Meeting Abstract
An organism’s ability to integrate transient environmental cues experienced during development into molecular and physiological responses forms the basis for adaptive shifts in phenotypic trajectories. During temperature-dependent sex determination (TSD), thermal cues during discrete periods of development coordinate molecular changes that ultimately establish sexual fates and contribute to patterns of inter- and intrasexual variation. How these mechanisms interface with the dynamic thermal environments in nature remains largely unknown. For example, ~70% of American alligator nests exhibit both male- and female-promoting temperatures during the thermosensitive period, often within the span of a daily thermal fluctuation. Here, we investigate how these opposing environmental cues are integrated into sexually dimorphic transcriptional programs across fine temporal scales. Alligator embryos were exposed to fluctuating temperatures based on empirically-derived nest thermal profiles and sampled over the course of a daily thermal fluctuation. Post-transcriptional alternative splicing of epigenetic modifier genes operating upstream in the sex-determining cascade respond rapidly to thermal fluctuations, whereas transcriptional changes of downstream effector genes occur on a delayed timescale. Together our findings reveal how the basic mechanisms of TSD operate in an ecologically relevant context and suggest a hierarchical model in which temperature-sensitive alternative splicing incrementally influences the epigenetic landscape to affect the transcriptional activity of key sex-determining genes.
