BILD3 Midterm 1

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BILD3 Midterm 1
2013-12-12 00:19:30
Organismic Evolutionary Biology

Evolution & Speciation
Show Answers:

  1. Microevolution (definition)
    • Change in allele frequency of a population over time
    • Across generations
    • Within a species
    • Small-scale evolutionary change
  2. Population (definition)
    Group of individuals from the same species, that live in the same area, and have the ability to mate
  3. 3 Main Types of Mutations
    • 1. Point Mutations
    • 2. Insertions & Deletions (Frameshift Mutation)
    • 3. Macromutations
  4. 3 Assumptions of Microevolution
    • 1. Variation of traits in population
    • 2. Traits are heritable (Changes must pass on through DNA)
    • 3. Not all offspring reproduce equally
  5. Types of Point Mutations (3 groups, 2 sub-groups)
    • 1. Silent: One nucleotide change but gives same amino acid. Same function.
    • 2. Missense: One nucleotide change gives change in amino acid. 2 Types:
    •  - Conservative: Same function (-) to (-)charge
    •  - Non-conservative: Different function (+) to (-) charge, for example
    • 3. Nonsense: One nucleotide change leads to a STOP codon. Most destructive.
  6. Frameshift Mutations / Insertions & Deletions
    • RNA is translated by the codon in sets of 3 nucleotides
    • One insertion or deletion could change reading of the remaining
    • LEAST IMPACT with multiples of 3 since won't change the others
  7. 3 Types of Macromutations
    • 1. Chromosome inversion: Break in strand & flipped. Could change regulation of a gene.

    • 2. Gene duplication: During crossing over, copied at different locations. Result is one daughter chromosome missing, one duplicated
    • 3. Polyploidy: Duplication of entire genome. Offspring would have 92 chromosomes. More in plants.
    • p
  8. Phenotype
    Expressed physical trait
  9. Genotype
    Genes/alleles. Genetic composition.
  10. Heritability Equation
    • =   Genetic variation    
    •   Phenotypic variation

    • If gen = phen, 1 heritability
    • If gen ≠ phen, 0 heritability
    • BMI = .5 gen+phen

    • ex. Herit= .8 high heritability.
    • Herit= .3 high environmental
  11. Hardy-Weinberg Equilibrium
    • p²+2pq+q² = 1
    • Used as null model

    • p = Allele freq of dominant homoygotes
    • q = Allele freq of recessive homozygotes

    • p² = Genotype (combination of genetic traits) of dominant homozygotes
    • 2pq = Genotype (combination of genetic traits) of heterozygotes
    • q² = Genotype (combination of genetic traits) of recessive homozygotes
  12. Hardy-Weinberg Assumptions: (5)
    • 1. No natural selection
    • 2. Mating is random (panmictic)
    • 3. Population is infinitely large
    • 4. No gene flow from outside population
    • 5. No mutation

  13. Natural Selection (definition)
    • Differential success in reproduction,
    • Results in favored alleles increasing in future generations
  14. Evolutionary Fitness
    • The relative proportion of an individual's genes among all genes of the next generation
    • High fitness = more gene copies to next gen.
  15. Indirect Fitness
    Family passing off genes

    ex. Menopause is an adaptation to stop reproduction & raise offspring of other family (indirect fitness benefit)
  16. The Nature of Selection (4)
    • 1. Acts on individuals, results seen in populations
    • 2. Acts on phenotypes, but only genotype is heritable
    • 3. Only acts on variation in a population (it's random & not perfect)
    • 4. Not forward looking or progressive. It can't plan ahead
  17. 3 Types of Selection:
    • 1. Directional Selection= Favors extreme of one phenotype ex. salmon getting smaller

    • 2. Stabilizing selection= Favors the intermediate phenotype. ex infant mortality

