Identifying the molecular mechanism and genetic region for habitat specific clock variation in N.discreta PS4B

The 24-hour biological rhythm, or circadian rhythm, has been attributed as a fitness trait in multiple organisms. [1][2][3] To identify how organisms adapted their circadian rhythms to increase their fitness, we used a global population from the Neurospora discreta complex. Under cycling light conditions, North American strains in N. discreta PS4B exhibit no rhythms in their sporulation output. To understand the molecular variation of the oscillator underlying these divergent phenotypes, we analyzed the expression of the key clock protein FREQUENCY and found FRQ levels have a rhythm in constant conditions. Based on our findings, we concluded that the North American strains in the N. discreta PS4B population have decoupled their developmental rhythm from their molecular oscillator to enhance their fitness. Our mathematical model supports the hypothesis that North American strains have increased their fitness by decreasing their coupling coefficient and threshold. In addition, we found the candidate region for habitat specific clock variation (HSCV) occurs on chromosome 3. In an intercontinental F1 population, we observed an opposite allele effect, resulting in strains with the North American phenotype having the African parent allele. To understand the mechanism and components of another oscillator, we used the strain PRD-1, which is hypothesized in the literature to be a key component of the metabolic oscillator. We have observed arrhythmic ATP oscillation in PRD-1 compared to WT strains.M.S.Includes bibliographical referencesby Ryan J. Pachuck