Bio 94

  1. What is a cladogram?
    type of evolutionary tree built on “cladistic” principles
  2. What are the three "cladistic" principles and define them
    • synapomorphies-shared traits of other common ancestors
    • Parsimony –method that implies as few evolutionary steps as possible
    • Coherence –trees built using different synapomorphies should agree
  3. What is a node on a cladogram?
    a branching point
  4. How are cladograms built (3 steps)?
    • 1.) analyzing DNA
    • 2.) looking at synapomorphies
    • 3.) coherence-justification via multiple fields of study
  5. What is a theory?
    a proposed explanation for a very general class of phenomena
  6. What is a hypothesis?
    a proposed explanation for a specific phenomenon or set of observations
  7. What are the three domains of life?
    • archea
    • bacteria
    • eukaryotes
  8. Of the archaea, bacteria, and eukaryotes, which are the two that are closer to each other?
    eukaryotes are closer to archaea
  9. What is the synapomorphy for all eukaryotes?
    membrane bound organelles
  10. What is a scientific theory?
    a proposed explanation for general phenomena that is well suppported
  11. What are the 2 components of a scientific theory and explain what they mean?
    • pattern-what is occuring
    • process-why is this occuring
  12. What is meant by descent with modification?
    • species change over time. different populations of the same species diverge
    • different species are related, not independent creatures
  13. How did we prove descent with modification? (4 ways)
    • 1.) measuring the ages of the earth's strata (layers) via radiometric aging
    • 2.) analyzing fossils
    • 3.) Homologies
    • 4.) Identifying homoplasy aka convergent evolution
  14. What are fossils?
    mineralized remains of organisms
  15. Extant
    a lineage with living representatives
  16. Extinct
    a lineage whose members are all dead
  17. What do transitional fossils tell us? What do they help build?
    • They tell us which species are more closely related, show transition, evolution.
    • Helps us build cladograms
  18. Genetic and molecular homologies tell us...
    species share the same gene
  19. What are homologies?
    similarities in characteristics due to shared ancestry
  20. Define structural homologies
    • physical similarities
    • ex. bones
  21. Define developmental homologies
    embryo similarities
  22. Define genetic and molecular homologies
    similarities in the DNA (genes)
  23. Define homoplasy
    similarities in characteristics due to environment not ancestry
  24. We can insert our DNA into a plasmid and express the same protein because of what?
    genetic homology
  25. We can understand the development of humans via looking at flies. Why is this?
    developmental homologies- different species have similar embryo stages or features, which we can compare
  26. Define allele frequency
    amount or percent of alleles proportional to other alleles in population
  27. Define trait
    any measurable aspect of an organism
  28. What is evolution?
    change in allele frequency within a population over time
  29. Define natural selection
    • certain heritable traits lead to higher reproduction success relative to other individuals in the population
    • that heritable trait is favored
  30. Evolution=______ while natural selection=_______
    population; individuals
  31. Define population
    group of individuals of one species that live in a particular place
  32. What are the four major causes of evolution?
    • mutation
    • genetic drift
    • genetic bottleneck
    • founder effect
  33. Define mutation
    any change in the hereditary material of an organism
  34. Define genetic drift
    a change in allele frequency due to sampling error
  35. In a __________, genetic drift tends to eliminate alleles
    small population
  36. Define sampling error
    • a statistical error in which the sample does not
    • represent the entire population
  37. Define genetic bottleneck
    • sudden loss of individuals or alleles within a population
    • key giveaway: natural disaster
  38. Is genetic bottleneck a form of genetic drift?
  39. Define founder effect
    • establishment or start of a new population
    • new population does not equal old population
  40. What are the four modes of natural selection and define them?
    • directional- favors one extreme trait and pushes the graph to the left or the right
    • disruptive- favors two extreme traits and creates a bump on the left and right
    • stabilizing- favors intermediate traits and pushes the bump in the middle
    • balancing- does not favor any traits, the graph remains the same, no change!
  41. Which of the following modes of natural selection increases genetic variation?
  42. What mode of natural selection would lead to increased speciation?
    disruptive- this favors two phenotypes which could lead to them becoming separate species!
