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xijunzhu
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which scientists argued for continuous distribution of traits
darwin, f. galton, K. pearson
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dominant trait what is the genotype and phenotype ratios
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Lamarckism
organism can pass on characteristics that it acquired during its lifetime to its offspring.
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saltation
sudden change from one generation to the next
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mutation is good or bad
bad
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thomas malthus
survival is the perpetual struggle for food and room
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Darwin went to what school
Dr. Butler's school, strictly classical
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Henslow
almost took Darwin's position on the Beagle
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when was the voyage of the Beagle
Dec 1831-Oct 1836
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charles lyell
darwin's advisor
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alfred russel wallace
came to same conclusions as Darwin on the origin of species
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what was the problem of blending inheritance?
natural selection would not work if the extremes are eliminated...need a particular form of inheritance that does not lose extremes
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who advocated the cell theory of 1839
weismann, johannsen, morgan
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RA fisher
est. population genetics
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what is population genetics
study of distribution and changes in allele frequency in a population as it is subject to selection, genetic drift, mutation and genetic recombination
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what was the reconciliation between the mendelians and the biometricians
polygenics: phenotype is influenced by more than one gene
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what are the assumptions of hardy-weinberg relation?
- random pairing, no assortative mating
- no selection
- no migration
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why is H-W an equilibrium?
the new frequency is the same as the old frequency
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what does HW ensure?
- maintenance of genetic variation
- translation between allele and genotype frequencies
- provides evidence of evolutionary action when genotype frequencies deviate
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how does variation occur?
through mutation and recombination (reshuffles mutations in new configurations)
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can mutation drive evolution?
too infrequent, cannot itself drive evolution
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how is the fate of variation determined?
by both stochastic (genetic drift, random) and deterministic (natural selection). The latter leads to adaptation.
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natural selections acts on who, what are its consequences?
acts on individuals, but consequences are populational
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sources of genetic variation?
- non-disjunction (meiotic anomalies)
- mutations: DNA rep errors
- recombinations (mutations shuffled into new configurations)
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how to measure genetic variation?
- mendelizing morphological or serological traits
- chromosomal variation
- protein variants
- restriction mapping
- DNA sequence
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what is the paradox at heart of darwinism
mutations are bad for individuals but required for evolution
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robins laying eggs is what kind of selection?
stabilizing
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peppered moth vs. dark moths what kind of selection?
directional
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polymorphism
two alleles at 1 locus
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what percentage of human genome encodes proteins?
1.2%
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what percent of human genes are in the mouse
99%
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are we more homologous to fruit fly or nematode worm?
- fruit fly (61% of homologous proteins) vs 43%
- half a billion years of evolutionary separation from humans
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how to do functional tests of similarity?
- eyeless drosophila is the homolog of pax-6 in mammals
- inject rat gene for eye, drosophila grows eye
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birth weight is what kind of selection?
- stabilizing
- increase in frequency of the intermediate phenotype
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synonymous evolution, which is faster?
- silent mutations
- synonymous mutation is faster than non synonymous
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who performed experiments on peppered moth?
kettlewell
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acclimate
DNA doesn't change
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convergent evolution
- independent evolution of similar features in species of different lineages.
- creates analogous structures with similar form or function, but not present in last common ancestor of those groups
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who did experiments with blind cavefish (astyanax mexicanus)
borowsky
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after the drought, what kind of beaks were the best?
bigger beaks, because the size and hardness of the seeds increased.
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achromatopsia
- can't see color
- affected 5% of population in micronesia, ping clap
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rate of change of gene frequency by random drift depends on what?
size of the population
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who did research on the lynx and the hare
e t seton
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effective population size
- when drift has no significant effect; population has the same magnitude of genetic drift as the actual population
- in fluctuating populations, N is the harmonic mean of the population size
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Markov proces
random walk whose transition is dependent only on its position in the previous step
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absorbing barriers
in absence of selection gene frequencies vary until population is fixed (0 or 1 for an allele)
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who came up with neutral theory of evolution, when?
motoo kimura 1968
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what does kimura propose?
- most mutations are neutral
- immediately goes to zero frequency if the mutation is neg
- rarely positive (goes to fixation)
- so population size does not matter
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what does the total extent of genetic divergence depend on?
time since isolation
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