Cutter_Lecture_07 - NaturalSelectionandAdaptation 1...

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1 Natural Selection and Adaptation
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A characteristic that enhances the reproductive success of organisms that bear it Relative to alternative character states in the population or in the ancestral population Adaptations arise due to natural selection Consistent differential reproductive success of organisms with a particular characteristic What is an adaptation? 2
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Developmental plasticity in leaf morphology 3 Philodendron
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Cooperative behavior in weaver ants 4 Oecophylla weaver ants Sterile workers cooperate in next formation Silk produced by larvae, carried by workers
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Fruit maggot flies mimic jumping spiders 5 Rhagoletis pomonella Rhagoletis zephyria
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NS = consistent difference in fitness between alternative phenotypes Fitness = reproductive success Probability of survival to reproductive age Average number of offspring via female function Average number of offspring via male function Sexual selection: a kind of natural selection Variation in offspring produced due to competition for mates Selection Evolution Evolution can result from selection among phenotypes Natural selection defined 6
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Natural selection can operate, but an evolutionary response to selection requires heritable variation Selection VS. Evolution 7 Generation 1 eggs Generation 1 adults Generation 2 eggs Strong viability selection against blue individuals…BUT no heritability No response to selection…No evolution Generation 1 eggs Generation 1 adults Generation 2 eggs Strong viability selection against blue individuals Evolutionary response yields increase in red abundance
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Fitness meaningful only when averaged across members of a phenotypic (or genotypic) class An individual is not necessarily representative of the group
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Cutter_Lecture_07 - NaturalSelectionandAdaptation 1...

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