23_Biol221_04_14_2-11

This works out to about 16 mutalons per sperm cell in

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Unformatted text preview: einberg Equilibrium 3. Popula=on size is very large. Small populaLons are suscepLble to geneLc drid and founder effects 44 Requirements for Hardy Weinberg Equilibrium 4. Migra=on in or out is negligible. MigraLon (or gene flow): Some beetles with brown genes immigrated from another populaLon, or some beetles carrying green genes emigrated. 45 Requirements for Hardy Weinberg Equilibrium 4. Migra=on in or out is negligible. MigraLon (or gene flow): Some beetles with brown genes immigrated from another populaLon, or some beetles carrying green genes emigrated. EmigraLon and ImmigraLon has more affect on allele frequencies in small populaLons. 46 Requirements for Hardy Weinberg Equilibrium 5. Muta=on does not occur. MutaLon: Some “green genes” randomly mutated to “brown genes” (although since any parLcular mutaLon is rare, this process alone cannot account for a big change in allele frequency over one generaLon). 47 New MutaLons Arise in the “Separate” PopulaLons From tables 4 and 5 in "Rates of Spontaneous MutaLon", by JW Drake et al, GeneLcs 148:1667 ­1686 (April, 1998): Organism Effec=ve genome size (Ge) bacteriophage M13 6.4 × 103 bacteriophage lambda 4.9 × 104 bacteriophages T2 & T4 1.7 × 105 E. coli 4.6 × 106 Saccharomyces cerevisiae 1.2 × 107 Neurospora crassa 4.2 × 107 C. elegans 1.8 × 107 Drosophila 1.6 × 107 Mouse 8.0 × 107 Human 8.0 × 107 Muta=ons per genome/per replica=on 0.0046 0.0038 0.0040 0.0025 0.0027 0.0030 0.004 0.005 0.014 0.004 Note that for humans, the number of cell divisions prior to sperm formaLon in a male of age 30 is about 400. This works out to about 1.6 mutaLons per sperm cell. In the 28 January 1999 issue of Nature, in the arLcle "High genomic deleterious mutaLon rates in hominids" Walker and Kneightey esLmate that the mutaLon rate in the effecLve genome is a bit higher, 4.2 muta=ons per individual. 48 SelecLons Act Upon New MutaLons • MutaLons happen. • They happen with great regularity. • Almost all mutaLons are neutral. • Of the remainder, benefit/harm depends on circumstances 49 How Does SelecLon Act Upon New MutaLons 50 How Does SelecLon Act Upon New MutaLons Birds eat the kind of moth they can see the best. In England before the Industrial RevoluLon trees are oden covered with light colored lichens. As a result light moths were favored because they were hard to see on the bark of trees whereas the dark moths were easy to see; birds ate the dark moths. During the worst years of the...
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This note was uploaded on 01/20/2014 for the course BIOL 221 taught by Professor Gallagher,kimberly during the Spring '13 term at UPenn.

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