Evolution Review

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Evolution Review
2010-02-21 00:21:11

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  1. biological evolution
    change in the properties of groups of organisms over generations
  2. natural selection
    • differential survival and reproduction (fitness) of individuals based on genetic differences in some trait
    • leads to adaptation
    • offspring resemble parents
    • more offspring produced each generation
  3. adaptation
    • characteristic that enchances likelihood of reproduction and survival
    • becoming better suited for their environment
  4. scientific vs nonscientific definitions of
    • theory: hunch or speculation, explanation that is broad in scope that generates a new, testable, hypothesis and is supported by a lot of data
    • evolution: coming from apes, due to natural selection, migration, mutations
    • adaptation: changing due to environment, changes to enchance reproduction and survival
    • fitness: being in good shape, how well you can reproduce in order to pass on genoic makeup
  5. why teach evolution
    • predicits biological complexity and diversity
    • influences all aspects of biology
    • apply to real life issues
    • there is a large amount of data that all points to evolution
  6. Aristotle
    Nicolas Steno
    Carolus Linnaeus
    Jean-Baptiste Lamarck
    Count Buffon
    Georges Cuvier
    Charles Lyell
    Aristotle: species will always be the same, 384-322 BCNicolas Steno: father of palentology, proposed rock formation and fossils are related, 1666Carolus Linnaeus: taxonomy, species unchanging (ideal structure and function), 1735Jean-Baptiste Lamarck: speices change over time (giraffs), inheritance of acquired characteristics, simple to complex forms, 1744-1829Count Buffon: speices change over time, different parts of world with similar climate have different species, climate change caused worldwide spread of species from orgin, proposed common ancestryGeorges Cuvier: founded paleontology (compared living animals with fossils), extinction, catastrophismCharles Lyell: uniformitarianism (geological features fromed by slow moving forces)Mathus: principle of population growth (exponential if resources were unlimited), struggle for existance
  7. mechanisms for evolution propopsed by lamarck and dawin
    • lamarck: species passed on what they inherited during their lifetime (ex. if you had a child in summer while you were tan, the child would be tan)
    • darwin: all species related and decended from common ancestor, species evolve over time due to adaptation and natural selection,
  8. lyell and malthus contributions to darwins hypothesis of evolution by natural selection
    • lyell: slow moving changes, length of geologic time, uniformitarianism
    • mathus: struggle for existance, those who are better fitted (adaptations from natural selection) will survive the conditions and reproduce
  9. evidence for Darwins natural selection hypothesis
    • fossil animals shared characteristics of modern organisms (organisms change over time)
    • biogeography- saw similiar species in similar environments (species change over time to be suited to environment)
    • common animals in same area (all were descended from single species from a mainland)
  10. modern synthesis
    • population processes (mutation, recombination, natural selection) account for orgin of species
    • molecular evolutionary biology (phylogenetic trees)
  11. bacteria fight back
    • S. aureus began to acquire genes that confer resistance to other common antibiotics, carried on the same mobile
    • cassettes as mecA. The result was a bug that was both far more difficult to treat and, “pretty adaptive to surviving in hospitals.” multidrug-resistant MRSA.
  12. structure of DNA and how mutation affects protein sequence, structure and function
    • DNA has a phosphate group, nitrogenous base (pyrimidine or purine)
    • mutation causes mismatches of pairs which causes a different rna code to be signaled. AA sequence affects how a protein folds and the folding determines function
    • changes in genotype may lead to changes in phenotype
  13. Central Dogma

    DNA turned into mRNA which can relay the information and can call for the correct protein sequence
  14. ultimate source of genetic variation
    • mutation
    • a mismatched base pair causes new protein which may or may not evolve a species
  15. types of mutations
    • substitution (transition/transversion)
    • frameshift (deletion/insertion)
    • inversion
    • reciprocal translocation
  16. mutation rate and natural selection
    • a high mutation rate could cause better fitness in a changing environment
    • mutation usually not good (deleterious)
  17. why mutation is random
    Mutations do not occur due to need.