  43. Which mode of natural selection: The allele frequency shifts in one direction over time
  44. Which mode of natural selection: increases genetic variation when natural selection favors two extreme phenotypes
  45. Which mode of natural selection: it results in a decrease of genetic variation when natural selection selects against the phenotype
  46. Which mode of natural selection: the allele frequency stays the same
  47. Darwin's thought process for natural selection as the mechanism for evolution (4 bullet points)
    • 1.) all organisms have great capacity to reproduce
    • 2.) despite this, most populations maintain a stable size for long periods of time
    • 3.) because within a population, individuals in their traits, which influences the ability to reproduce
    • 4.) Those individuals with traits best suited to the environment will tend to produce more surviving offspring.
  48. Why is it so important for the offspring to be viable?
    so the traits can be passed down to other generations, so the lineage will not die
  49. Misconceptions of evolution (list 3)
    • evolution creates perfection- wrong, there are constraints with adaptation
    • evolution is over- wrong, evolution is still occuring
    • individuals limit their reproduction for the "good of the species"- wrong, adaptations come about via natural selection
  50. Hardy Weinberg principle/Equilibrium
    model that states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
  51. We are in Hardy Weinberg Equilibrium when there is... (5)
    • no gene flow
    • no genetic drift
    • no natural selection
    • no mutation
    • random matings
  52. What are the three species concept?
    • biological species concept
    • morphospecies species concept
    • phylogenetic species concept
  53. Biological species concept
    • defines a species as a group of populations that are reproductively compatible with each other
    • prezygotic barriers or postzygotic barriers
  54. Prezygotic barriers
    anything that prevents individuals from two populations/species forming a zygote together.
  55. Prezygotic barriers and their definitions (5)
    • temporal isolation- Populations adapted to different habitats or are active at different times of day or year.
    • habitat isolation- live in different places
    • behavioral isolation- Signals used toattract mates differ between populations.
    • mechanical isolation- can't physically mate
    • gametic isolation- gametes are not compatible
  56. Postzygotic barriers
    • Reduced hybrid viability (survivorship) or fertility (reproductive capacity).
    • ex. mule
  57. Why don't we always use the biological species concept? Issues?
    • some organisms reproduce asexually
    • it only applies to extant species (not extinct)
  58. Morphospecies concept
    classifies species based on their appearance
  59. Issues with the morphospecies concept:
    • two different species can look identical or very similar but they are different species
    • two same species can look completely different but they are the same species
  60. Phylogenetic Species Concept
    a group of organisms with a shared, unique genetic history
  61. Issues with Phylogenetic Species Concept
    • only available for a minority of species
    • polyploidy also violates this concept
  62. A tree falls over, separates two ants. The ants evolve into two different species. What type of speciation is this?
    Allopatric speciation by Vacariance (physical barrier)
  63. What are the two modes of speciation?
    • allopatric speciation (living apart)
    • sympatric speciation (living together)
  64. Allopatric speciation
    • species divergence through long-term spatial isolation, especially by a physical barrier (vicariance)
    • or by dispersal- some part of the population goes off and moves to a new geographic location and adapts
  65. Sympatric Speciation
    • speciation that occurs when two diverging populations live in the same area
    • 1.) by disruptive selection- adapt to different niches in the same geographic area
    • 2.) by polyploidization
  66. What is the difference between cladogenesis and anogenesis?
    • Anogenesis is over progression
    • Cladogenesis is branching off to form new species
  67. Adaptive Radiation
    • happens when one ancestral lineage diversifies rapidly, creating many species with diverse traits
    • rapid evolutionary diversification within a lineage
  68. Autopolyploidy – speciation involving failed meiosis and gamete fusion between 2 individuals of the same species
  69. Allopolyploidy – interspecific fertilization followed by chromosome doubling
  70. Define ecology
    the study of how organisms interact with the environment
  71. 2 components to “environment”:
    • Biotic – other organisms
    • Abiotic – physical environment
  72. Terrestrial Biomes (“communities”):
    characterized by dominant vegetation type; controlled by climate (annual mean temperature & precipitation)
