BIO3082 Lecture Notes - Lecture 7: Phenology, Global Warming, Genotype
Lecture 7 – Adaptation and Plasticity
Adapt, Move or Die Hypothesis
• Organisms have three options when limits are exceeded
• Adapt
o Organisms can phenotypically respond or genetically adapt to
physiological pressures
• Move
o Organisms are changing their distribution across space (range shifts)
and time (phenology shifts)
• Die
o Many organisms will not cope with the pace of change → leading to
local and global extinctions
Organisms can Evolve in Response to Climate Change
• Rates of current warming are historically unprecedented
• Organisms will need to rapidly adapt if they are to colonise projected climate
niches
o May require rates of niche evolution over 10,000 times those of
historical rates
• Rapid adaptation is possible through two main routes
o Phenotypic plasticity buffers populations against the immediate
impacts of environmental change and provides time for genetic
adaptation to catch up
o There is growing evidence that natural selection can drive evolutionary
rescue of populations with fast growth rates or standing genetic
variation (genotypic diversity)
▪ Low genetic variation in population – not many ways
organisms can deal with selection pressure
▪ High genetic variation – phenotypic variation → adaptive
phenotypes selected
Phenotypic Plasticity Facilitates Climate Responses
• Behavioural
o E.g. lizards retreat to shade in response to avoid critical surface
temperature
• Physiological
Phenotypic Plasticity vs. Genetic Adaptation
• A population of a single phenotype
having multiple phenotypes
• Changes in behaviour, morphology,
metabolism in response to environmental
change
• Modulation of the phenotype of
organisms of given genotype in response
to environment
• Changes can be permanent or reversible
• Short or long term
• Sometimes heritable due to epigenetics
• Adaptive change in the genotype of
organisms
• Not wide spread
• Results from natural selection for
resultant phenotypes that best suit
environment
• Changes are heritable given they occur in
DNA sequences
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