U of M ANTH 1001 - Lecture 4 9-12-17 Sexual Selection (7 pages)

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Lecture 4 9-12-17 Sexual Selection



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Lecture 4 9-12-17 Sexual Selection

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Pages:
7
School:
University of Minnesota- Twin Cities
Course:
Anth 1001 - Human Evolution
Human Evolution Documents
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9 13 2017 1 Today Sexual Selection Why do traits persist that seem detrimental to survival 2 1 9 13 2017 The Peacock Problem Darwin The sight of the peacock s tail makes me sick His solution sexual selection a type of NS 3 Evolutionary Trade off s in Sexual Selection 1 Male male Competition Exaggerated secondary sexual characteristics Sexual dimorphism Conflict between fertility and survival 2 Female Mate Choice Handicaps as honest advertisements of genetic quality 4 2 9 13 2017 Sexual Selection Female Mate Choice 5 Sexual Selection History of an Idea Darwin s View Pre existing female esthetic is the force selecting for exaggerated characteristics in males Ronald Fisher s Sexy Son Hypothesis and Runaway Sexual Selection Females choose males with a trait that will be preferred by females so they can have sexy sons Amotz Zahavi s Handicap Hypothesis Males with exaggerated traits are at a disadvantage Such a male must be VERY good to 6 still be alive 3 9 13 2017 Honest Advertising Hypothesis Building upon Zahavi Male exaggerated traits are indicators of male condition The features that are used to indicate condition cannot be lied about the indicator must be honest Dishonest indicators cannot evolve because females will be selected to ignore them being lied to is costly 7 Honest indicator example bird coloration Illness parasites starvation inevitably create byproducts These byproducts interfere with the production of certain pigments in birds Sub optimal birds are duller in color than healthy birds We see only these colors used in the lesschoosy sex s exaggerated coloration 8 4 9 13 2017 Difficulties with Darwin s conception of evolution by Natural Selection Did not have a working model of inheritance Blended inheritance Inheritance of acquired traits No clear account of how species formed Genes Alleles DNA all unknown 9 Difficulties with Darwin s conception of evolution by Natural Selection Could only discuss evolution in terms of phenotype one s physical traits and not genotype one s genetic make up Accurate estimate of the Earth s age was still unknown 10 5 9 13 2017 Difficulties with Darwin s conception of evolution by Natural Selection BUT these difficulties did not render his theories false but make it more difficult for him to win acceptance for them With a modern understanding of genetics and geology Darwin s theories of evolution 5 theories are fully supported 11 Biological Evolution It s NOT just change over time Lots of things change over time Natural selection is the process of descent through modification 12 http evolution berkeley edu evosite 6 9 13 2017 Any Questions 13 7


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