    • 3. Disruptive Selection/divergent= Favors phenotypes of both extreme. ex finches w/small and large beaks better for seeds
  18. Balancing Selection
    • (Similar to disruptive selection)
    • Occurs when natural selection maintains stable frequencies of 2 or more phenotypic forms of a population
    • Leads to state called balanced polymorphism
  19. Aposematic
    • Color mimicry (black & yellow) to ward off predators
  20. 2 Types of Balancing Selection (+2 subgroups):
    • 1. Heterozygote Advantage= heterozygosity at certain locus means greater fitness
    • Natural selection keeps 2+alleles @ locus
    • ex. Sickle Cell Allele (due to missense mutation)
    • 2. Frequency-Dependent Selction= Fitness of phen. depends on phen. frequency in population
    • 2 Types:
    • - Negative: Higher the frequency, lower the fitness
    • ex Cichlid fish mouth on either side
    • - Positive: Higher frequency, higher the fitness
    • ex. Aposematic (coloration mimicry) like black & yellow to warn predators.
  21. Sexual Selection
    • Non-panmictic (not random mating)
    • The preference of a particular phenotype in the mating decision of females and males.
    • Females = Choosier. Choice based on sexually selected traits
    • ex. peahen chosing male peacock for his tail
    • Males = More promiscuous. If able to survive the bright displays, shows better survival traits. Male competition
    • ex. male bowerbirds competing for best decorated dens
  22. 3 Components of Genetic Drift
    • Sampling Error: Smaller the population, the bigger the impact of drift
    • Bottleneck Effect: Environment change can drastically effect gene poolex. Achromatopsia (colorblindness) & cheetahs.
    • Founder Effect: When some individuals of a population become isolated. Can affect allele freq of a population 
    • ex. colonizing an island
  23. Genetic Drift
    • The change in genetic composition of a population due to chance events.
    • Happens in VERY SMALL populations
  24. Independent Assortment of Chromosomes
    (1 Method of Variation)
    • Occurs during meiosis (metaphase)
    • Human can have 84 million chromosome combinations from 23 pairs!

  25. Crossing Over
    (1 Method of Variation)
    • Occurs during meiosis (prophase)
    • Usually happens when matching regions on matching chromosomes break and reconnect to other chromosome.
  26. Meiosis
    Cell division. (2n in half=4 gametes)

    • 1. Diploid (2n parent cell) has 2 copies of each chromosome. The pairs of homologous chromosomes (meaning 1 set from each parent) are divided in half to form haploid cells at random. Each haploid cell has genes from mother & father= sister chromatids.
    • 2. Each haploid cell splits in 2, still haploid.They can mature into gametes (a cell that fuses with another during fertilization. Becomes either egg or sperm).
  27. Syngamy
    • Fertilization process
    • The fusion of two cells, or of their nuclei, in reproduction.
    • Result is a zygote
  28. Gene Flow
    • Migration causes movement of alleles b/w populations
    • Movement of fertile individuals or gametes
    • Reduces differences b/w population over time, homogonizing overall genepool.

    • ex. pollen from plants.
    • Great Wall of China= Less gene flow across Great Wall than across small mountain path, less gene flow within insect pollinated species than wind pollinated species
  29. Polymorphism
    Genetic variation that produces differing characteristics in individuals of the same population or species.

    • ex. ants in same species but worker, queen & drone all different morphs or forms
  30. The "Biological Species Concept" definition of a Species
    • Ernst Mayr
    • Population/ group of populations whose members have the potential to breed in nature & produce viable fertile offspring
    • (this definition doesn't always work)
  31. Reproductive Isolation
    • aka Evolutionary Independence: not exchanging biological material.
    • The existence of biological factors that prevent members of 2 species from producing viable, fertile hybrids

    ex. horse+donkey=mule ?
  32. Limitations of the Biological Species Concept
    • Can't be applied to:
    • - Asexual organisms
    • - Fossils
    • - Organisms whose reproduction is hard to study
    • Also DNA samples are COSTLY
  33. 2 other definitions of Species
    • 1. Morphological Species Concept= If it looks the same, it is the same. Characterizes by body shape, size & other structures.
    • 2. Phylogenetic Species Concept= Independent units. Looks at organisms with unique genetic history.
  34. Limitations with the Morphological Species Concept:
    • It's easier but not always accurate due to:
    • a. similarities between species (ex. species of finches)
    • b. diversity within species (ex. humans)
  35. Cryptic Species
    Type of morphospecies. Species that look the same but don't share alleles

