Gangur Alex N, Smout Michael, Liddell Michael J, Seymour Jamie E, Wilson David, Northfield Tobin D
Centre for Tropical Environmental and Sustainability Studies, College of Science and Engineering, James Cook University, Cairns, Queensland 4878, Australia
Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute for Tropical Health and Medicine, James Cook University, Cairns, Queensland 4878, Australia.
Proc Biol Sci. 2017 Sep 27;284(1863). doi: 10.1098/rspb.2017.1364.
Animals embedded between trophic levels must simultaneously balance pressures to deter predators and acquire resources. Venomous animals may use venom toxins to mediate both pressures, and thus changes in this balance may alter the composition of venoms. Basic theory suggests that greater exposure to a predator should induce a larger proportion of defensive venom components relative to offensive venom components, while increases in arms races with prey will elicit the reverse. Alternatively, reducing the need for venom expenditure for food acquisition, for example because of an increase in scavenging, may reduce the production of offensive venom components. Here, we investigated changes in scorpion venom composition using a mesocosm experiment where we manipulated scorpions' exposure to a surrogate vertebrate predator and live and dead prey. After six weeks, scorpions exposed to surrogate predators exhibited significantly different venom chemistry compared with naive scorpions. This change included a relative increase in some compounds toxic to vertebrate cells and a relative decrease in some compounds effective against their invertebrate prey. Our findings provide, to our knowledge, the first evidence for adaptive plasticity in venom composition. These changes in venom composition may increase the stability of food webs involving venomous animals.
处于营养级之间的动物必须同时平衡抵御捕食者和获取资源的压力。有毒动物可能会利用毒液毒素来调节这两种压力，因此这种平衡的变化可能会改变毒液的成分。基本理论表明，相对于攻击性毒液成分，更多地接触捕食者应该会导致防御性毒液成分的比例更大，而与猎物的军备竞赛增加则会产生相反的效果。或者，减少获取食物所需的毒液消耗，例如由于食腐行为增加，可能会减少攻击性毒液成分的产生。在这里，我们通过一个中宇宙实验研究了蝎子毒液成分的变化，在这个实验中，我们控制了蝎子接触替代脊椎动物捕食者以及活的和死的猎物的情况。六周后，与未接触过捕食者的蝎子相比，接触替代捕食者的蝎子表现出显著不同的毒液化学组成。这种变化包括对脊椎动物细胞有毒的一些化合物相对增加，以及对其无脊椎动物猎物有效的一些化合物相对减少。据我们所知，我们的研究结果首次为毒液成分的适应性可塑性提供了证据。毒液成分的这些变化可能会增加涉及有毒动物的食物网的稳定性。
