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Lecture 4

Week 4.pdf

2 Pages
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Department
Psychology
Course Code
PSYCH 2TT3
Professor
Reuven Dukas

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PNB  2XC3   Week  4   Oct.  1,  2013   Fitness  Consequences   • Fitness:  lifetime  reproduction  success,  which  is  a  product  of  reproduction  rate  &  the  length  of  reproductive  lifespan.   • i.e.  Female  1  lays  10  eggs/day  &  lives  for  20  days.  Female  2  lays  15  eggs/day  &  lives  for  10  days.  Female  1  has  higher   fitness  (200  vs.  150  eggs).   • Even  a  small  diff  in  fitness  (1%)  can  have  strong  effects  on  evolution.     Evolution  of  Anti-­‐predator  Behavior  in  Guppies   • Small  predators  can  only  prey  on  small  fish,  while  large  predators  p rey  on  adults.   • Moved  guppies  into  artificial  ponds .  After  ½  a  year,  introduced  small   &  large  predators.   • Recorded  the  #  &  brightness  of  spots  on  males  after  4  &  10  generations   • Spots  attract  predators.  In  high  predation,  males  lose  spots  to  avoid  predators  (∴  selection  for  fewer  spots).  In  low   predation,  males  gain  spots  to  attract  females  ( ∴  selection  for  more  spots).   • Males  mature  at  a  younger  age  in  high  vs.  low  predation.  WHY?  Since  more  of  the  pop  is  dying  off,  they  need  to   reproduce  more  often  ∴  maturing  early  allows  more  reproduction.   • Fish  at  high  predation  pools  may  have  evolved  tendencies  to  form  larger  groups  &  more  effective  predator   inspection  (more  frequent  &  from  farther  distance).           Fish  Survival  Under  High  Predation   • Experiment:  Take  lab-­‐born  fish  from  pops  that  have  evolved  in  high  predation  pools   &  low  predation  pools  &  place   them  in  high  predation  environment.   • Would  high  predation  fish  have  higher  survival  than  low  predation  fish?   • Results:  Fish  from  pops  that  have  evolved  in  high  predation  pools   =  higher  survival  under  high  predation  than  fish   from  pops  that  have  evolved  in  low  predation  pools.     Most  Traits  are  Polygenic   • Polygenic:  Many  genes  are  involved  in  the  trait’s  expression   • Quantitative  Trait  Loci  (QTL):  The  genes  that  control  polygenic  traits   • Mapping  of  QTLs  =  If  the  inheritance  of  a  g enetic  marker  is  associated  w/  the  inheritance  of  a  particular  trait,  the   marker  must  be  linked  to  the  trait.   • QTLs  for  emotionality  -­‐  Mice   o Dangerous  for  mice  to  be  in  open  field  b/ c  of  predators  =  anxious   o Levels  of  activity  &  defecation  are  heritable  &  negatively  correlated   o 2  QTLs  were  identified  on  the  mouse  chromosome  1  &  12 .  These  may  be  related  to  human  genes  affecting   anxiety.   • What  is  the  adaptive  significance  of  anxiety?   o Certain  emotions  such  as  anxiety,  depression   &  love  are  adaptive.   o High  Anxiety  =  less  risk -­‐taking  behaviour     DNA  Microarrays   • Each  spot  in  a  microarray  contains  numerous  copies  of  ssDNA  representing  a  gene   • Collect  mRNA  from  2  samples  &  transcribe  to  more  stable  cDNA.   • Mark  each  sample  w/  a  distinct  fluorescent  label  &  a pply  to  array.   • Binding  indicates  that  a  gene  was  active   • Calculate  the  ratio  of  red  (untreated)  to  green  (treated)  at  each  spot     Genetics  of  Behavioural  Development   • Treatment:  Add  either  old  or  young  bees  (pink)   •
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