{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lec_5_cond_13

Feck 18 offspringlifetime w ccr5 ccr5 surfeck 14

Info iconThis preview shows pages 4–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Sur.*Fec.*K = 1.8 offspring/lifetime W* CCR5/ CCR5 = Sur.*Fec.*K = 1.4 offspring/lifetime Gene pool p =freq(A1) q =freq(A2) Genotype pool P = prop(A1A1) H = prop(A1A2) Q = prop(A2A2) Gen=0 Gene pool p ! =freq(A1) q ! =freq(A2) Gen=1 Natural selection is on phenotypes produced by the genotypes W 1 , W 2 , W Gene Pool Gen=0 Selection Gen= 1 W 1 freq (A 2 ) = q W 2 qW 2 W W 1 Gene Pool W total ʼ = W W = 1 Gene Pool q ʼ = qW 2 W p W 1 = 1- p ʼ p ʼ = p W 1 freq (A 1 ) = p (Total) = p +q = 1 Next, let p = proportion of ! CCR5
Background image of page 4

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
W = p (W 1 ) + q (W 2 ) = .1 (.91) + .9 (.72) = 0.739 W 2 = q (W 22 ) + p (W 12 ) = .9 (.7) + .1 (.9) = 0.72 W 1 = p (W 11 ) + q (W 12 ) = .1 (1) + .9 (.9) = 0.91 Because humans have such a long generation time, substantial evolutionary adaptation to the HIV/AIDS will take at least about 2500 years (a hundred generations) But eventually it would occur Let, Δ CCR5 = A1 CCR5 = A2 p = 0.1 q = 0.9 (rounding 9.1% to 10%) Then, to make math easier p ’ = p in next generation = p W 1 W = 0.1 .91 .739 = .123 = p ’ - p = .123 - .1 = 0.023 So the change is SUBSTANTIAL but SLOW Δ p = Change in p If evolution is so slow, then how did Δ CCR5 rise to a frequency of 9% in Northern Europe? Recent evidence indicates that another virus also uses the CCR5 receptor to enter cells the virus that causes smallpox, so 100’s of years of past adaptation to smallpox may have lead to the high frequency of Δ CCR5 in N. Europeans. We do not yet know for certain, but Very Important to do study questions from this lecture material p = 0.1 p ’ = .123 24 0.05 0.15 0.25 0.1 0.2 0.3 Generation 0 1 2 3 4 5 W is the average fitness of an allele in the gene pool and it also is the average fitness of an individual in the population = average population fitness Frequency of Δ CCR5 ( p ) 4 years with 2-week life cycle But only W CCR5/ Δ CCR5 = W 12 = W* 12 / W* MAX = 1.8/2 = 0.9 W Δ CCR5/ Δ CCR5 = W 11 = W* 11 / W* MAX = 2/2 = 1.0 W CCR5/CCR5 = W 22 = W* 22 / W* MAX = 1.4/2 = 0.7 0.1 0.5 1.0 100 0 (2500 years)
Background image of page 5
population one individual W = individual fitness = Darwinian fitness average W for all A 1 A 1 average W for all A 2 A 2 average W for all A 1 A 2 W * 11 W * 12 W * 22 divide by largest W * ij W 11 W 12 W 22 relative
Background image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}