University of Oulu

Merckx, T., Nielsen, M. E., Heliölä, J., Kuussaari, M., Pettersson, L. B., Pöyry, J., Tiainen, J., Gotthard, K., & Kivelä, S. M. (2021). Urbanization extends flight phenology and leads to local adaptation of seasonal plasticity in Lepidoptera. Proceedings of the National Academy of Sciences 118(40), e2106006118),

Urbanization extends flight phenology and leads to local adaptation of seasonal plasticity in Lepidoptera

Saved in:
Author: Merckx, Thomas1,2; Nielsen, Matthew E.3; Heliölä, Janne4;
Organizations: 1Ecology and Genetics Research Unit, University of Oulu, 90014 Oulu, Finland
2Biology Department, Vrije Universiteit Brussel, 1050 Brussels, Belgium
3Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden
4Biodiversity Centre, Finnish Environment Institute, 00790 Helsinki, Finland
5Biodiversity Unit, Department of Biology, Lund University, 223 62 Lund, Sweden
6Natural Resources Institute Finland, 00790 Helsinki, Finland
7Lammi Biological Station, University of Helsinki, 16900 Lammi, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.5 MB)
Persistent link:
Language: English
Published: National Academy of Sciences of the United States of America, 2021
Publish Date: 2021-11-02


Urbanization is gaining force globally, which challenges biodiversity, and it has recently also emerged as an agent of evolutionary change. Seasonal phenology and life cycle regulation are essential processes that urbanization is likely to alter through both the urban heat island effect (UHI) and artificial light at night (ALAN). However, how UHI and ALAN affect the evolution of seasonal adaptations has received little attention. Here, we test for the urban evolution of seasonal life-history plasticity, specifically changes in the photoperiodic induction of diapause in two lepidopterans, Pieris napi (Pieridae) and Chiasmia clathrata (Geometridae). We used long-term data from standardized monitoring and citizen science observation schemes to compare yearly phenological flight curves in six cities in Finland and Sweden to those of adjacent rural populations. This analysis showed for both species that flight seasons are longer and end later in most cities, suggesting a difference in the timing of diapause induction. Then, we used common garden experiments to test whether the evolution of the photoperiodic reaction norm for diapause could explain these phenological changes for a subset of these cities. These experiments demonstrated a genetic shift for both species in urban areas toward a lower daylength threshold for direct development, consistent with predictions based on the UHI but not ALAN. The correspondence of this genetic change to the results of our larger-scale observational analysis of in situ flight phenology indicates that it may be widespread. These findings suggest that seasonal life cycle regulation evolves in urban ectotherms and may contribute to ecoevolutionary dynamics in cities.

see all

Series: Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
ISSN-E: 1091-6490
ISSN-L: 0027-8424
Volume: 118
Issue: 40
Article number: e2106006118
DOI: 10.1073/pnas.2106006118
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: This study was financed by the Academy of Finland (Grant Nos. 314833 and 319898 to S.M.K.), the Swedish Research Council (Grant No. VR 2017‐04500 to K.G.), and the Swedish Environmental Protection Agency (Grant No. 227-20-006 to L.B.P.), while the Finnish Ministry of the Environment supported the Finnish moth–monitoring scheme.
Academy of Finland Grant Number: 314833
Detailed Information: 314833 (Academy of Finland Funding decision)
319898 (Academy of Finland Funding decision)
Copyright information: © 2021 The Author(s). This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).