The Phenotypic Plasticity of Animal Venoms

Phenotypic plasticity mediates organismal responses to environmental variation and plays an important role in ecological adaptation. Because animal venoms are adaptations that interact directly with the external environment, it seems reasonable to expect that phenotypic plasticity could play a vital role in fine-tuning venoms to changing ecological circumstances. Yet, at first glance, little seems to be known about venom plasticity. A 2017 benchmark paper on scorpions claimed to have found the first evidence of adaptive plasticity in venom composition, but since then no studies that cite this paper have reported other convincing cases of venom plasticity. Adaptive venom plasticity is actually more widespread and more widely studied than is generally recognized. I will argue that this apparent lack of awareness results largely from the historical lack of an integrative venom concept, which has produced a literature that is fractured along taxonomic fault lines and different functional categories of venom. Here I synthesize the disconnected literature on venom plasticity to reveal that our knowledge is both deeper and broader than commonly appreciated. I underline the importance of using the phrase “venom plasticity” only for cases of nongenetic, environmentally induced intraspecific venom variation.