22-24 - 9/22 Allele frequency: Genotype frequency: can...

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9/22 Allele frequency: Genotype frequency: can figure out what allele freq of gene pool is determined from genotype of parents= same if HWE Except: mutation; -allele freq of zygotes if HWE: same as gene pool -genotype freq AA=p^2, Aa=2pq, aa=q^2 --if mutation: AA=p’^2, Aa=2p’q’, AA=p’^2 allele freq of new adults: -if HWE=same as zygotes genotype freqs: -if HWE=same as zygotes EXCEPT: -selection: AA=p^2w Aa , Aa=2pqw Aa aa=q^2 w Aa -w= relative fitness AA= 1 1 1-t --- 1 Aa= 1-s 1-s 1 ---1-hs Aa= 1-s 1-2s 1-s ---1-s -gene flow: the incorporation of genes into a gene pool of one pop from one or more other pops, NOT MIGRATION (migration is movement of entire population from one place to another) - population 1 and population 2 have differing allele freqs. But then migration occurs. m= measure ofgene flow=proportion of migrants that contribute to the next generation - with gene flow: p1’=(1-m)p1 +mp2 p2’=(1-m)p2 +mp1 p1’-p1=deltap1=m(p1-p2) p2’-p+deltap2=m(p2-p1) --simple weighted averages; evolution will occur if gene freqs change --effects of gene flow: -decreases genetic variability among populations. At equilibrium, deltap=, 0 when p1=p2, homogenizing force -increases genetic variability within population Selection vs gene flow: -gene flow can constrain or promote adaptation -it can prevent local adaptation -it can introduce new adaptive mutations Heavy metal tolerance in plants: -toxic soils b/c of mines -rapid evolution of tolerance, but tolerance outside of the mine area is bad for not
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heavy metal environment -graph: the adult population sample has higher tolerance than seed population in mine area, so higher selection for plants w/ tolerance. Then going downwind, the seeds that were produced in mine area but moved downwind-> farther away, the adult population has a lower tolerance than seeds b/c plants are selected against tolerance in non-heavy metal areas. If no gene flow, then adult and seed population samples would be in same ration as non-mine populations upwind of mine. -theory provides some rules of thumb:
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This note was uploaded on 02/19/2010 for the course BIO 370 taught by Professor Edwards during the Spring '08 term at University of Texas at Austin.

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22-24 - 9/22 Allele frequency: Genotype frequency: can...

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