Phenotypic convergence along a gradient of predation risk

S. R. Dennis, Mauricio J. Carter, W. T. Hentley, A. P. Beckerman

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


A long-standing question in ecology is whether phenotypic plasticity, rather than selection per se, is responsible for phenotypic variation among populations. Plasticity can increase or decrease variation, but most previous studies have been limited to single populations, single traits and a small number of environments assessed using univariate reaction norms. Here, examining two genetically distinct populations of Daphnia pulex with different predation histories, we quantified predator-induced plasticity among 11 traits along a fine-scale gradient of predation risk by a predator (Chaoborus) common to both populations. We test the hypothesis that plasticity can be responsible for convergence in phenotypes among different populations by experimentally characterizing multivariate reaction norms with phenotypic trajectory analysis (PTA). Univariate analyses showed that all genotypes increased age and size at maturity, and invested in defensive spikes (neckteeth), but failed to quantitatively describe whole-organism response. In contrast, PTA quantified and qualified the phenotypic strategy the organism mobilized against the selection pressure. We demonstrate, at the whole-organism level, that the two populations occupy different areas of phenotypic space in the absence of predation but converge in phenotypic space as predation threat increases. This journal is

Original languageEnglish
Pages (from-to)1687-1696
Number of pages10
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1712
Publication statusPublished - 1 Jan 2011


  • Chaoborus
  • Convergence
  • Daphnia pulex
  • Phenotypic plasticity
  • Phenotypic trajectory analysis
  • Predation

ASJC Scopus subject areas

  • General Medicine
  • General Immunology and Microbiology
  • General Biochemistry,Genetics and Molecular Biology
  • General Environmental Science
  • General Agricultural and Biological Sciences


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