Evolution Study Guide

Justin Huang, David Uchime

Principles of Evolution

1. Evolution is the process of biological change by which descendantscome to differ with their ancestors
2. According to Jean-Baptiste Lamarck, organisms acquired traits bypassing on larger or smaller structures based on greater usage, and that changes in the environmentcaused the change.

1. This was known as the inheritance of acquired characteristics
2. Example: Lamarck thought that giraffes grew longer necks becausethey needed to reach leaves higher and higher in trees

3. Theories of geologic change

1. Catastrophism: natural disasters such as floods and volcaniceruptions have happened often during Earth’s history and caused species to go extinct
2. Gradualism: changes observed in landforms happen slowly over a longperiod of time

1. Applying this to evolution means that organisms evolve slowly overtime
2. Proposed by James Hutton

3. Uniformitarianism

1. States that the geologic processes that shape the Earth are uniformover time
2. Combines the theory of Hutton with Lyell’s own observations

4. Part of uniformitarianism was that the Earth is changing at auniform rate and is still ongoing, and it greatly affected Charles Darwin
5. Darwin was shocked by the variation of traits among similar species,especially in the Galapagos Islands
6. In the Galapagos Islands,

1. Saddle-backed tortoises (long necks and legs) lived in areas with alot of tall plants
2. Domed tortoises (shorter necks and legs) lived in wet areas withrich mosses and short plants
3. Finches with strong, thick beaks lived in areas with manyhard-shelled nuts
4. Finches with more delicate breaks were found where insects or fruitswere widely available

7. Artificial Selection: the process by which humans change a speciesby breeding it for certain traits
8. Natural Selection: mechanism by which individuals that haveinherited beneficial adaptations show differential reproductive success
9. Survival of the Fittest: the strong survive and are able to producemore offspring
10. The environment favors organisms that have higher fitness

1. Fitness: the ability of an organism to survive and produce moreoffspring

11. Things that can be learned because of a fossil record include

1. If an organism existed at all
2. When an organism lived
3. The order in which organisms lived
4. Support for Darwin’s theory of descent withmodification

12. Law of Superposition: older rock layers and fossils are more deepinside the ground than newer fossils and rock which is higher
13. Biogeography

1. Defined as the study of the distribution of organisms around theworld
2. Biogeography is used as evidence for evolution because it providesevidence of how and when a species evolved

14. Homologous Structures vs Analogous Structures

1. Homologous Structures: features that are similar in structure butappear in different organisms and have different functions

1. Ex. human hands, bat wings, and mole feet have similar structuresbut they all perform different functions. This is as a result of a common ancestor

2. Analogous Structures: structures that perform similar functions butare not similar in origin

1. Ex. bat wings and fly wings both perform the same function, but theycame from different structures
2. Not a sign of common ancestor

15. Vestigial Structure

1. Remnants of organs or structures that are found in early ancestorsthat no longer serve a useful function or serve a completely different function
2. Ex. human tailbone, pelvic bones and hind limbs in snakes

16. Paleontologists find the fossils, geneticists compare relatedness bychecking DNA of living and sometimes nearly fossilized organisms. Each new advance in either fieldcontinues to verify the the overall theory of evolution and fill in missing details
17. Protein comparison helps determine relationships of ancestors bylooking for homologous sequences, and if they had the same protein, then they are most likelyrelated.
18. Phylogeny: a history of evolution of organisms in a species or groupof organisms

1. Represented by a tree
2. Be able to read a cladogram

Evolution of Populations

19. Allele frequencies measure the Genetic variation in a genepool.
20. Genetic Variation increases the probability that some members of apopulation will have a trait that helps them survive and reproduce.
21. The two main Sources of Genetic variation are

1. Mutation: a random change in the DNA of a gene
2. Recombination: Crossing over in Prophase 1 that causes new allelecombinations.

22. Microevolution is a small change within a species over a shortperiod of time
23. Macroevolution is a big change in species over a long period oftime
24. Types of selection

1. Directional selection is natural selection that favors one traitover another
2. Stabilizing selection is when selection favors the intermediatephenotype
3. Disruptive selection favors the extreme phenotypes over theintermediate phenotypes.

25. Gene flow is the movement of alleles through different populations.

1. Low gene flow increases the chance that two populations will evolveseparately while high gene flow decreases the probability that two populations will evolveseparately.

26. Genetic drift is a change in allele frequencies due to chance. Itcan be caused by a bottleneck effect (natural disaster) or the founders effect (a few members of apopulation moving to a new area)
27. Two types of sexual selection

1. Intersexual: males display traits to attract females.
2. Intrasexual: males display traits to compete against othermales.

28. The Hardy-Weinberg equilibrium is a model that shows how populationswill change over time. The Hardy-Weinberg equation is used to predict genetic frequencies in apopulation
29. Five traits that lead to lack of genetic variation

1. very large population: no genetic drift
2. no emigration or immigration: no gene flow
3. no mutations: no new alleles added to gene pool
4. random mating: No sexual selection
5. no sexual selection or no natural selection: all traits aid equallyin survival.

30. Speciation is the creation of new species through naturalselection and
31. Reproductive isolation increases the chance that to populations willevolve separately and creates new species
32. Types of reproductive isolations

1. Behavioral isolation: caused by differences in behaviors likecourtship rituals
2. Geographical isolation: caused by a geographic barrier
3. Temporal isolation: caused by differences in reproductivecycles.

33. Types of evolution

1. Convergent species are where two different species becomesimilar
2. Divergent evolution is where two different species become different.
3. Coevolution is two or more species evolving together

34. Mass extinctions are rarer but more intense than normalextinctions
35. Speciation patterns

1. Gradualism: slow but steady change
2. Punctuated equilibrium: period of little to no change followed byperiod of rapid change
3. Adaptive Radiation: Where one species evolves into several differentspecies

History of Life

36. Nebular hypothesis: solar systems were created by nebulas
37. Cyanobacteria were bacteria that could carry outphotosynthesis

1. Cyanobacteria is a prokaryotic cell
2. Over 3.5 billion years old
3. By photosynthesizing, they were able to create oxygen as abyproduct

38. Endosymbiont theory: mitochondria and chloroplasts were once simpleprokaryotic cells that were engulfed by larger prokaryotic cells, but some did not get digested andinstead became a part of the cell
39. The Devonian period was known as the “Age ofFishes”
40. The Mezezoic era was known as the “Age ofReptiles”
41. The Cenozoic era was known as the “Age ofMammals”
42. Mass Evolution wiped out many organisms and paved a way fordifferent organisms to survive