Adaptation and convergence in circadian-related genes in Iberian freshwater fish.

摘要: The circadian clock is a biological timing system that improves the ability of organisms to deal with environmental fluctuations. At molecular level it consists network transcription-translation feedback loops, involving genes activate (bmal and – positive loop) repress expression (cryptochrome (cry) period (per) – negative loop). This regulated by daily alternations light but can also be affected temperature. Fish, as ectothermic, depend on temperature thus are good models study its integration within system. Here, we studied evolution in four Squalius freshwater fish species, distributed across Western Iberian rivers two climatic types different conditions (e.g., temperature). S. carolitertii pyrenaicus inhabit colder northern region under Atlantic climate type, while torgalensis, aradensis some populations warmer southern summer droughts, Mediterranean type. We identified 16 circadian-core species using comparative transcriptomics approach. detected evidence selection 12 these methods based dN/dS. Positive was mainly found cry per negative loop, 55 putatively adaptive substitutions, located protein domains. Evidence for predominant By predicting features changes at sites impact thermostability changing their aliphatic index isoelectric point. Additionally, nine genes, phylogenetic clustering belong clades basins similar indicated evolutionary convergence. increased nonsynonymous substitution rate convergent lineages, likely due 27 sites, mostly genes. Our results support may selective pressure driving involved integrating sequence-based functional prediction dN/dS-based detect uncovered convergence populations, probably related thermal conditions.