    ex. exposure to harmful chemicals may increase the mutation rate, but will not cause more mutations that make the organism resistant to those chemicals. In this respect, mutations are random—whether a particular mutation happens or not is generally unrelated to how useful that mutation would be.
  18. gene pool
    total of all the alleles of a gene that occur in a population
  19. locus
    gene flow
    • locus: location of gene or sequence on a chromosome
    • allele: alternative DNA sequences at the same physical locus, which may or may not result in different phenotypic traits
    • haplotype: combination of alleles at multiple loci that are transmitted together on the same chromosome
    • gene flow: the transfer of alleles of genes from one population to another.
  20. Hardy Weinberg
    • conditions in which a population will not evolve
    • large popluations with random mating, allele frequencies will remain constant
  21. conditions in which gene frequencies change
    • mutation: creates new alleles
    • migration: introduces new alleles from different popluations
    • natural selection: certain genotypes produce more offspring
    • genetric drift: change due to chance
    • non random mating: mating combines alleles into genotypes
  22. Hardy weinberg equations
    • allele: p + q = 1
    • genotype: p2 + 2pq + q2 = 1
  23. importance of variation
    ability for population to survive disease, allows for more mutations,
  24. 3 patters of population distribution
    • sympatric: populations overlap in distribution (same place, no breeding)
    • parapatric: next to eachother (ex. divergence to feeding on different things)
    • allopatric: isolated distributions (migration)
  25. scenario of genetic drift
    • a bunch of flowers on a hill, by change, pink are near the top, white flowers near the bottom.
    • flood comes through, washes away white flowers
    • new allele frequency with majority of flowers pink
  26. scenario of natural selection
    due to unknown bug, all fruits no longer grow in a niche. the birds in this niche now need to feed on insects that live inside the trees. the birds with narrow, longer beaks will survive better than those with fat, short beaks. therefore the narrow beaks will reporduce more.
  27. experimental demonstration of natural selection
    • fish with 2 distinct colors
    • predators are introduced in the ecosystem that favor the bright colored fish
    • since the bright colored fish are being eaten, the drab fish have higher fitness and reproduce
    • conrol: normal ecosystem with out predators (has both colored fish0
  28. adaptation
    • adaptation: due to natrual selection, occurs due to selective pressure
    • preadatpation: already having a trait before using it (ex. dinosaurs having feathers for insulation before flying)
    • exaptation: change in function due to evolution?
  29. natural selection does/doesnt
    does: increases a trait, differences in reproductive success

    doesnt: perfection (cant act on mutations that havent occured, tradeoff, developmental constraint), serve as a model of ethics or morality
  30. argue "natural selection is random"
    • its not because:
    • those who survive are the ones who will mate
    • genetic variants that aid survival and reproduction are much more likely to become common than variants that don't

    is because mutations are random
  31. phenotypic plasticity
    • genotype producing multipe phenotypes dependin on the environment
    • ex. caterpillars: morphology changes due to environment (fuzzy or bristle looking)
  32. why cant individuals evovle
    because in order to evolve, you need to have a change in genes over time. An individual is born with a set of genes that do not change.
  33. why cant a population be the unit of natural selection
    because within a population, each individual does not have the exact same alleles. So since one individual will be a little better than the rest, that individual will reproduce more.
  34. genetic drift and natrual selection
    • founder: seperating into smaller groups, not all alleles will be present in the same frequencies
    • bottle neck: only a few individuals contribute genes to form a new population

    changing allele frequencies causes natural selection to have a limited allelic advatage.
  35. migration within and between populations
    • within: causes variation to increase since new alleles are introduced
    • between: causes variation to decrease since each population is becoming more like the other
  36. adaptive vs nonadaptive evolutionary change
    adaptive: natural selection

    nonadaptive: phenotypic plasticity. turning on genes due to different environment (ex barnacles penis size), migration, genetic drift
  37. migration
    gene flow
    genetric drift
    migration: movement of alleles between populationsgene flow: the transfer of alleles from the gene pool of one population to the gene pool of anothergenetric drift: chance or random influence on evolutioncoalescence: a sample of individuals from a population to trace all alleles of a gene shared by all members of the population to a single ancestral copy
  38. rate of drift due to population size, migration, and selection
    • larger populations are less affected by drift
    • migration reduces effects of migration
    • selection increases genetic drifts effects
  39. modes of natural selection
    • directional: homozygote advantage, over time favored allel frequency will equal 1 (fixed), reduces diversity, disadvantageous allel lost over time
    • stabolizing: favors intermediate varients and acts against extreme phenotypes, heterozygote advantage, balencing selection (keeping both in population)
    • diversifying: selects agains phenotypes near the average value. favoring extreme phenotypes, can lead to speciation, diffictult to get populations to diverge
  40. rate of natural selection
    • strong selection causes frequencies to change fast
    • ex. trees covered with soot, white moths turn black. trees get clean, black moths turn back white. all within 40 years.
  41. why variation is good
    • in case of epidemic, climate change, or natural causes, variation is good to keep the species alive. if all are the same, one problem can wipe out entire species.
    • -mechanisms for maintenance of allele polymorphism??
  42. frequency of allele affecting fitness
    inverse frequency dependent selection: rare is good

    positivefrequency dependent selection: common is good