University of Oulu

Lankinen P, Kastally C, Hoikkala A. Nanda-Hamner Curves Show Huge Latitudinal Variation but No Circadian Components in Drosophila Montana Photoperiodism. Journal of Biological Rhythms. 2021;36(3):226-238. doi:10.1177/0748730421997265

Nanda-Hamner curves show huge latitudinal variation but no circadian components in Drosophila montana photoperiodism

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Author: Lankinen, Pekka1; Kastally, Chedly1; Hoikkala, Anneli2
Organizations: 1Department of Ecology and Genetics, University of Oulu, Oulu, Finland
2Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.7 MB)
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Language: English
Published: SAGE Publications, 2021
Publish Date: 2021-06-11


Insect species with a wide distribution offer a great opportunity to trace latitudinal variation in the photoperiodic regulation of traits important in reproduction and stress tolerances. We measured this variation in the photoperiodic time-measuring system underlying reproductive diapause in Drosophila montana, using a Nanda-Hamner (NH) protocol. None of the study strains showed diel rhythmicity in female diapause proportions under a constant day length (12 h) and varying night lengths in photoperiods ranging from 16 to 84 h at 16°C. In the northernmost strains (above 55°N), nearly all females entered diapause under all photoperiods and about half of them even in continuous darkness, while the females of the southern strains showed high diapause proportions only in the circadian 24 h photoperiod. Significant correlation between the strains’ mean diapause proportions in ≥ 24 h photoperiods and critical day length (CDL; half of the females enter diapause) suggests at least partial causal connection between the traits. Interestingly, females of the northern strains entered diapause even in ≤ 24 h photoperiods, where the night length was shorter than their critical night length (24 h — CDL), but where the females experienced a higher number of Light:Dark cycles than in 24 h photoperiods. NH experiments, performed on the control and selection lines in our previous selection experiment, and completed here, gave similar results and confirmed that selection for shorter, southern-type CDL decreases female diapausing rate in non-circadian photoperiods. Overall, our study shows that D. montana females measure night length quantitatively, that the photoperiodic counter may play a prominent but slightly different role in extra short and extra long photoperiods and that northern strains show high stability against perturbations in the photoperiod length and in the presence of LD cycles. These features are best explained by the quantitative versions of the damped external coincidence model.

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Series: Journal of biological rhythms
ISSN: 0748-7304
ISSN-E: 1552-4531
ISSN-L: 0748-7304
Volume: 36
Issue: 3
Pages: 226 - 238
DOI: 10.1177/0748730421997265
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
Copyright information: © 2021 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 License ( which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (