Pt. 2 Bio Final

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Pt. 2 Bio Final
2011-02-24 14:58:06

bio final exam
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  1. speciation
    the process by which one species splits into two or more species; responsible for diversity of life
  2. microevolution
    changes over time in allele frequencies in a population
  3. macroevolution
    the broad pattern of evolution over long time spans
  4. biological species concept
    defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance; appearance is helpful in identifying species, but it doesn't define species; species are identified by the ABSENCE of gene flow
  5. reproductive isolation
    prevents the formation of new species because of the existence of biological factors (barriers) that impeded members of two species from producing viable, fertile offspring; block gene flow between species and the formation of hybrids
  6. prezygotic barriers
    block fertilization from occurring; (1) impede members of different species from attempting to mate (2) preventing an attempted mating from being completed successfully (3) hindering fertilization if mating is completed successfully
  7. postzygotic barriers
    contribute to reproductive isolation once the zygote is formed; ex: developmental errors may reduce survival/problems after birth leave offspring infertile or unable to survive long enough to reproduce
  8. habitat isolation
    2 species that occupy different habitats wihtin the same area may see each other rarely even if they aren't separated by geographic barriers; pre
  9. temporal isolation
    species that breed during different times of day, seasons, or years can't mix gametes; pre
  10. behavioral isolation
    courtship rituals that attract mates and other behaviors unique to a species are reproductive barriers; such rituals allow for mate recognition (a way to identify potential mates of the same species); pre
  11. mechanical isolation
    mating is attempted, but morphological differences prevent its successful completion; pre
  12. gametic isolation
    sperm of one species may not be able to fertilize the eggs of another species (ex: it cannot survive in reproductive tract of female); pre
  13. reduced hybrid viability
    the genes of different parent species may interact in ways that impair the hybrid's development or survival in its environment; post
  14. reduced hybrid fertility
    when hybrids are sterile; meiosis can fail to produce normal gametes if the two parent species differ in chromosome number or structure; post
  15. hybrid breakdown
    when 1st generation hybrids are fertile and stable, but their offspring with either one another or a parent are feeble or sterile (steeble); post
  16. morphological species concept
    characterizes a species by body shape and other structural features; can be applied to both asexual and sexual organisms
  17. ecological species concept
    views a species in terms of its ecological niche
  18. phylogenetic species concept
    defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life
  19. allopatric speciation
    gene flow is interrupted when a population is divided into geographically isolated subpopulations
  20. sympatric speciation
    speciation occurs in populations that live in the same geographic area; less common than allopatric; can occur if gene flow is reduced by factors such as polyploidy, habitat differentiation, and sexual selection
  21. autopolyploid
    an individual that has more than two chromosome sets that are all derived from a single species
  22. allopolyploid
    an organism that has two sets of chromosomes, each from one parent; are usually only fertile when reproduction is asexual
  23. hybrid zone
    a region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
  24. reinforcement
    when natural selection strengthens prezygotic barriers because hybrids are less fit than members of their parent species; formation of hybrids is reduced; because of this, barriers of reproduction between species should be stronger for sympatric species than for allopatric species
  25. punctuated equilibria
    periods of apparent stasis punctuated by sudden change
  26. phylogony
    the evolutionary history of a species or group of species
  27. systematics
    a discipline focused on classifying organisms and determining their evolutionary relationships; used to construct phylogenies
  28. binomial
    the first part of the binomial naming system is the genus and is where the species belongs; the second part is called the specific epithet and is unique for each species within the genus
  29. taxon
    the named taxonomic unit at any level of the hierarchy
  30. phylogenetic tree
    the evolutionary history of a group of organisms can be represented in a branching diagram
  31. PhyloCode
    a classification based entirely on evolutionary relationships; it only names groups that include a common ancestor and all of its descendants
  32. sister taxa
    groups of organisms that share an immediate common ancestor and are therefore each other's closest relatives
  33. a tree that is rooted...
    means that a branch point within the tree represents the last common ancestor of all taxa in the tree
  34. polytomy
    a branch point from which more than two decendant groups emerge; indicates that evolutionary relationships among the descendant taxa are not yet clear
  35. analogy
    a similarity due to convergent evolution; a bat wing is ANALOGOUS to a bird's wing
  36. homoplasies
    analogous structures that arose independently (from the Greek "to mold in the same way")
  37. molecular homoplasies
    shared nucleotide bases in organisms that are otherwise very different; coincidental matches
  38. molecular systematics
    uses DNA and other molecular data to determine evolutionary relationships
  39. cladistics
    biologists place species into groups called clades, each of which includes an ancestral species and all of its decendents
  40. monophyletic
    a taxon (group of organisms) which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group
  41. paraphyletic
    a group which consists of an ancestral species and some, but not all, of its decendents
  42. polyphyletic
    includes taxa with different ancestors
  43. shared ancestral character
    a character that originated in an ancestor of the taxon; (ex: in mammals, the backbone)
  44. shared derived character
    an evolutionary novelty unique to a particular clade (ex: in mammals, hair)
  45. outgroup
    a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the species we are studying (ingroup)
  46. maximum parsimony (Occam's Razor)
    it is important to first investigate the simplest explanation that is consistent with the facts
  47. maximum likelihood
    given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events
  48. phylogenetic bracketing
    we can predict (using parsimony) that features shared by two groups of closely related organisms are present in their common ancestor and all of its descendants
  49. orthologous genes
    homologous genes that are found in different species because of speciation; widespread and can extend over huge evolutionary distances
  50. paralogous genes
    result from gene duplication, so they are found in more than one copy in the same genome
  51. molecular clock
    a yardstick for measuring the absolute time of evolutionary change baseed on the observation that some genes and other regions of genomes appear to evolve at constant rates
  52. neutral theory
    much of evolutionary change in genes and proteins ahs no effect on fitness and therefore is not influenced by Darwinian selection
  53. horizontal gene transfer
    the movement of genes between organisms in different domains; the process in which genes are transfered form one genome to another through mechanisms such as exchange of transposable elements and plasmids, viral infection, and PERHAPS fusion of organisms