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Lecture 12

Lecture 12

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McMaster University
Life Sciences
Brett Beston

Lecture 12Tuesday November 29 2011730 PMRunway sexual selectionFemales select for males with good genesSometimes females also choose for less important genes like song complexity and peacock tails which decrease their survivalDifficulty extreme mail traits seem to reduce male survivalExplanation such traits increase male reproductive successThe medium tail is widely spread because high survival natural and sexual selectionModels of runaway sexual selectionAssume that there are 2 gene loci in allindividuals males and females1Gene 1 codes for a certain male trait for example bright color2Gene 2 codes for preference towards bright male colorAll individuals have these loci but there is heritable individual variationC color gene Ppreference geneCPCPCPCThe frequency of the colorful male increases relative to the males without the geneThe females choose the male with extreme version of gene P therefore they have gene P alsoIn this process there is no negative feedbackMeaning the long tail males increase in frequencyThe long tail is a disadvantage after a certain lengthFemale choice and male survival work against each otherRunaway selection assumes that the two traits link and grow togetherThe runaway occurs when the females with P gene have sons with both CP causing them to be linkedFemales with stronger preference for the bright males have sons that are bright and daughters htat prefer bright malesThe color and preference allels may become linked over time meaning that a stronger preference forLIFE SCI 2D03 Page 1
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