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Adaptiveness of Behavior

Adaptiveness of Behavior. Genetics and evolution Learning. Evolution in a nutshell. Start with variability in genes, and thus in traits Add challenges the world poses to survival and reproduction Result: genes/ traits that decrease chance of reproduction get reduced in next generation

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Adaptiveness of Behavior

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  1. Adaptiveness of Behavior • Genetics and evolution • Learning

  2. Evolution in a nutshell • Start with variability in genes, and thus in traits • Add challenges the world poses to survival and reproduction • Result: • genes/ traits that decrease chance of reproduction get reduced in next generation • genes/traits that increase chance of reproduction get increased in next generation

  3. Functionalist perspective • Physical and behavioral traits come about in the course of evolution because they promote survival and reproduction • Thus there must be a functional explanation for every trait/ behavior

  4. Functionalist perspective • Caution: • vestigial traits • traits as side effects of natural selection • chance variations (genetic drift) • Some traits do not serve an immediate function, but they won’t killya!

  5. Functionalist perspective • Caution: • “Survival of the fittest”-- misconception of natural selection as guided by moral force • term coined by Spencer, not Darwin • Misconception leads to “Naturalistic Fallacy”: belief that natural =right, moral; that if natural selection favors a behavior, that behavior must be acceptable • Examples?

  6. Environment and evolution • What is the color of the peppered moth? • pre-industrial revolution: trees covered with light-colored lichen • air pollution killed lichens, trees became dark • anti-pollution laws cleaned up air, lichens grew back • Other examples happening right under our nose?

  7. The Genetics of Behavior genes-units of heredity chromosomes-strands of genes; come in pairs deoxyribonucleic acid-DNA ribonucleic acid (RNA)-template for synthesis of proteins roles of proteins??

  8. Mendelian genetics homozygous heterozygous dominant gene recessive gene

  9. Mendelian genetics Traits caused by single gene: - PTC taste - Phenylketonuria - SLI - dogs’ fearfulness Variations of type, not degree

  10. Polygenic Traits • influenced by many genes • Differ in degree, fall on continuum • distribution described by normal curve • selective breeding can change distribution

  11. Polygenic Traits Eg: maze learning

  12. Selective breeding • Alcohol consumption in mice • Anderson and McClearn (1981) measured ethanol solution intake by fluid-deprived mice • Ratio of alcohol intake on test day/ to water intake on day prior to test=ethanol acceptance score • mice with highest scores are mated, mice with lowest scores are mated • 1st generation: mean scores of high/ low group: 0.74 0.87 • 14th generation: 0.38 1.19

  13. Genetic diversity, or: How unique are you • Humans have __ pairs of chromosomes • Imagine you only had 1 pair. How many different individuals could you produce through sexual reproduction?

  14. Chromosome Pairs n=1 M1 a b D1 a b Mom Dad You could get possible gametes from each parent: 21 = 2 or from Mom and or from Dad So you could be: Possible genotypes: 22 = 4 1 in 4 or or or

  15. Chromosome Pairs n=2 Mom: M1 M2 ab ab Dad: D1 D2 ab ab You could get: M1a/ M2a or M1a/M2b or M1b/M2a or M1b/M2b from Mom AND D1a/ D2a or D1a/D2b or D1b/D2a or D1b/D2b from Dad Possible gametes from each parent:___ You could be: M1a/ M2a / D1a/ D2a or M1/a/ M2a / D1a/D2b or M1a/ M2a / D1b/D2a or ….. Possible genotypes:____

  16. Chromosome pairs n=23 • Possible gametes from each parent: 223 • Possible genotypes: 246= more than 70 trillion! • Does not include variation due to crossing over, mutations • We are SO unique!!!

  17. However: • Guesstimate: How many genes do we have? • How many do bacteria have?

  18. % relatedness- a closer look M1 a b D1 a b Mom Dad You could get possible gametes from each parent: 21 = 2 or from Mom and or from Dad 1 in 4 or or or

  19. % relatedness- a closer look • Refers to % chance of sharing a particular gene with someone • Does NOT refer to the total amount of genetic information shared between two individuals

  20. Species-typical behaviors • Example 1: • red belly as sign stimulus for stickleback attack • Example 2 • migratory flight in indigo buntings • birds migrate at night • Emlen (1975): birds caged outside make restless futile movements towards south in fall, north in spring

  21. Species-typical behaviors • Question 1: How do they tell direction? What is their sign stimulus for migration? • Question 2: Is knowledge innate or learned? • Materials: • as many buntlings as you wish • as many undergrads as needed to watch them • several months of nothing better to do • a planetarium

  22. Emlen’s deprivation experiments • 1. Block view of sky • 2. Block view of Polaris • How do they know to use Polaris? • 3. Raise buntlings in 3 groups • group 1: no experience with night sky • group 2: normal night sky • group 3: fake sky with different fixed star (Betelgeuse) • measured: orientation of movements when exposed to normal sky in fall

  23. Emlen’s deprivation experiments • Findings: • Group 1: no consistent orientation • Group 2: away from Polaris • Group 3: away from Betelgeuse • Conclusion?

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