Adaptiveness of Behavior Genetics and evolution Learning.
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Transcript of Adaptiveness of Behavior Genetics and evolution Learning.
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– genes/traits that increase chance of reproduction get
increased in next generation
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
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!
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?
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?
The Genetics of Behaviorgenes-units of hereditychromosomes-strands of genes; come in pairsdeoxyribonucleic acid-DNAribonucleic acid (RNA)-template for synthesis of proteinsroles of proteins??
Mendelian genetics
homozygousheterozygousdominant generecessive gene
Mendelian geneticsTraits caused by single gene:
- PTC taste- Phenylketonuria- SLI- dogs’ fearfulness
Variations of type, not degree
Polygenic Traits • influenced by many genes
• Differ in degree, fall on continuum
• distribution described by normal curve
• selective breeding can change distribution
Polygenic Traits
Eg: maze learning
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
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?
Chromosome Pairs n=1
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
or or or 1 in 4
M1 a b D1 a b
Chromosome Pairs n=2Mom: M1 M2
ab abYou 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:____
Dad: D1 D2ab ab
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!!!
However:
• Guesstimate: How many genes do we have?
• How many do bacteria have?
% relatedness- a closer look
Mom Dad
You could get
possible gametes from each parent: 21 = 2
or from Mom and or from Dad
or or or 1 in 4
M1 a b D1 a b
% 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
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
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
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
Emlen’s deprivation experiments• Findings:
• Group 1: no consistent orientation
• Group 2: away from Polaris
• Group 3: away from Betelgeuse
• Conclusion?