Download Study Guide Evolution Chapter 14

Study Guide Evolution Chapter 14
Evolution
1. Species change over time.
2. Ancestral Species of past gave rise to new species of today.
3. Lamarck proposed the 1st important theory of evolution in 1809
4. Darwin explained evolution by natural selection by ‘Descent with Modification’ in 1859
5. Microevolution is favorable change in a population that helps it to survive and reproduce better in
its ecosystem. It leads to a biological adaptation.
6. Macroevolution is origin of a new species from ancestral species.
7. Gradualism means very slow but steady rate of evolution over millions of years.
8. Punctuated Evolution means long spells of little or no change intervened by short spans of fast
change.
9. Fossils are remains or imprints of organisms living in remote past.
10. Fossils provide best evidence for evolution.
11. Other evidences come from anatomy, embryology and molecules
12. The anatomical record also reflects evolutionary history
13. For example, all vertebrate embryos have similar early development
Homoogous Structures
1. Share Common ancestry and basic plan
2. Same structures used for different
functions
3. Leads to divergent evolution
4. For example bones of forelimb, hindlimb
or skull
5. Used as a basis for classification
Analogous Strucutures
1. Different ancestry and basic plan
2. Different structures used to do similar
function
3. Leads to convergent evolution
4. For example wings of insects and birds
5. Leads to artificial groups if used in
classification
Evolution at molecular level
14. Molecules like DNA, RNA and proteins have records of evolutionary history = phylogeny
15. Closely related organisms like chimps and humans separated in near past and have lesser
differences in arrangement of amino acids in proteins or nucleotides in nucleic acids
16. Number of differences increase steadily as we move from closer to distant related species.
5 Agents of Evolution
1 Mutation
17. Mutation is the change in nucleotide sequence of a gene or chromosome.
18. Mutation rate is very low
19. Most mutations are harmful
20. Mutation is the ultimate source of variations
21. For example, sickle-cell-anemia is a single nucleotide mutation in hemoglobin gene
2 Migration or Gene Flow
22. Occurs due to movement of individuals from one population to another
23. Depends on # of individuals and what kind of genes they carry
3 Genetic Drift
24. Explains role of chance in evolution
25. Operates best in small and endemic populations
26. Brings different results from natural selection
27. Founder Effect is when some individuals colonize a new area.
28. Bottleneck effect is population size gets very small and regains its size.
4 Non-random mating
29. Selection in mating results in changes in gene frequencies
30. Mostly females chose their partners favoring different traits in different species
31. Horns in deer and colored feathers in birds reflect a healthy genotype
5 Selection
32. Natural Selection operates by Favorable allele  more survival  more reproduction  more % in
next generation
33. For example, Resistance allele against DDT or antibiotic
34. Artificial Selection by humans has lead to formation of different breeds in dogs and varieties in
plants – cabbage and cauliflower
3 kinds of Natural Selection
35. Stabilizing NS operates when environment is stable and population is already adapted. Changes are
not welcome; middle favored.
36. Disruptive NS operates when large changes occur in environment. Middle eliminated and ends
favored; lead to formation of new species.
37. Directional NS operates when environment changes gradually in 1 direction. One end eliminated
other favored. DDT resistance.
38. Sickle-Cell Anemia
39. Glutamic acid is replaced by Valine in position 6 out of 146 amino acids in β chain of hemoglobin
40. Reduces life span of RBC’s
41. Change shape only under stress
42. Macroevolution: origin of a new species = Speciation
43. Raw Material: Genetic variations: provided by mutation, independent assortment and
recombination (crossing-over).
44. Driving Forces are primary Natural selection and secondary genetic drift.
45. End product: Reproductive Isolation leads to Speciation. Pre-zygotic and Post-zygotic.
46. Reproductive Isolation
47. Allopatric speciation – populations live in different geographical area
48. Sympatric speciation – same geographical area; populations are isolated due to use of different
parts of habitat or have different breeding seasons (ecological isolation)
Polyploidy (3n or more)
49. Plants can tolerate extra genomes of chromosomes
50. Increase in # of genomes usually produces bigger plants or parts like flowers or fruits
51. Polyploidy is a type of instant speciation
52. Bread Wheat has 6n chromosomes in it.