Krupa James J, Hopper Kevin R, Gruber Samuel B, Schmidt Jason M, Harwood James D
Department of Biology University of Kentucky Lexington KY USA.
Biological Sciences Bluegrass Community and Technical College Lexington KY USA.
Ecol Evol. 2020 Mar 30;10(11):4762-4772. doi: 10.1002/ece3.6230. eCollection 2020 Jun.
Plant-animal interactions are diverse and widespread shaping ecology, evolution, and biodiversity of most ecological communities. Carnivorous plants are unusual in that they can be simultaneously engaged with animals in multiple mutualistic and antagonistic interactions including reversed plant-animal interactions where they are the predator. Competition with animals is a potential antagonistic plant-animal interaction unique to carnivorous plants when they and animal predators consume the same prey.The goal of this field study was to test the hypothesis that under natural conditions, sundews and spiders are predators consuming the same prey thus creating an environment where interkingdom competition can occur.Over 12 months, we collected data on 15 dates in the only protected Highland Rim Wet Meadow Ecosystem in Kentucky where sundews, sheet-web spiders, and ground-running spiders co-exist. One each sampling day, we attempted to locate fifteen sites with: (a) both sheet-web spiders and sundews; (b) sundews only; and (c) where neither occurred. Sticky traps were set at each of these sites to determine prey (springtails) activity-density. Ground-running spiders were collected on sampling days. DNA extraction was performed on all spiders to determine which individuals had eaten springtails and comparing this to the density of sundews where the spiders were captured.Sundews and spiders consumed springtails. Springtail activity-densities were lower, the higher the density of sundews. Both sheet-web and ground-running spiders were found less often where sundew densities were high. Sheet-web size was smaller where sundew densities were high.The results of this study suggest that asymmetrical exploitative competition occurs between sundews and spiders. Sundews appear to have a greater negative impact on spiders, where spiders probably have little impact on sundews. In this example of interkingdom competition where the asymmetry should be most extreme, amensalism where one competitor experiences no cost of interaction may be occurring.
植物与动物的相互作用多种多样且广泛存在，塑造着大多数生态群落的生态、进化和生物多样性。食虫植物与众不同，因为它们能同时与动物进行多种互利和拮抗的相互作用，包括颠倒的植物 - 动物相互作用，即它们作为捕食者。与动物的竞争是食虫植物特有的一种潜在拮抗的植物 - 动物相互作用，当它们和动物捕食者捕食相同猎物时就会发生这种情况。这项实地研究的目的是检验以下假设：在自然条件下，茅膏菜和蜘蛛是捕食相同猎物的捕食者，从而创造出一个可能发生跨界竞争的环境。在12个月的时间里，我们在肯塔基州唯一受保护的高地边缘湿草甸生态系统中，于15个日期收集数据，该生态系统中茅膏菜、片网蜘蛛和地行蜘蛛共存。在每个采样日，我们试图找到15个地点，这些地点分别为：（a）既有片网蜘蛛又有茅膏菜；（b）只有茅膏菜；（c）两者都没有的地方。在这些地点的每一处都设置了粘性陷阱，以确定猎物（跳虫）的活动密度。在采样日收集地行蜘蛛。对所有蜘蛛进行DNA提取，以确定哪些个体捕食了跳虫，并将其与捕获蜘蛛地点的茅膏菜密度进行比较。茅膏菜和蜘蛛都捕食跳虫。跳虫的活动密度越低，茅膏菜的密度就越高。在茅膏菜密度高的地方，片网蜘蛛和地行蜘蛛出现的频率都较低。在茅膏菜密度高的地方，片网的尺寸较小。这项研究的结果表明，茅膏菜和蜘蛛之间存在不对称的剥削性竞争。茅膏菜似乎对蜘蛛有更大的负面影响，而蜘蛛可能对茅膏菜几乎没有影响。在这个跨界竞争的例子中，不对称应该是最极端的，可能正在发生一种偏害共生现象，即一个竞争者在相互作用中没有成本。
