1. Chapter 14 (with some of ch.35 and 36)
Ecology and Evolution
Chapter 14
(with some of ch.35 and 36)

2. Charles Darwin His idea changed the way we look at the world.
His contribution was developing a scientific theory of biological evolution that explains how modern organisms evolved over time.

3. Remember What a “Theory” is
In science, the term theory is used to represent ideas and explanations that have been confirmed through tests and observations
The theory of evolution remains one of the most useful theories in biology because it explains many questions and observations

4. Some questions that can be answered by evolution.
Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale?
Why do organisms have structures they no longer use, like the appendix in a human? Non functioning wings in penguins
Why are there bones and fossil evidence of creatures that no longer exist? What happened to these creatures?
Why do so many organisms' morphology and anatomy follow the same plan?
Why is the sequence of DNA very similar in some groups of organisms but not in others?
Why do the embryos of animals look very similar at an early stage?

5. Darwin’s Theory of Evolution
The Theory of Evolution is considered a Unifying Theory of Biology, because it answers many of these questions and offers and explanation for the data.

6. Darwin’s Epic Journey
He was the naturalist aboard the HMS Beagle, a ship that traveled on a 5 year voyage beginning in 1831.
He collected samples and took notes in a journal.

7. Darwin’s Observations
He noticed three patterns of Biodiversity
Different, yet ecologically similar animals inhabited separate but ecologically similar habitats.
Example: different flightless birds live in similar grasslands across South America, Australia, and Africa.
Different, yet related animals occupied different habitats within a local area.
Same type of tortoise on different islands of the Galapagos.

8. 3. Some fossils of extinct animals were similar to living species.
Example: The extinct Glyptodont very similar to the armadillo

9. Ideas That Shaped Darwin’s Thinking
Darwin was not only influenced by his own notes, observations and animal specimens he collected, he was influenced by the work of other scientist.
Three works in particular, the work of:
Hutton and Lyell
Lamarck
Malthus

10. Hutton and Lyell
Concluded that the Earth is extremely old and that the process that changed the Earth in the past are the same processes that operate in the present.
Effect it had on Darwin's thinking: if the earth could slowly change over time, could life change too?

11. Lamarck’s evolutionary hypothesis
Lamarck suggested that organisms could change during their lifetimes by using or not using various parts of their bodies. He also suggested that these acquired traits could be passed on to their offspring.

12. Malthus
Malthus reasoned that if the human population grew unchecked, there wouldn’t be enough living space and food for everyone.
Effect it had on Darwin's thinking: if there was not enough food and space for organisms it would lead to a fight for survival. When Darwin realized that most organisms don’t survive and reproduce he wondered which individuals survive…and why.

13. Artificial Selection
One more thing that influenced Darwin’s thinking….artificial selection.
He studied change produced by plant and animal breeders.
Breeders knew that some plants produced larger fruits than others, some cows produce more milk than others. They chose those specific individuals to breed, thereby passing on the desired trait to the next generation.

14. 16.3 Darwin Presents His Case
In 1858, 20 years AFTER he developed his theory he published On the Origin of Species

15. Evolution by Natural Selection
His theory incorporates three main ideas:
Struggle for Existence
members of each species compete regularly for resources.
Variation and Adaptation
Some variation of traits are better suited to life in their environment that others.
Adaptation- characteristics that increases an organisms fitness
Survival of the Fittest
those organisms best suited to their environment will survive and reproduce.
Fitness- is measured by an organisms ability to survive and reproduce.

17. Evolution by Natural Selection
Natural Selection is the process by which organisms with variation most suited to their local environment survive and leave more offspring.
Natural Selection occurs only when:
More individuals are born than can survive (struggle for existence).
There is natural heritable variation (variation and adaptation)
There is variable fitness among individuals (survival of the fittest)

18. Evidence of Evolution Fossil Record Geographic Distribution
Homologous Body Structures
Embryonic Development
Molecular Divergence

19. Fossil Record Fossil- preserved remains of ancient organisms.
Many recently discovered fossils form series that trace the evolution of modern species from extinct ancestors

20. Geographic Distribution
Organisms may descend with modification from a common ancestor
Similar animals in different locations are products of different lines of evolutionary decent that have common environmental pressures

21. Homologous Structures
Homologous Structure- structures that have different mature forms but develop from the same embryonic tissue (similar structure/ different function)
Vestigial structure- structure/organ that is reduced in size an has no apparent function.

22. Embryonic Development
Many animals with backbones are very similar in the early stages of development.
Evidence that organisms have descended from a common ancestor.