    • ex. copepod looks same here and Japan, but no shared alleles in millions of yrs
  36. The Phylogenetic Species Concept AND Limitations
    • Can use molecular data, not behavioral, to track movement of alleles & infer lack of gene flow
    • Applies to all organisms even asexual & fossils
    • Limitations:
    • Good methods not available for most organisms (yet)
    • Very expensive & costly
  37. Summary of Mechanism of Speciation
    • 1. Genetic isolation (allopatric or sympatric)
    • 2. Genetic divergence. Once the genes were isolated from one another they could continue to diverge into a new species through genetic drift and natural and sexual selection
  38. Allopatric ("Other Country") Speciation
    • Gene flow interrupted or reduced when population is divided into different geographical locations

    • ex. Hawaiian islands & hundreds of different species of fruit flies
  39. Vicariance
    • (Form of Allopatric Speciation)
    • The separation/division of a group by a geographic barrier, like mountain or water

    • ex. Grand Canyon & different species of chipmunk
  40. Sympatric ("Same Country") Speciation
    • RARE!
    • Divergence & speciation without geographic isolation
    • Difficult b/c genes causing divergence must be linked to or same as those causing reproductive isolation (They are still able to mate, but must choose to not breed together, preferentially)

    ex. Fruit flies for Apple trees and Hawthorn trees. Different species, same area. Must lay eggs at different times depending on fruit (host)
  41. Polyploidy (& its 2 levels):
    • (Results in Sympatric Speciation, plant species)
    • Extra chromosomes due to accidents during cell division

    • 1. Autopolyploidy: From 1 Species.
    • Failure of cell division of growing diploid plant after chromosome duplication makes other tissue. Gametes will be diploid.

    • 2. Allopolyploidy: From 2 Species.
    • A=2n=4. B=2n=6. Meiotic error, 4 chrom +3 =Hybrid w/7 chromosomes. 7 + gamete with 3 =10, even #. Can reproduce w/another 10.
  42. How Seedless fruits are made:
    • - Female tetraploid (3 chrom) mixed with male diploid (2) produces triploid seeds
    • - Triploid seeds grow into plants -> produce watermelons
    • - In Triploid plants- 3 copies of chromosomes can't be divided evenly in meiosis
    • - Triploid watermelons don't contain mature seeds
  43. Possible outcomes of Secondary Contact
    (If species after split run into each other again)
    • 1. Reinforcement
    • 2. Stability
    • 3. Fusion
  44. Secondary Contact (could)= Reinforcement & Stability = Reproductive Isolation. Due to 2 types of barriers...
    • 1. Prezygotic Barriers= Barrier before fertilization
    • ex. temporal, behavioral, habitat isolations

    • 2. Postzygotic Barriers= Egg fertilized but unsucessful. Prevents hybrid zygote from developing into viable, fertile adult
    • ex. horse+donkey=mule
  45. Secondary Contact (could)= Hybrids. What happens if no reproductive isolation? Either..
    • -Hybrid = equal fitness = coalescence (fusion)
    • -Hybrid = higher fitness = new species

    • ex. big sagebrush
  46. Macroevolution (definition)
    Evolutionary change at or above the level of species
  47. Phylogeny
    • Is a hypothesis of the evolutionary history of a species or group of related species (the tree!)
  48. How many millions of years ago did plants colonize land?
    = 475 Million Years Ago
  49. How long ago did life begin on earth?
    = 2.7 to 3.7 BILLION years ago
  50. Systematics
    Classifies organisms & determines the evolutionary relationships (the science of making the trees!)
  51. Categories of Classification
    (by Carolus Linnaeus)

    • (Dumb Kings Play Chess On Fat Girls' Shoes)
    • (Dammit Kitty, Please Come Out For Goodness Sakes!)
  52. The 2-part scientific name of a species is called a:
  53. The 1st & 2nd part of the scientific name of a species are:
    • 1st = genus 
    • 2nd = epithet

