Ecological causes and consequences of flower color polymorphism in a self-pollinating plant (Boechera stricta)

Priya Vaidya, Ansley McDurmon, Emily Mattoon, Michaela Keefe, Lauren Carley, Cheng Ruei Lee, Robin Bingham, Jill T. Anderson

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Intraspecific variation in flower color is often attributed to pollinator-mediated selection, yet this mechanism cannot explain flower color polymorphisms in self-pollinating species. Indirect selection mediated via biotic and abiotic stresses could maintain flower color variation in these systems. The selfing forb, Boechera stricta, typically displays white flowers, but some individuals produce purple flowers. We quantified environmental correlates of flower color in natural populations. To disentangle plasticity from genotypic variation, we performed a multiyear field experiment in five gardens. In controlled conditions, we evaluated herbivore preferences and the effects of drought stress and soil pH on flower color expression. In natural populations, purple-flowered individuals experienced lower foliar herbivory than did their white-flowered counterparts. This pattern also held in the common gardens. Additionally, low-elevation environments induced pigmented flowers (plasticity), and the likelihood of floral pigmentation decreased with source elevation of maternal families (genetic cline). Viability selection favored families with pigmented flowers. In the laboratory, herbivores exerted greater damage on tissue derived from white- vs purple-flowered individuals. Furthermore, drought induced pigmentation in white-flowered lineages, and white-flowered plants had a fecundity advantage in the well-watered control. Flower color variation in selfing species is probably maintained by herbivory, drought stress, and other abiotic factors that vary spatially.

Original languageEnglish
Pages (from-to)380-392
Number of pages13
JournalNew Phytologist
Volume218
Issue number1
DOIs
StatePublished - Apr 2018

Keywords

  • Boechera stricta
  • drought
  • flower color
  • genetic cline
  • herbivory
  • natural selection
  • phenotypic plasticity

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