23. The Evidence for Evolution
Traces of our evolutionary past are also evident at the molecular level
organisms that are more distantly related should have accumulated a greater number of evolutionary differences than two species that are more closely related
the same pattern of divergence can be seen at the protein level

24. Figure 17.7 Molecules reflect evolutionary divergence

25. Evolution of Populations

26. Charles Darwin Darwin’s Theory of Evolution
Organisms evolve by Natural Selection
Fitness- an organisms ability to survive and reproduce
Survival of the fittest- organisms that are better adapted to their environment will live long enough to reproduce
Darwin did not have an understanding of heredity (the passing of traits from parent to offspring)
Darwin was unable to explain:
the source of variation
how inheritable traits were passed from one generation to the next

27. Gene Pool
You can gain an understanding of evolution by studying individuals of a population.
Gene Pool- the combined genetic information of all the individuals in a population
Example: The gene pool of Taft includes all of the genetic information of all the people that make up Taft’s population

28. Allele Frequency
Allele Frequency- the number of times an allele occurs in a gene pool compared with the number of times other alleles occur.
Example- Green = GG, Purple = Gg & red = gg
The allele frequency for G is 87% (26 out of 30)
The allele frequency for g is 13% (4 out of 30)

29. Genetic Change Within Populations: The Hardy-Weinberg Rule
Variation within populations puzzled many scientists
why don’t dominant alleles drive recessive alleles out of populations?
G.H. Hardy and W. Weinberg, in 1908, studied allele frequencies in a gene pool
in a large population in which there is random mating, and in the absence of forces that change allele frequencies, the original genotype proportions remain constant from generation to generation
because the proportions do not change, the genotypes are said to be in Hardy-Weinberg equilibrium
If the allele frequencies are not changing, the population is not evolving

30. Genetic Change Within Populations: The Hardy-Weinberg Rule
The Hardy-Weinberg equilibrium only works if the following five assumptions are met
The size of the population is very large or effectively infinite.
Individuals can mate with one another at random.
There is no mutation.
There is no immigration or emigration.
All alleles are replaced equally from generation to generation (natural selection is not occurring).

31. Evolution as Genetic Change in Populations
Natural Selection acts on the Phenotype not the Genotype!!! Natural selection can change the relative frequency of alleles in a population over time by selecting individuals with favorable phenotypes (observable adaptations that can be physical or behavioral)

32. Natural Selection on Polygenic Traits
Three Types of Natural Selection that affect polygenic traits
Directional Selection
Stabilizing Selection
Disruptive Selection

33. Directional Selection
When individuals at one end of the bell-shaped curve have a higher fitness.
This causes the curve for a polygenic trait to shift to the left or to the right.

34. Stabilizing Selection
Individuals near the center of the bell-shaped curve have a higher fitness.
The shape of the curve stays the same, but is narrowed.

35. Disruptive Selection
Individuals at the upper and lower ends of the bell-shaped curve have higher fitness than individuals near the middle.

36. Genetic Drift Genetic Drift is a source of evolutionary change.
Some alleles become more or less common by chance.
Occurs in small populations

37. Speciation Speciation- formation of new species
When two populations cannot interbreed and produce fertile offspring, they are reproductively isolated.
3Types of Reproductive Isolation:
Behavioral Isolation
Geographic Isolation
Temporal Isolation

38. Behavioral Isolation Different courtship rituals
Different ranges in mating songs

39. Geographic Isolation
Two populations are separated by geographic rivers.
Ex. Rivers, mountains, bodies of water

40. Temporal Isolation Reproduction occurs at different times
Example: Flowers release pollen on different days

41. Speciation in Darwin’s Finches
Darwin’s finches on the Galápagos are an example of adaptive radiation
in adaptive radiation, a cluster of species changes to occupy a series of different habitats within a region
each habitat offers different niches to occupy
a niche represents how a species interacts both biologically and physically with its environment in order to survive
each species evolves to become adapted to that niche

43. What Is Ecology? Levels of ecological organization 1. Populations
individuals of the same organism that live together are members of a population
2. Species
a species consists of all the populations of a particular organism
3. Communities
populations of different species that live together in the same place constitute a community
4. Ecosystems
a community and the nonliving factors with which it interacts is called an ecosystem

44. What is ecology? Levels of ecological organization 5. Biomes
major terrestrial assemblages of plants, animals, and microorganisms that occur over wide geographic areas and have distinctive physical characteristics are called biomes
6. Biosphere
all the world’s biomes, along with its marine and freshwater assemblages, together constitute an interactive system called the biosphere

45. Levels of Organization
Biosphere
Biome
Ecosystem
Community
Population
Species

46. Biosphere

47. Biome

48. Ecosystem

49. Community

50. Population

51. Species

52. Niche and Competition The niche concept
a niche defines an organism’s biological role
it describes a pattern of living
a niche is the sum of all the ways an organism uses the resources of its environment, including space, food, and many other factors
Figure 2.17 The zebras fill a niche in this African savanna community

53. The Niche and Competition
Sometimes organisms cannot fully occupy their potential niche because some other organism is using it
Competition occurs when two organisms attempt to use the same resource
Interspecific competition – competition between members of different species
Intraspecific competition – competition between members of the same species

54. Predation
One potential and important interaction in a community involves one organism eating another—called predation
Both predators (i.e., the eaters) and prey (i.e., the eaten) may undergo reciprocal evolutionary adjustments
this process is called coevolution

55. Symbiosis
Symbiosis is an interaction in which two or more kinds of organisms interact in a close relationship
the relationship types vary by whether or not each participant is unaffected (0), helped (+), or harmed (-)

56. Types of Symbiosis
+/0 Commensalism
+/- Parasitism
+/+ Mutualism