    Homo-sapien or Homo-sapien
  54. Evolution (Scientific definition)
    A change in the genetic composition of a population over generations
  55. Typological Thinking
    • Thought original copy w/random errors
    • Aristotle
    • Philosophical, not religious
    • "Historia animalium"- Thought of species as types, behavior as instinctual
    • Ruled Western biological thinking for over 2,000 yrs
  56. 4 Parts of Theory of Special Creation (16th - 19th Century)
    • 1. Linear Progression "The Great Chain of Being" God-Angels-People-Wild Animals-Domestic Animals-Plants
    • 2. Species were created independently of ea.other
    • 3. Species don't change over time..No evolution, no extinction. 
    • 4. Species were created recently
  57. Carolus Linnaeus
    • Founder of taxonomy (classified)
    • Anti-Evolutionist
  58. Georges Cuvier
    • French Paleontologist
    • Believed in catastrophism= Series of large events that reinvented new species
    • Anti-evolutionist
  59. James Hutton & Charles Lyell
    (Hutton & Lyell)
    • Geologists 
    • Great influence on Darwin
    • Believed in Gradualism & Uniformitarianism= Gradual processes & same in past & today.
    • Requires earth much older than biblical account
  60. Jean Baptiste Pierre Lamarck
    • French Biologist
    • EVOLUTION (published year Darwin born) 1809
    • Called "Inheritance of Acquired Characteristics"
    • 1. Use/Disuse- Appendages, organs can change w/use, deteriorate w/disuse
    • 2. Changes are inherited

    • ex. Giraffe's neck. Mechanism was wrong, but 1st to suggest species could change over time
  61. Epigenetics
    Experiences may affect our DNA

    ex. environment changing genes like mouse diet affecting agouti gene, affecting fur color, weight, & likeliness to develop cancer
  62. Thomas Malthus
    • Economist
    • "Survival of the Fittest"
    • Believed human growth exponential, food resources limited
  63. Darwin's Voyage on the Beagle
    (4 most influential visits)
    • 1. Cape Verde Islands
    • Rock w/marine shells 45 ft above ground (white sedimentary rock)
    • Idea: Once underwater. Uniformitarianism & Gradualism began to sink in while reading of Hutton & Lyell.
    • 2. Brazil
    • Discovered bones of giant ground sloth, armadillos, etc (extinct).
    • Idea: They were similar to living forms
    • 3. Chile
    • Andes- Found marine shells at 12,000 ft
    • Volcanic eruption raised coastal shelf by 8ft.. in ONE DAY
    • 4. Galapagos Islands 
    • Geopgrahpically isolated. Species there for millions of years. Galapagos tortoise: dome-shaped carapace w/low front. Endemic= Species live only in 1 area. Large island w/ low vegetation, don't have predator threat (Santa Cruz, Isabella) Tortoise w/longer neck & front to reach hgher vegetation
  64. "On the Origin of Species" (1859)
    • Sold out the first day
    • Convinced leading scientists immediately

    • What it states:
    • 1. Descent w/modification ("evolved", but only uses term once at end of book)
    • 2. Mechanism - Natural selection - differential survival/reroduction

    • Initially:
    • 1. Evolution accepted
    • 2. Natural Selection rejected (didn't have proper evidence)
  65. Evidence of (Macro)Evolution (6 Groups):
    • 1. Law of Succession (Fossils of living similar to fossils of extinct)
    • 2. Transitional Fossils 
    • 3. Common Ancestors
    • 4. Homology
    • 5. Genetic Code
    • 6. Vestigial Stuctures & Organs
  66. Law of Succession
    • (Evidence of Evolution at level of species/ Macroevolution)
    • Fossils in 1 region similar to living organisms in that region
    • Darwin noted similar pattern in Argentina

    • ex. Extinct Glyptodont & living Pygmy Armadillo
  67. Transitional Fossils
    • (Evidence of Evolution at level of species/ Macroevolution)
    • Used as "missing links"
    • Dinosaurs -> Birds
    • Fishes -> Tetrapods
    • Tetrapods -> Whales

    • ex. Archaeopteryx= transitional b/w dinosaur & bird. Was reptile with FEATHERS. Germany, 145-150 Million Yrs Ago
  68. Homology (2 Types):
    • (Evidence of Evolution at level of species/ Macroevolution)
    • Study of Linkeness

    • 1. Structural Homology
    • Mammilian forelimbs have same basic structure, even w/different functions.

    • 2. Developmental Homology
    • Similarities during development, even if different as adults.
    • ex. human embrios have gills, turn into voicebox & tail remnants
  69. Vestigial Structures & Organs
    1. Vestigial Structures: DID have purpose in ancestor. Not costly enough to disappear.

