Alternative hypotheses (i. e 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

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

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?

Daphnia Is this phenotypic plasticity adaptive? Is there genetic variation in phenotypic plasticity itself?

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 trait value clone 2 clone 1 clone 2 clone 3 clone 3 clone 4 1 2 1 2 Environment In which of these populations can phenotypic plasticity evolve?