  73. What determines temperatures?
    earth's curvature
  74. Why do we have seasons?
    earth's tilt at 23.5 degrees
  75. Precipitation:
    Hadley cells: major cycles in global air circulation
  76. Define rain shadow
    thirsty side of the mountain that lacks warm and moist air
  77. Population ecology
    srudy of how and why the number of individuals in a population change over time
  78. Density independent
    keeps growing
  79. Density dependent
    grows until it reaches carrying capacity
  80. Community ecology
    focuses on the interactions that affect the distribution or abundance of a species
  81. Types of species interaction and define them (5)
    • 1.) mutualism (+/+)- an interaction that benefits both species
    • 2.) competition (-/-)- an interaction that occurs when two species use a limiting resource
    • 3.) herbivory (+/-)- consumption of plant tissue
    • 4.) parasitism (+/-)- consumption of tissue/nutrients from host
    • 5.) predation (+/-)- one animal kills and consumes an individaul
  82. Competition is a result of....
    niche overlap
  83. Niche differentiation
    the evolutionary change in resource use
  84. Character displacement
    affects a trait to allow it to exploit different resources
  85. What happens if there is too much overlap between the niches of 2 different species? (state the term and define it)
    Competitive exclusion- the stronger species will drive the other species to extinction
  86. Macroevolution
    • Pattern of evolution over large time scales
    • Larger than the species level
    • Same 4 mechanisms of gene flow, natural selection etc
  87. Earth's estimate age
    4.54 billion years
  88. Precambrian Era and it's 3 key events
    • first 4 billion years in Earth
    • oxygen revolution
    • Cambrian explosion- first appearance of oldest animal fossils
    • first eukaryotes- membrane bound organelles, nucleus
  89. Paleozoic Era key events
    • plants colonize land
    • continental drift- movement of continents over time
  90. How might the building of mountain ranges affect organisms with respect to evolution and its mechanisms?
    rain shadows effects and reduce gene flow between populations
  91. Mass extinction
    • a large scale, widespread extinction event that occurs within 1 million years
    • rapid extinction
  92. Background extinction
    normal rate of extinction
  93. Early Paleozoic Era
    • Cambrian explosion- huge amount of animal diversity
    • first mass extinction due to the cooling at the end of Ordovican
  94. Mid-Late Paleozoic Era
    • great diversification of land plants; insects and tetrapods evolved and diversified (including ancestors of mammals …)
    • Cooling at end Devonian – Second great mass extinction
  95. Late Paleozoic Era
    • formation of Pangea
    • warm and humid on land- great forests (coal)
    • End Permian (P/T) extinction- due to volcano, 95% marine species, 70% terrestrial families
  96. The Mesozoic Era
    • Mostly hot, humid
    • Radiation of reptiles, origin and radiation of dinosaurs
    • Radiation of gymnosperms
    • origin of flowering plants (angiosperms), birds, mammals
  97. Two Mesozoic Mass Extinctions
    • 1) End Triassic (200 mya)
    • 2) K/T or K/P (65 mya- end of dinos) Iridium anomaly at boundary
  98. The Cenozoic Era (65 mya to present)
    • Cooler and drier
    • Slow recovery at first
    • Radiation of birds, mammals, angiosperms, insects
    • Origin of apes (30 mya)
  99. True or False: “Prokaryotes are a paraphyletic group”
  100. Paraphyletic group
    evolutionary group that includes an ancestral population and some but not all of its descendants
  101. Monophyletic group
    evolutionary group that includes an ancestral population and all of its descendants
  102. Prokaryotes are (3)
    • Ubiquitous- found everywhere
    • Abundant
    • Diverse
  103. Phototrophs
    light energy
  104. Chemoorganotrophs
    • organic molecules
    • ex. glucose
  105. Chemolithotrophs
    • inorganic molecules
    • ex. NH3, H2S
  106. Autotrophs
    • use inorganic sources
    • ex. CH4 , CO2
  107. Heterotrophs
    absorb carbon compounds produced by other organisms
  108. Lateral gene transfer
    bacteria can acquire genes from each other and from the environment
  109. Bioremediation
    use of living organisms to degrade pollutants
Card Set
Bio 94
Midterm 1