Pt. 1 Bio Final

  1. evolution
    descent with modification; change in the genetic composition of a population from generation to generation
  2. Aristotle and Evolution
    viewed species as unchanging; thought that life-forms could be arranged on a ladder of increasing complexity = SCALA NATURAE
  3. Linnaeus
    developed the binomial (two-part) system of naming species; was a nested system of classification grouping similar species into increasingly general categories
  4. fossils
    remains/traces of organisms form the past; most are found in sedimentary rocks formed from sand and mud that settled to the bottom of bodies of water
  5. catastrophism
    the idea that past events occurred suddenly and were caused by mechanisms DIFFERENT from those operating in the present; advocated by Cuvier, who speculated that each boundary between strata indicated the occurence of a catastrophe
  6. uniformitarianism
    idea that mechanisms of change are constant over time; Lyell (using Hutton) speculated that the same geological processes are operating today as in the past AND at the same rate
  7. Lamarck
    found lines of decent and explained them using use and disuse (parts of the body that are used become larger/stronger while those that go unused deteriorate) AND inheritence of acquired characteristcs (an organism could pass these modifications to its offspring)
  8. adaptations
    chaaceristics of organisms that enhance their survival and reproduction in specific environments
  9. natural selection
    individuals with certain inherited traits leave more offspring that individuals with other traits; a process of editing rather than a creative mechanism; doesn't create but SELECTS for individuals already present in a population
  10. Darwin developed two ideas in his book:
    • 1) descent with modification explains life's unity & diversity
    • 2) natural selection brings about the match between organisms and their environment
  11. artificial selection
    when humans modify other species over many generations by selecting and breeding individuals that possess desired traits; such organisms often bear little resemblance to their wild ancestors
  12. cetaceans
    mammalian order that includes whales, dolphins and porpoises
  13. homology
    similarities between species with characteristics that have underlying similarities even thought they might have very different functions; a result of common ancestry
  14. homologous structures
    variations on a structural theme that was present in their common ancestor; ex: anatomical resemblances in the skeletons of arms, forelegs and flippers of mammals
  15. vestigal structures
    remnants of features that served important functions in the organism's ancestors
  16. evolutionary tree
    a diagram that reflects evolutionary relationships among groups of organisms
  17. convergent evolution
    the independent evolution of similar features in different lineages; responsible for analagies
  18. analogous
    features in different species' that have adapted to similar environments in similar ways; resemblances due to species sharing features because of convergent evolution
  19. biogeography
    the geographic distribution of species; influenced - among other things - by continental drift
  20. continental drift
    the slow movement of Earth's continents over time; about 250 million years ago these movements created Pangea
  21. endemic
    species that are found in only one place in the world; islands generally have many endemic species; most island species are closely related to species form the nearest mainland or a neighboring island
  22. microevolution
    the change in allele frequencies in a population over generations; evolution on its smallest scale; caused by (3) natural selection, genetic drift, AND gene flow
  23. discrete characters
    characters that can be described in an either-or-basis; ex: purple or white flowers in pea plants; determined by a SINGLE gene locus with different alleles that produce distinct phenotypes
  24. quantitative characters
    results from the influence of two or more genes on a single phenotypic character; resposible for most heritable variation; vary along a continuum within a population
  25. average heterozygosity
    the average percent of loci that are heterozygous; estimated by looking at protein products of genes using electrophoresis; used to quantify gene variability (at the whole-gene level)
  26. nucleotide variability is measured...
    by comparing the DNA squences of two individuals in a population and then averaging the data from many such comparisons
  27. geographic variation
    differences in the genetic composition of seperate populations; ex: a cline, or graded change in a character along a geographic axis
  28. mutation
    a change in the nuleotide sequence of an organism's DNA; ultimate source of new alleles
  29. RNA genome
    what HIV has; it has a much higher mutation rate than DNA genome because of the lack of RNA repair mechanisms in host cells
  30. population
    a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring
  31. gene pool
    all of the alleles for all the loci in all individuals of the population; a way to characterize a population's genetic makeup
  32. hardy-weinberg equilibrium
    a gene pool where the frequencies of alleles and genotypes in a population remain constant from one generation to the next provided that ONLY Mendelian segregation and recombination of alleles are at work
  33. conditions for hardy-weinberg:
    • 3 NO's!
    • (1) no mutations (2) no natural selection (3) no gene flow
    • 2 YES's!
    • (1) random mating (2) large population size
  34. adaptive evolution
    evolution that results in a better match between organisms and their environment; caused by natural selection when it consistantly favors some alleles over others
  35. genetic drift
    chance events that cause allele frequencies to fluctuate unpredictably from one generation to the next, especially in small populations
  36. founder effect
    when a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool differs from the source population
  37. bottleneck effect
    development of a new species caused by a severe drop in population size; by chance certain alleles may be over or underrepresented or event absent meaning there'll be low levels of genetic variation after
  38. genetic drift summary
    (1) significant in small populations (2) causes allele frequencies to change at random (3) can lead to a loss of genetic variation within populations (4) can cause harmful alleles to become fixed
  39. gene flow
    the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes; tends to reduce genetic differences between populations
  40. relative fitness
    the contribution an individual makes to the gene pool of the next generation RELATIVE to the contributions of other individuals
  41. directional selection
    occurs when conditions favor individuals exhibiting one extreme of a phenotypic range thereby shifting the frequency curve for the phenotypic character in one direction or the other; common when a population's environment changes or when members move to a different habitat
  42. disruptive selection
    occurs when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes
  43. stabilizing selection
    acts against both extreme phenotypes and favors internediate variants; reduces variation; maintains status quo for a specific phenotypic character (ex: human baby birth weights)
  44. sexual selection
    a form of natural selection in which individuals with certain inherited characteristics are more likely than other individials to obtain mates
  45. sexual dimorphism
    marked differences between the two sexes in secondary sexual characteristics that AREN'T directly associated with reproduction or survival
  46. intrasexual selection
    selection within the same sex, individuals of one sex compete directly for mates of the opposite sex; occurs among males (ex: peacocks)
  47. intersexual selection
    individuals of one sex (usually females) are choosy in selecting their mates from the other sex; often times depends on the showiness of the males's appearance; also called mate choice
  48. balancing selection
    occurs when natural selection maintains two or more forms in a population; inclues heterozygote advantage & frequency-dependent selection
  49. heterozygote advantage
    occurs when organisms who are heterozygous at a particular locus have greater fitness than do both kinds of homozygotes (ex: fucking sick-cell anemia)
  50. frequency-dependent selection
    when the fitness of a phenotype declines if it becomes too common in the population (ex: scale eating fish, left side/right side)
  51. neutral variation
    when nucleotide differences in noncoding sequences appear to confer no selective advantage or disadvantage
Card Set
Pt. 1 Bio Final
final exam review