COS 241-2 - CANCELLED - Developmental plasticity and acclimation of reproduction under thermal variability

Background/Question/Methods

Human-driven increases in global mean temperatures are being met with concomitant increases in thermal variability. Yet, few studies have explored the impacts of thermal variability on fitness-related traits in fishes, 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’ viable developmental range of temperatures. We specifically investigate reproductive performance metrics such as fecundity, sperm concentration, egg provisioning, and breeding success. Notably, we apply thermal variability treatments during two ontogenetic timepoints to disentangle the relative effects of developmental plasticity and reversible acclimation.

Results/Conclusions

We found evidence of direct, negative effects of thermal variability during later ontogenetic stages on reproductive performance. We also found complex interactive effects of early and late-life exposure to thermal variability, which greatly improved breeding success, modulated the relationship between fecundity and egg provisioning, and affected within-clutch variation in provisioning. Our findings shed light on the plastic life-history modifications that fish may undergo as their thermal environments become increasingly variable.