Moreno, João MJesus, Tiago F.Coelho, Maria ManuelaSousa, Vitor C2021-03-232021-03-232021-03-08Moreno, J.M., Jesus, T.F., Coelho, M.M. et al. Adaptation and convergence in circadian‐related genes in Iberian freshwater fish. BMC Ecol Evo 21, 38 (2021). https://doi.org/10.1186/s12862-021-01767-zhttp://hdl.handle.net/10451/46979The circadian clock is a biological timing system that improves the ability of organisms to deal with environmental fluctuations. At the molecular level it consists of a network of transcription-translation feedback loops, involving genes that activate (bmal and clock - positive loop) and repress expression (cryptochrome (cry) and period (per) - negative loop). This is regulated by daily alternations of light but can also be affected by temperature. Fish, as ectothermic, depend on the environmental temperature and thus are good models to study its integration within the circadian system. Here, we studied the molecular evolution of circadian genes in four Squalius freshwater fish species, distributed across Western Iberian rivers affected by two climatic types with different environmental conditions (e.g., light and temperature). S. carolitertii and S. pyrenaicus inhabit the colder northern region under Atlantic climate type, while S. torgalensis, S. aradensis and some populations of S. pyrenaicus inhabit the warmer southern region affected by summer droughts, under Mediterranean climate type.engAdaptationCircadian rhythmEvolutionary convergenceFreshwater fshSelectionjournal article10.1186/s12862-021-01767-z