Gene expression underlying variation in survival skills of red drum larvae (Sciaenops ocellatus).

Mortality rates of marine fish larvae are incredibly high and can determine year-class strength. The major causes of larval mortality are predation and starvation, and the performance of larvae in survival skills that can mitigate this mortality (predator evasion, foraging) varies among individuals and cohorts, but the causes of that variation are not known. Transcriptomics can link gene expression variation to phenotypic variation at the whole-system level to investigate the molecular basis of behavioral variation. We used tag-based RNA-sequencing (TagSeq) to examine the molecular basis of variation in predator evasion and routine swimming (trait related to foraging efficiency) in larval red drum, Sciaenops ocellatus. We looked for functional gene networks in which inter-individual variation would explain variation in larval behavioral performance. We identified co-expressed gene groups ("modules") associated with predator evasion traits and found enrichment of motor, neural, and energy metabolism pathways. These functional associations and pattern of correlations between modules and traits suggest that energy availability and allocation were responsible for the magnitude of startle responses, while differential neural and motor activation were associated with differences in response latency. This article is protected by copyright. All rights reserved.