Journal of Comparative Physiology A

, Volume 195, Issue 4, pp 385–391

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

  • Kevin J. Emerson
  • Sabrina J. Dake
  • William E. Bradshaw
  • Christina M. Holzapfel
Original Paper

DOI: 10.1007/s00359-009-0416-9

Cite this article as:
Emerson, K.J., Dake, S.J., Bradshaw, W.E. et al. J Comp Physiol A (2009) 195: 385. doi:10.1007/s00359-009-0416-9


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.


Geographic variation Biological clocks Seasonality Diapause Photoperiodism 



Response to Nanda–Hamner protocols


Number of hours of light (L) and dark (D) in a given environmental cycle


Total numbers of hours in a given environmental cycle (T = L + D)


Development time


Akiake’s Information Criterion


Log-likelihood of a given model

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Kevin J. Emerson
    • 1
  • Sabrina J. Dake
    • 1
  • William E. Bradshaw
    • 1
  • Christina M. Holzapfel
    • 1
  1. 1.Center for Ecology and Evolutionary BiologyUniversity of OregonEugeneUSA

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