Human-driven increases in global mean temperatures are associated with concomitant increases in thermal variability. Yet, few studies have explored the impacts of thermal variability on fitness-related traits, limiting our ability to predict how organisms will respond to dynamic thermal changes. Among the myriad organismal responses to thermal variability, one of the most proximate to fitness—and, thus, a population's ability to persist—is reproduction. Here, we examine how a model freshwater fish ( Danio rerio ) responds to diel thermal fluctuations that span the species's viable developmental range of temperatures. We specifically investigate reproductive performance metrics including spawning success, fecundity, egg provisioning and sperm concentration. Notably, we apply thermal variability treatments during two ontogenetic timepoints to disentangle the relative effects of developmental plasticity and reversible acclimation. We found evidence of direct, negative effects of thermal variability during later ontogenetic stages on reproductive performance metrics. We also found complex interactive effects of early and late-life exposure to thermal variability, with evidence of beneficial acclimation of spawning success and modification of the relationship between fecundity and egg provisioning. Our findings illuminate the plastic life-history modifications that fish may undergo as their thermal environments become increasingly variable.

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to changes in PaCO 2 between 27-50mmHg remains intact during propofol anaesthesia in healthy individuals. Our absolute CBF values are similar to those previously reported during fixed dose propofol anaesthesia but are lower than those we haye recorded during propofol-N20 anaesthesia ~,z. Similarly, the slope of CBF-PaCO 2 relationship is less than during propofol-N20 anaesthesia. These differences may be explained by either the c e r e b r o v a s o d i l a t i n g e f f e c t of N20 or the quantity of propofol used. During hypocapnia, CBF was low, but there were no changes clinically or in the evoked potentials to suggest ischaemia. Propofol may therefore reduce the CBF threshold for cerebral isohaemia as assessed by evoked potentials.