    • ex. Pelvis bone in whales

    2. Vestigial Organs

    ex. flightless birds, goosebumps in humans
  70. Convergent Evolution
    & Analagous Features
    • Opposite of Homology
    • Independent evolution of similar features in different lineages. Resembled features are analogous, not homologous b/c similar function, not ancestry.

    ex. flying squirrel & sugar glider = Analagous
  71. 3 Principles of Natural Selection
    (hint: SAME as principals of Microevolution)
    • 1. Variation w/in a trait
    • 2. Variation is heritable
    • 3. Not all individuals reproduce equally
  72. Lord Kelvin's Theory
    (1st Reason why natural selection not easily accepted)
    • Assumed earth began as molten rock around 7000 degrees F
    • Knew size of earth & that temp's increase 1 degree for every 50ft of depth
    • Estimated age of earth as 100 million years old based on equation of heat loss

    *This estimate was off b/c Radioactive core made earth constantly heating, not cooling.
  73. Thomas Morgan & Mutation
    • Refuted idea of no mechanism of novel creation that tried to discredit natural selection
    • Nobel prize in 1933
    • Worked w/fruit flies
    • Previously, mutations were thought to be large, causing speciation
    • Morgan showed mutation, mechanism, & effect on body
  74. Weissman & "Soft Inheritance"
    • Weissman: Discredited Lamarckism (acquired characteristics) w/ infamous mouse tail clipping experiment, showing tails chopped don't effect offspring. Inherited characters are from genes of successful parents
    • Refuted idea of no mechanism of inheritance that tried to discredit natural selection
  75. No mechanism for the creation of novel variation
    (2nd Reason why natural selection not easily accepted)
    • 1. Creationism: God creates variation or random imperfections
    • 2. Orthogenesis: Natural tendency towards complexity & perfection w/ humans @ top
    • 3. Transmutationism: Variation in large amounts in short amounts of time
    • 4. Lamarckism: Acquired charachteristics
    • ex. Giraffe necks
  76. No mechanism for the inheritance of adaptations (3rd Reason why natural selection not easily accepted)
    • Ideas:
    • 1. Lamarckism
    • 2. Blending= Any beneficial adaptation will be diluted & eventually disappear
  77. Gregor Mendel
    • Inheritance
    • Founder of science of genetics
    • "Mendelian Inheritance"

  78. Homologous trait or Analogous Trait?

    1. Flight in birds and bats 
    2. Forelimb bone structure in whales, cats, and bats
    3. Yellow and black coloring in poison dart frogs and wasps
    4. The genetic code of Archaea and European starlings:
    • Analogous
    • Homologous
    • Analagous
    • Homologous

  79. The height of parents and offspring were measured in three populations and graphed. If selection began to favor the shortest individuals, in which population would height evolve fastest?
  80. Selection & genetic drift tend to ___________ genetic variation
    = Reduce
  81. Mutation, diploidy, neutrality, gene flow, & balancing selection can maintain genetic _____________ in a population.
    = Variation
  82. ____________ are the ultimate source of genetic variability.
    = Mutations
  83. ____________ & sexual reproduction result in novel genetic combinations
    = Recombination
  84. Recombination (definition)
    The process or act of exchanges of genes between chromosomes, resulting in a different genetic combination and ultimately to the formation of unique gametes with chromosomes that are different from those in parents.
  85. Polyploidy only occurs in plants (True/False).

    It is possible for polyploidy to cause a speciation event in only two generations (True/False).
    • False.
    • True.
  86. Which statement(s) about peppered moths in England is(are) true?

    a. In response to increased pollution, the mutation rate increased, which created more black morph individuals.

    b. Environmental change before and after the Industrial Revolution altered the fitness of individuals with the white and black phenotype.

    c. Directional selection changed the distribution of color phenotypes in the peppered moth population.
    = B & C
  87. Which of the following statements is not always true of a population of sexually reproducing animals:

    a. A group of individuals that can potentially mate.

    b. A group of individuals that occur in the same geographic region.

    c. A population does not exchange genetic material with other populations of the same species.

    d. Hardy-Weinberg equilibrium predicts genotype frequencies within a non-evolving population.
    = c. A population does not exchange genetic material with other populations of the same species.
  88. Sickle-cell Anemia is caused by what type of mutation?
    Point mutation / base-pair substitution
  89. Which is correct?

