Evolution of photoperiodic time measurement is independent of the circadian clock in the pitcher-plant mosquito, Wyeomyia smithii

Kevin J. Emerson, Sabrina Dake, William E. Bradshaw, Christina M. Holzapfel

Research output: Contribution to journalArticle

21 Scopus citations


For over 70 years, researchers have debated whether the ability to use day length as a cue for the timing of seasonal events (photoperiodism) is related to the endogenous circadian clock that regulates the timing of daily events. Models of photoperiodism include two components: (1) a photoperiodic timer that measures the length of the day, and (2) a photoperiodic counter that elicits the downstream photoperiodic response after a threshold number of days has been counted. Herein, we show that there is no geographical pattern of genetic association between the expression of the circadian clock and the photoperiodic timer or counter. We conclude that the photoperiodic timer and counter have evolved independently of the circadian clock in the pitcher-plant mosquito Wyeomyia smithii and hence, the evolutionary modification of photoperiodism throughout the range of W. smithii has not been causally mediated by a corresponding evolution of the circadian clock.

Original languageEnglish (US)
Pages (from-to)385-391
Number of pages7
JournalJournal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
Issue number4
Publication statusPublished - Apr 2009
Externally publishedYes



  • Biological clocks
  • Diapause
  • Geographic variation
  • Photoperiodism
  • Seasonality

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Behavioral Neuroscience

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