Beyond species-level differences: A comprehensive review of intraspecific venom plasticity in spiders.

Spider venoms represent a diverse array of biological cocktails, crucial for predator-prey dynamics and ecological interactions. While differences in venom composition between species (interspecific variation) are well-characterized, the extent and drivers of intraspecific venom plasticity remain a critical, underexplored area. This comprehensive review synthesizes current research on venom variation within species, emphasizing the multifaceted factors that govern this dynamic phenotype. Venom composition, yield, and bioactivity are significantly influenced by both endogenous and exogenous elements. Endogenous factors, mainly sexual dimorphism and ontogenetic stage, often induce profound changes in potency, reflecting sex-specific ecological pressures, predation risk profiles, and shifting reproductive investments. Similarly, exogenous pressures, including seasonal and geographic variations, drive adaptive shifts in venom profiles in response to environmental gradients like temperature and prey availability. Furthermore, recent advances in proteomics and transcriptomics reveal substantial individual-level chemo-diversity, underscoring the complexity of underlying regulatory mechanisms. A paradigm shift is necessary, viewing venom not as a static species characteristic but as a highly plastic, environmentally and genetically mediated trait. Future research must prioritize high-resolution, long-term intra-individual and population-level studies, especially in globally underrepresented taxa and regions, to fully elucidate the ecological and evolutionary forces shaping this crucial biological system.