Plant reproductive strategies under environmental stress
Simons, Andrew .
Life-history evolution under changing environments.
Environmental change can lead to extinction of previously well-adapted organisms. Adaptive tracking and phenotypic plasticity are well studied modes of response to changing environments. The evolution of risk averse, "bet-hedging" strategies is often overlooked, but may also be an important mode of response. In a review of empirical evidence for bet hedging, I find that the taxonomic distribution in over 100 studies of bet hedging suggests their ubiquity, yet the empirical evidence tends to be weak. I report on two empirical tests of bet hedging from my lab. First, in a five-year study of Lobelia inflata (Campanulaceae), we find the magnitude of fluctuating selection acting on the timing of seed germination to be sufficient to explain the degree of bet-hedging diversification behavior characteristic of individuals of this species. Second, we borrow a fungal model organism (Neurospora crassa) to test Cohen's classic 1966 model of seed dormancy as bet hedging. We allow ascospore dormancy fraction to evolve under five selection regimes that differ in the frequency of 'bad' years. Dormancy fraction evolved in proportion to the frequency of bad years, a result consistent with Cohen's predictions. Differential survival through environmental change may thus be mitigated by the evolution of bet hedging, and further knowledge of the prevalence of bet hedging in nature is needed.
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1 - Carleton University, Department of Biology, Nesbitt 209, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
life history evolution
Presentation Type: Symposium or Colloquium Presentation
Location: Westminster Room/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 10:25 AM