Barshis, D. J. | Search bioRxiv

bioRxiv2025

Heat-responsive dynamic shifts in alternative splicing of the coral Acropora cervicornis

Climate change has caused drastic declines in corals. As sessile organisms, response to shifting environmental conditions may include changes in gene expression, epigenetic modifications, or the microbiome, but as of yet, a common mechanism of stress response, alternative splicing (AS), has been underexplored in corals. Using short-term acute thermal stress assays, we investigated patterns of AS in the scleractinian coral Acropora cervicornis during response to and a subsequent overnight recovery phase from low (33), medium (35), and high (37) levels of heat stress. We find that 40% of the genomic gene set is subject to AS. Our findings demonstrate conserved and dynamic shifts in splicing profiles during the heat treatment and subsequent recovery phase. AS increased in response to heat stress and was primarily dominated by intron retention in specific classes of transcripts, including those related to splicing regulation itself. While AS returned to baseline levels post-exposure to low heat, AS persisted even after reprieve from higher levels of heat stress. Partial overlap of AS transcripts with differentially expressed genes suggests that AS may represent a distinct and previously underappreciated regulatory mechanism for thermal stress response in corals.

genomics↗

bioRxiv2018

High-frequency temperature variability mirrors fixed differences in thermal limits of the massive coral Porites lobata (Dana, 1846)

Spatial heterogeneity in environmental characteristics can drive adaptive differentiation when contrasting environments exert divergent selection pressures. This environmental and genetic heterogeneity can substantially influence population and community resilience to disturbance events. Here, we investigated corals from the highly variable back reef habitats of Ofu Island in American Samoa that thrive in thermal conditions known to elicit widespread bleaching and mortality elsewhere. To investigate the hypothesis that thermal variability is the driving force shaping previously observed differences in coral tolerance limits in Ofu, specimens of the common Indo-Pacific coral Porites lobata (Dana, 1846) from locations with differing levels of thermal variability were acclimated to low and high thermal variation in controlled common garden experimental aquaria. Overall, there was minimal effect of the acclimation exposure. Corals native to the site with the highest level of daily variability grew fastest, regardless of acclimation treatment. When exposed to lethal thermal stress, corals native to both variable sites contained elevated levels of heat shock proteins and maintained photosynthetic performance for 1-2 days longer than corals from the stable environment. Despite being separated by < 5 km, there was significant genetic differentiation among coral colonies (FST = 0.206, p < 0.0001; nuclear ribosomal DNA), while Symbiodinium phylotypes were all ITS2-type C15. Our study demonstrates consistent signatures of adaptation in growth and stress resistance in corals from naturally thermally variable habitats, emphasizing that existing genetic diversity of corals is an important asset in strategies to protect and manage coral reef ecosystems in the face of global change.\n\nSummary StatementCorals native to highly variable habitats demonstrate greater thermal tolerance than corals from less variable habitats after 36-days of acclimation to thermally stable or variable common garden treatments.

evolutionary biology↗