Talk  D20SY05RT11:42R1

When in doubt, hedge your bets. Diversification and phenotypic plasticity in Spirodela polyrhiza (L.) (Greater duckweed)

Author(s): Compton ME, Simons AM

Summary:

Reliable environmental cues may lead to the evolution of adaptive phenotypic plasticity. However, when cues are unreliable and the environment is thus unpredictable, so-called “bet hedging” is expected to evolve. Bet hedging characters decrease variance in fitness, and short-term success (i.e. expected fitness) is sacrificed for success over generations. Empirical support for bet hedging is limited, but this mode of response is increasingly being recognized as an important response to environmental variance. Here, the phenology of turion formation in greater duckweed (Spirodela polyrhiza (L.)) is used to study bet hedging and phenotypic plasticity in the field. Turions are heavy, non-vegetative fronds that sink into the sediment, allowing this free-floating hydrophyte to persist through unfavourable conditions. Mean days to turion formation was found to differ among pond environments-fronds from ponds of greater unpredictability had greater variability in the timing of turion formation. In a field transplant study, fronds from the more predictable pond environment demonstrated plasticity in turion formation when subjected to an environment of greater environmental variability. The success of S. polyrhiza may be attributed to evolved strategies, which are dependent on the availability of dependable cues. This study provides evidence of the occurrence of both bet hedging and plasticity in fluctuating pond environments.

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