Palmer Todd M, Brody Alison K
Center for Population Biology, University of California, Davis, California 95616, USA.
Ecology. 2007 Dec;88(12):3004-11. doi: 10.1890/07-0133.1.
The foundation of many plant-ant mutualisms is ant protection of plants from herbivores in exchange for food and/or shelter. While the role of symbiotic ants in protecting plants from stem- and leaf-feeding herbivores has been intensively studied, the relationship between ant defense and measures of plant fitness has seldom been quantified. We studied ant aggression, damage by herbivores and seed predators, and fruit production among Acacia drepanolobium trees occupied by four different acacia-ant species in an East African savanna. Levels of ant aggression in response to experimental disturbance differed strongly among the four species. All four ant species recruited more strongly to new leaf growth on host plants following disturbance, while recruitment to developing fruits was on average an order of magnitude lower. Host plants occupied by more aggressive ant species suffered significantly less vegetative damage from leaf-feeding insects, stem-boring beetles, and vertebrate browsers than host plants occupied by less aggressive ant species. However, there were no differences among fruiting host plants occupied by different ant species in levels of seed predation by bruchid seed predators. Fruit production on host trees was significantly correlated with tree stem diameter but not with the identity of resident ants. Our results demonstrate that defense of host plants may differ substantially among ant species and between vegetative and reproductive structures and that fruit production is not necessarily correlated with high levels of aggression by resident ants.
许多植物与蚂蚁共生关系的基础是，蚂蚁保护植物免受食草动物侵害，以换取食物和/或庇护所。虽然共生蚂蚁在保护植物免受取食茎和叶的食草动物侵害方面的作用已得到深入研究，但蚂蚁防御与植物适合度指标之间的关系却很少被量化。我们在东非稀树草原研究了四种不同的金合欢蚂蚁所占据的阿拉伯胶树中的蚂蚁攻击性、食草动物和种子捕食者造成的损害以及果实产量。在受到实验干扰时，这四种蚂蚁的攻击性水平差异很大。所有四种蚂蚁在受到干扰后，对宿主植物新叶生长的招募反应都更强，而对发育中的果实的招募平均要低一个数量级。被攻击性更强的蚂蚁物种占据的宿主植物，比起被攻击性较弱的蚂蚁物种占据的宿主植物，遭受取食叶片的昆虫、蛀茎甲虫和脊椎动物啃食造成的营养损害要少得多。然而，不同蚂蚁物种占据的结果宿主植物在豆象种子捕食者造成的种子捕食水平上没有差异。宿主树上的果实产量与树干直径显著相关，但与栖息蚂蚁的种类无关。我们的结果表明，宿主植物的防御在不同蚂蚁物种之间以及营养结构和繁殖结构之间可能有很大差异，而且果实产量不一定与栖息蚂蚁的高攻击性相关。
