Climate Change

  • Global dist. of species are mostly determined by climate

  • Phenotypic adaptations to local conditions (among pops within species) are also often associated with climate

  • climate is changing with atmospheric greenhouse gas (GHG) levels

    • if a sp. range is primarily determined by climate then suitable conditions are moving to new geographic areas

    • novel climates may emerge

    • some current climatic conditions may disappear

  • There are many conservation challenges associated with climate change

Potential responses to climate change

Phenotypic plasticity

  • when the same genotype produces different phenotypes in diff environments

    • phenotype often the result of genotype and environment

    • is environment changes, then phenotype may change with no genetic change

  • env. can change phenology (the timing of biological events), growth, morphology, reprod traits (among others)

  • individuals and pops can vary genetically in their capacity for phenotypic plasticity

  • its an effective mechanism for short-term env. shifts but prob insufficient over the long term. predicted climate change bc it cant shift phenotype to the extent that selection could

  • evolutionary rescue: process whereby a pop recovers demographically from an env change as a result of natural selection

  • not all phenotypic changes caused by a warming climate are harmful

  • when low temps limit pops, warmer conditions can favor growth in some species

Adaptation

  • capacity to adapt is substantial: many species adapted to local conditions during or since the last glacial max

    • requires sufficient genetic variation

  • rates of anthro. climate change greatly exceed those observed during the pleistocene

  • theoretical predictions for the max rate of change a pop can withstand and recover thru evolutionary rescue are based on:

    • genetic variation present

    • Fecundity

    • Ne

    • Environmental stochasticity

    • Strength of selection

  • beyond a threshold rate of change, the pop will not be able to adapt fast enough to keep up with the necessary rate of change in optimum phenotype to maintain fitness

  • over time, the pop will lag increasingly behind its climate fitness optimum

  • when adaptational lag btwn mean pop phenotype and optimum phenotype is too great, extirpation is likely