BS 110 Notes 9-24-10

BS 110 Notes 9-24-10 - BS 110 Notes 9-24-2010 Role of...

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BS 110 Notes 9-24-2010 Role of Natural Selection All or none phenomenon – an individual had favorable characteristics and survived to reproduce or did not have favorable characteristics and did not survive; gradual changes in the number of individuals through time Affects distribution of characteristics within a population: o Stabilizing o Disruptive o Directional o Sexual Types of selection: Stabilizing – decrease in the numbers of individuals with extreme phenotypes and an increase in the numbers of individuals with intermediate phenotypes. o Ex: Swiss Starling – offspring from a clutch size of 4-5 have much higher survivorship than offspring from a clutch size of 3 or less or 6 or more. Why? How long the birds mate Amount of protein in the egg Thickness of the shell of the egg Disruptive – higher in the numbers of individuals with extreme phenotypes and lower in the numbers of individuals with intermediate phenotypes o Ex: Coho salmon in Pacific Northwest – females at age 3 move from the ocean to
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This note was uploaded on 01/31/2011 for the course BS 110 taught by Professor S.lawrence during the Fall '07 term at Michigan State University.

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BS 110 Notes 9-24-10 - BS 110 Notes 9-24-2010 Role of...

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