Abstract / Summary
Abstract Parasitism is a pervasive threat to animal fitness that can reduce survival and reproduction, yet mechanisms of host resistance and tolerance remain unclear, particularly in amphibians. Here, we investigated skin transcriptomic variation in the Hong Kong newt, Paramesotriton hongkongensis , across three natural populations characterised by high, low and no infestation by the ectoparasitic water mite Hygrobates aloisii . By generating a de novo skin transcriptome and using comparative gene expression analyses, we identified the highest number of differentially expressed genes between the highly infested and non-infested populations (5,508 DEGs), followed by the low-infested and non-infested (1,899) and highly and low-infested populations (1,165). Immune system processes were enriched in both infested populations, consistent with a shared cutaneous immune signature characterised particularly by genes involved in chemokine and cytokine signaling, while the highly infested population showed additional transcriptional patterns associated with wound healing. In contrast, keratin-related genes did not increase progressively with parasite burden, suggesting that epidermal responses may depend on infestation context rather than scale directly with parasite load. Overall, our findings shed light on molecular variations that may be associated with parasitism in wild amphibian populations and provide a foundation for understanding how organisms cope with environmental stress under natural conditions.