Seed germination in desert annuals: An empirical test of adaptive bet hedging

M. J. Clauss, D. L. Venable

Research output: Contribution to journalArticle

194 Scopus citations

Abstract

Temporal variability in survivorship and reproduction is predicted to affect the evolution of life-history characters. Desert annual plants experience temporal variation in reproductive success that is largely caused by precipitation variability. We studied several populations of the desert annual Plantago insularis along a precipitation gradient. Whereas models of bet hedging in unpredictable environments generally predict one optimal germination fraction for a population, empirical studies have shown that environmental conditions during germination can cause a range of germination fractions to be expressed. In a 4-yr field study, we found that populations in historically more xeric environments had lower mean germination fractions, as is predicted by bet-hedging models. However, populations exhibited significant variation in germination among years. Two experimental studies measuring germination under several environment conditions were conducted to elucidate the source of this in situ variation. Germination fractions exhibited phenotypic plasticity in response to water availability and date within the season. Populations differed in their norms of reaction such that seeds from more xeric populations germinated under less restrictive conditions. A pattern of delayed germination consistent with among-year bet-hedging predictions arose in the field through the interaction of seed germinability and the distribution of environmental conditions during germination.

Original languageEnglish (US)
Pages (from-to)168-186
Number of pages19
JournalAmerican Naturalist
Volume155
Issue number2
DOIs
StatePublished - Jan 1 2000

Keywords

  • Bet hedging
  • Desert annual plant
  • Life history
  • Phenotypic plasticity
  • Seed germination
  • Variable environments

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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