Meeting Abstract
In freshwater ecosystems, species typically experience fluctuating diurnal thermal regimes. To determine the life history and transcriptomic response of a mayfly to chronic daily forays into uncomfortably warm temperatures, we first determined chronically stressful temperatures by rearing N. triangulifer for full life cycles under static conditions. We then used this information to create “controls”: daily mean temperature (22°C) oscillating between 19.5°C and 24.5°C and “challenge” treatments: daily mean temperature (26°C) oscillating between 23.5°C and 28.5°C. Life history outcomes did not differ between static and fluctuating temperatures at 22°C, whereas at 26°C, fitness was reduced in oscillating conditions relative to static. RNAseq analysis was conducted on whole larvae sampled at the daily extremes of each variable thermal regime. We found very few genes differentiated (P<0.1, FDR<0.05) within the “control” group, whereas 93 genes were differentiated within the “challenge” group. To assess whether larvae recover from daily forays into challenging temperatures, we compared expression patterns between samples of 23.5°C (cold portion of the “challenge”) and 24.5°C (warm portion of the “control”) and found 334 genes were differentially expressed. Biological function and pathway analyses are currently underway. Our results suggest that larvae do not fully recover from chronic (daily) transient exposures to challenging temperatures.
