Comparative transcriptome analysis to reveal the genes and pathways associated with adaptation strategies in two different populations of Manila clam (Ruditapes philippinarum) under acute temperature challenge

Increasing temperature is causing rapid changes in oceanic environments. Understanding the responses of marine animals to such changes remains a major challenge, yet it is key to predicting future biodiversity loss or gain. In this study, we investigated molecular mechanisms of adaptation to acute temperature change in low and high latitude populations of the Manila clam Ruditapes philippinarum . Using transcriptome analysis, we studied temperature-responsive genes and pathways in clams cultured under acute temperature stress (−1°C and 28°C) and identified an extensive set of genes and pathways that respond to acute temperature stress. Physiological changes at the molecular level were compared to explore potential differences in the response of clams and their adaptation to temperature change and to uncover the underlying mechanisms of resilience or sensitivity to stress conditions in the two clam populations. The enrichment of genes involved in protein processing in the endoplasmic reticulum was integral to the adaptation of clams to stressful conditions. Furthermore, phagosome-related genes and pathways were significantly enriched under acute high temperature stress. The upregulation of xenobiotic metabolism by cytochrome P450 showed a population-specific response in the low-latitude clams under both heat and cold stress but not in the high-latitude clams, whereas genes encoding peroxisomes were upregulated in high-latitude clams under heat stress but not in low-latitude clams. This study provides useful information related to the response of R. philippinarum to temperature stress, which could be helpful for improving the temperature stress resistance of these clams in the aquaculture industry. Our results may also help predict future biodiversity trends under temperature change scenarios. • Physiological changes at the molecular level were compared to explore the potential difference between two clam populations under stress. • Elucidated different pathways and genes differentially expressed under acute temperature increase and decrease stress. • Provided data on the sensitivities of two different populations of manila clam in two different temperature stress.