Alternative hypotheses (i.e., other than evolution by natural selection) to explain phenotypic change

1
Alternative hypotheses (i.e., other than
evolution by natural selection) to explain
phenotypic change

• Well-designed and well-executed experiments
  ALWAYS distinguish between competing hypotheses
• Phenotypic plasticity
• Random genetic drift
• Sexual selection
• Kin selection

2
Phenotypic plasticity
Expression of different phenotypes by the same
genotype, often in response to environment May
be adaptive, non-adaptive, or maladaptive
3
Heritability

• VP phenotypic variance
• VG total genetic variance
• VA additive genetic variance
• VD dominance genetic variance
• VE environmental variance
• VGxE genotype x environment variance
• VP VA VD VE VGxE
• VG VA VD
• H2 VG / VP
• h2 VA / VP
• When clones are planted in common gardens, are we
  estimating H2 or h2?
• With parent-offspring regression, are we
  estimating H2 or h2?

4
Daphnia
Is this phenotypic plasticity adaptive? Is there
genetic variation in phenotypic plasticity itself?
5
Is there genetic variation for plasticity?
Multiple isogenic lines (e.g., clones), grown in
two or more common gardens having different
environments Compare norms of reaction
clone 1
clone 2
clone 1
clone 2
clone 3
clone 3
clone 4
1
1
2
2
Environment
In which of these populations can phenotypic
plasticity evolve?