Mimetic Divergence and the Speciation Continuum in the Mimic Poison Frog Ranitomeya imitator

Evan Twomey, Jacob Schack Vestergaard, Pablo J. Venegas, Kyle Summers

Research output: Contribution to journalJournal articleResearchpeer-review


While divergent ecological adaptation can drive speciation, understanding the factors that facilitate or constrain this process remains a major goal in speciation research. Here, we study two mimetic transition zones in the poison frog Ranitomeya imitator, a species that has undergone a Mullerian mimetic radiation to establish four morphs in Peru. We find that mimetic morphs are strongly phenotypically differentiated, producing geographic clines with varying widths. However, distinct morphs show little neutral genetic divergence, and landscape genetic analyses implicate isolation by distance as the primary determinant of among-population genetic differentiation. Mate choice experiments suggest random mating at the transition zones, although certain allopatric populations show a preference for their own morph. We present evidence that this preference may be mediated by color pattern specifically. These results contrast with an earlier study of a third transition zone, in which a mimetic shift was associated with reproductive isolation. Overall, our results suggest that the three known mimetic transition zones in R. imitator reflect a speciation continuum, which we have characterized at the geographic, phenotypic, behavioral, and genetic levels. We discuss possible explanations for variable progress toward speciation, suggesting that multifarious selection on both mimetic color pattern and body size may be responsible for generating reproductive isolation.
Original languageEnglish
JournalThe American Naturalist
Issue number2
Pages (from-to)205-224
Number of pages20
Publication statusPublished - 2016


  • Animals
  • Animals, Poisonous
  • Anura
  • Biological Mimicry
  • Female
  • Gene Flow
  • Male
  • Mating Preference, Animal
  • Microsatellite Repeats
  • Peru
  • Pigmentation
  • Reproductive Isolation
  • approximate Bayesian computation
  • ecological speciation
  • landscape genetics
  • mate choice
  • mimicry
  • Ecology, Evolution, Behavior and Systematics
  • Approximate bayesian computation
  • Ecological speciation
  • Landscape genetics
  • Mate choice
  • Mimicry
  • allopatry
  • Bayesian analysis
  • color morph
  • divergence
  • frog
  • genetic differentiation
  • reproductive isolation
  • selection
  • speciation (biology)
  • Dendrobates imitator
  • Dendrobatidae
  • Evolution
  • Genetics - Animal
  • Genetics - Population genetics
  • Ecology: environmental biology - General and methods
  • Ecology: environmental biology - Animal
  • Amphibians, Animals, Chordates, Nonhuman Vertebrates, Vertebrates
  • gene flow
  • population genetic differentiation
  • neutral genetic divergence
  • speciation continuum
  • mimetic radiation
  • mimetic divergence
  • divergent ecological adaptation


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