Evolutionary Ecology

, Volume 23, Issue 3, pp 373–388

Plastic bet-hedging in an amphicarpic annual: an integrated strategy under variable conditions

  • Asaf Sadeh
  • Hagai Guterman
  • Mordechai Gersani
  • Ofer Ovadia
Original Paper

Abstract

Amphicarpy is a form of diversified bet-hedging expressed mostly in annual plants, where two types of offspring are produced with two distinct ecological roles: long-range aerial dispersers and highly competitive subterranean, sedentary fruit. Emex spinosa is a semi-arid, amphicarpic annual, inhabiting habitats with different levels of environmental variation. We tested the hypothesis that, in E. spinosa, bet-hedging may be “fine-tuned” by plasticity in the phenotype ratio (aerial/subterranean fruit mass) as a function of environmental conditions. We conducted a greenhouse experiment, manipulating nutrient availability and intraspecific density, to determine the pattern of ratio shifts. In order to determine whether the integrated strategy is an adaptation to variable habitats, a similar common garden experiment was conducted, comparing two natural populations differing in environmental variability. The offspring ratio shifted in response to both nutrient availability and plant density. In pots containing single plants the ratio increased steeply with nutrient availability, while in pots containing eight plants a more moderate increase occurred. These shifts were the result of plasticity in allocation to both achene types, as well as ontogenetic effects on aerial achene production. The degree of response increased with the heterogeneity of the habitat of origin. We found evidence for an adaptive integrated strategy, with bet-hedging “fine-tuned” by phenotypic plasticity. Strenuous conditions tended to shift the offspring ratio towards securing subterranean reproductive success, while favorable conditions resulted in a shift towards dispersible achenes.

Keywords

Bet-hedging Seed dispersal Emex spinosa Integrated strategies Life history Phenotypic plasticity Sibling competition Variable environments 

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Asaf Sadeh
    • 1
  • Hagai Guterman
    • 1
  • Mordechai Gersani
    • 1
  • Ofer Ovadia
    • 1
  1. 1.Department of Life SciencesBen-Gurion University in the NegevBeer ShevaIsrael

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