Adaptation

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Adaptation

• The match of an organism to its environment in
  response to past selection
• Adaptation is NOT acclimatization but an evolved
  response

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Evolution by natural selection

• Evolution change in gene frequencies over time,
  due to selection or chance events (i.e. drift)
• Requires variation, genetic basis, fitness
  differences

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Evolution An example

• Stanton, Snow, Handel. 1986. Science 232
  1625-1627
• Wild radish flower color (white or yellow
  variation) controlled by one genetic locus (
  inheritance)

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Evolution An examplefitness differences
Replicate
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Evolution An example

• Yellow flowers have greater paternity than white
  flowers (variation affects fitness)
• Change in frequency of color variants in
  offspring generation evolution

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CKHs ecotypes the classic study of adaptation

• Clausen (geneticist), Keck (taxonomist), and
  Hiesey (ecophysiologist) worked together in
  California in the 1920s

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CKHs ecotypes

• Ecotype the product of a genetic response to a
  habitat
• Best discerned through transplant experiments
  if trait differences maintained in common garden,
  then they have genetic basis

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CKHs ecotypes

• Collected plants along 300 km transect, sea level
  to 3000 m elevation
• Cloned plants, three common gardens
• Measured growth, survival, fecundity for 16 years

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CKHs ecotypes
Height variation in Achillea
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Transplant gardens
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Ecotypes of cinquefoil (Potentilla glandulosa)
Stanford Mather Timberline
Native to
Stanford Mather Timberline
Grown at
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CKHs ecotypes

• Limiting factor temperature
• Adaptations frost tolerance, flowering
  phenology (early at high elevation), leaf
  pubescence
• Adaptations can be morphologically or
  developmentally complex

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The home team advantage
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The home team advantage

• Local adaptation genotypes from on-site perform
  better than those from off-site
• An important concept for restoration ecology
  Montalvo et al. 1997. Restoration biology a
  population biology perspective. Restoration
  Ecology 5277-290

15
Heavy metal tolerance

• Limiting factor is not LACK of resource, but TOO
  MUCH
• Mine tailings contaminated with zinc, copper
  most plants cant survive

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Heavy metal tolerance

• Local adaptation in grasses within a meter of
  mine boundary
• Anthoxanthum odoratum, Agrostis tenuis

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Heavy metal tolerance

• Adaptations
• Physiological tolerance
• Phenology and type of reproduction (early,
  selfing on mine)

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Phenotypic plasticity

• If the same genotype exhibits a different
  phenotype in different environments, that is
  phenotypic plasticity

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Phenotypic plasticity

• Impatiens capensis from sun and shade

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Phenotypic plasticity
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Phenotypic plasticity
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Is plasticity adaptive?

• Fitness consequences of plasticity in Impatiens

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Main points for adaptation and plasticity

• Remember adaptation must have a genetic basis
  we dont mean acclimatization
• Plasticity has a genetic basis and can be
  adaptive, but allows for generalized (not
  ecotypic/specialized) response