depicts the origin of new species.

38. Causes of Speciation
Reproductive isolation occurs when two populations can no longer breed to produce future offspring.
Groups may diverge over time
One ways this isolation can occur
Change in geography

39. Geographic isolation
A physical barrier divides a population preventing interbreeding.
Over time, the populations diverge by adapting to their different environments and natural selection.
Example: Death Valley, CA has isolated ponds formed by springs. Each pond has a different species of fish that live in it. Geologic evidence shows that Death Valley was once covered by a huge lake.

40. extinction Occurs when a species fails to produce any more offspring.
99% of the Earth’s species have become extinct.
Is as much a part of evolution as speciation.
Many cases of extinction are the result of environmental change.
Species that were once well adapted to an environment may become poorly adapted if the environment changes rapidly enough