Lecture16 - Lecture 16 Sexual Selection(and a little bit...

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Lecture 16: Sexual Selection (and a little bit more on adaptation…) Readings: Today: 11.1 Sexual Dimorphism and Sex 11.2 Sexual Selection on Males: Competition Next week: 11.3 Sexual Selection on Males: Female Choice 11.4 Sexual Selection on Females 1 Friday, Feb.21 st
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Learning Objectives 1. Explain what is meant by the term adaptive landscape 2. Describe the effect that selection, mutation, drift and environmental shifts can have on a populations position in the adaptive landscape 3. Explain the asymmetry in parental investment between males and females and how this relates to the factors limiting reproductive success in each sex. 4. Given these different limiting factors, identify three major differences we expect to see between males and females with regard to mating and reproduction. 5. Explain how these predictions would be altered for systems where males have increased parental investment. 6. Describe the expected relationship between mating system and sexual dimorphism and explain why we expect this relationship. 7. Explain the difference between intra sexual and intersexual selection. 8. Explain why there is often a fitness trade-off between natural selection and sexual selection on traits related mating success. 2
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Adaptive Landscape The adaptive landscape presents a conceptual model for understanding factors that affect adaptation Consider the fitness of a species of insect with enzymes that allow it to feed on a specific host plant (genotype) 3
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Adaptive landscape Adaptive evolution selects for more fit genotypes population mean fitness low high genotypes 4
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Adaptive landscape Mutation smears out a population Mutation can increase or decrease fitness depending on a species’ position on the adaptive landscape population mean fitness low high genotypes 5
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Adaptive landscape Drift can can lead to an increase or decrease in fitness population mean fitness low high genotypes 6
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Adaptive landscape A shift in environment can change which genotypes are optimal An adaptive trait can become maladaptive population mean fitness low high genotypes 7
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Adaptive landscape What if there is a different adaptive peak?
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  • Spring '11
  • DAVIDSON
  • males, Sexual Selection, Sexual dimorphism

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