    Environment + Genotype = Phenotype
    Environment + Phenotype = Genotype
    Environment + Genotype = Phenotype
  90. Examples of:
    A. Pre-mating isolation mechanism
    B. Post-mating pre-zygotic isolation mechanism
    C. Post-zygotic isolation mechanism
    • A. Pre-mating isolation mechanism :
    • Behavioral isolation, habitat isolation, temporal isolation
    • B.  Post-mating pre-zygotic isolation mechanism 
    • Mechanical isolation, gametic isolation (sperm doesn't lock to egg), 
    • C.  Post-zygotic isolation mechanism
    • Reduced hybrid viability (ex. salomander), reduced hybrid fertility (ex. mule), hybrid breakdown (ex.grass can reproduce but problems in environment)
  91. Some of the earliest documentation loosely describing evolution by natural selection is seen:
    a. during the Enlightenment
    b. in the writings of Aristotle on Empedocles c. from 14th Century Chinese scholars
    d. in the writings of Lamarck
    e. in the writings of Darwin
    b. in the writings of Aristotle on Empedocles
  92. 4. (4pts) Which of the following did Darwin NOT see during his voyage to the Galapagos?
    A. Numerous non-endemic species with body types that seemed well-suited to the local environment.
    B. Finches that varied in beak size and this variation corresponded to the size of available food resources
    C. Tortoises that had shorter necks and lower arched carapaces on wetter, more lush islands.
    D. Mockingbirds that significantly differed between islands
    e. All of the above DID occur
    A. Numerous non-endemic species with body types that seemed well-suited to the local environment. 

    (He saw ENDEMIC; living)
    (this multiple choice question has been scrambled)
  93. Is it more common for a point mutation to have a negative impact on fitness than a positive impact?
  94. As environmental variation increases, the heritability of a trait will decrease. This statement is:
    A. Possibly true. We first must know the effect of environmental variation on genotype.
    B. Possibly true. We first must know the effect of environmental variation on phenotype.
    C. False
    D. True
    B. Possibly true. We first must know the effect of environmental variation on phenotype.
    (this multiple choice question has been scrambled)
  95. 14. (6pts) For each of the following mechanisms of evolution, list the assumption(s) of HWE that it violates.

    • Genetic Drift: ________________
    • Sexual Selection: _____________
    • Gene Flow: __________________
    • infinite pop size
    • random mating
    • no migration
  96. T / F Oxygen was initially released into the atmosphere primarily as a by-product of protist photosynthesis.
    False -  photosynthetic prokaryotic organisms that emitted O2 as a waste product. (Protist = Eukaryotic)
  97. The largest mass extinction event in history occurred approximately
    A. 250 million years ago
    B. 1.5 billion years ago
    C. 65 million years ago
    D. 100 years ago and still continues
    A. 250 million years ago 

    Permian–Triassic (P–Tr) extinction event.
    The earlier phase was probably due to gradual environmental change, while the latter phase has been argued to be due to a catastrophic event.
    (this multiple choice question has been scrambled)
  98. Examining the phenotypes of a population of nargles, you find that they are exceptionally transparent. Nargles have a greater chance of survival than somewhat transparent or opaque nargles. This type of selection is cosidered to be:

    A. disruptive
    B. frequency-dependent
    C. directional
    D. stabilizing
    E. sexual
    C. directional
    (this multiple choice question has been scrambled)
  99. Which of Charles Darwin's influences established extinction as fact through his work with fossils?

    A. James Hutton
    B. Thomas Malthus
    C. E.O.Wilson
    D. Jean-Baptiste Lamarck
    E. Georges Cuvier
    E. Georges Cuvier
    (this multiple choice question has been scrambled)
  100. A fossil of a giant sloth is found in an area & resembles other extant organisms living in the same place. This is an example of:

    A. the Law of Succession
    B. vestigial structure
    C. artificial selection
    D. Paleontological morphology
    E. developmental homology
    A. the Law of Succession
    (this multiple choice question has been scrambled)
  101. Which of the following does NOT tend to promote speciation?
    A. disruptive selection
    B. polyploidy
    C. the founder effect
    D. natural selection
    E. gene flow
    E. gene flow
    (this multiple choice question has been scrambled)