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Unformatted text preview: STABALIZING SELECTION o SELECTION FOR THE MIDDLE FITNESS, ELIMINATES EXTREMES o Favors heterozygote AA= p= 1-S Aa=2pq=1 aa=q=1-t P = p(1-S) + 2pq * (1) / p(1-S) + 2pq + q(1-t) o Bottom = p - pS + 2pq + q qt and p+2pq+q=1 o SO p = p(1-s)+pq/ 1-ps-qt dP = p-p o (p(1-S)+pq/1-ps-qt) - P o multiply p by denominator o add both neumerators (bottom will be total) o Cancel out the p+2pq+q because it equals one o Factor out the Ps o Youll get 1-p which will equal q o So you will get pqs+pqt/total Which will equal pq(qt-ps)/total for the change in p The graph of p in a pure heterozygote world would remain constant over time o If p = then dP = 0 o If p is large then dP = negative Consequence of stabilizing selection for heterozygotes, the fitness of p will eather lower or increase in...
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- Winter '11