The genomic basis of circadian and circalunar timing adaptations in a midge

• Published in: Nature (London) Vol. 540; no. 7631; pp. 69 - 73
• Main Authors: Kaiser, Tobias S, Poehn, Birgit, Szkiba, David, Preussner, Marco, Sedlazeck, Fritz J, Zrim, Alexander, Neumann, Tobias, Nguyen, Lam-Tung, Betancourt, Andrea J, Hummel, Thomas, Vogel, Heiko, Dorner, Silke, Heyd, Florian, von Haeseler, Arndt, Tessmar-Raible, Kristin
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.12.2016; Nature Publishing Group UK
• Subjects: Acclimatization - genetics; Adaptation; Alternative Splicing - genetics; Animals; Biological clocks; Calcium-Calmodulin-Dependent Protein Kinase Type 2 - genetics; Calcium-Calmodulin-Dependent Protein Kinase Type 2 - metabolism; Chironomidae - classification; Chironomidae - genetics; Chironomidae - physiology; Chironomids; Chromosomes; Circadian Clocks - genetics; Circadian rhythm; Circadian Rhythm - genetics; Circadian rhythms; CLOCK Proteins - genetics; Drosophila melanogaster - enzymology; Drosophila melanogaster - genetics; Gene mapping; Genes; Genetic aspects; Genetic Association Studies; Genetic diversity; Genetic Variation; Genome, Insect - genetics; Genomes; Genomics; Male; Moon; Phenotype; Physiological adaptation; Physiological aspects; Proteins; Quantitative Trait Loci - genetics; Reproduction - genetics; Reproduction - physiology; Species Specificity; Studies; Tidal Waves; Time Factors; Transcription, Genetic
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature20151

Organisms use endogenous clocks to anticipate regular environmental cycles, such as days and tides. Natural variants resulting in differently timed behaviour or physiology, known as chronotypes in humans, have not been well characterized at the molecular level. We sequenced the genome of Clunio marinus, a marine midge whose reproduction is timed by circadian and circalunar clocks. Midges from different locations show strain-specific genetic timing adaptations. We examined genetic variation in five C. marinus strains from different locations and mapped quantitative trait loci for circalunar and circadian chronotypes. The region most strongly associated with circadian chronotypes generates strain-specific differences in the abundance of calcium/calmodulin-dependent kinase II.1 (CaMKII.1) splice variants. As equivalent variants were shown to alter CaMKII activity in Drosophila melanogaster, and C. marinus (Cma)-CaMKII.1 increases the transcriptional activity of the dimer of the circadian proteins Cma-CLOCK and Cma-CYCLE, we suggest that modulation of alternative splicing is a mechanism for natural adaptation in circadian timing.