Biologie I, Universität Regensburg, Universitätsstr. 31, Regensburg, 93053, Germany.
BMC Ecol. 2011 Sep 30;11:21. doi: 10.1186/1472-6785-11-21.
Efficient division of reproductive labor is a crucial characteristic of social insects and underlies their ecological and evolutionary success. Despite of the harmonious appearance of insect societies, nestmates may have different interests concerning the partitioning of reproduction among group members. This may lead to conflict about reproductive rights. As yet, few studies have investigated the allocation of reproduction among queens in multi - queen societies ("reproductive skew"). In the ant Leptothorax acervorum, reproductive skew varies considerably among populations. While reproduction is quite equally shared among nestmate queens in most populations from boreal Eurasia (low skew), colonies from populations at the edge of the species' range are characterized by "functional monogyny," i.e., high skew. The proximate mechanisms underlying high skew, in particular how workers influence which queen lays eggs, are not well understood. We investigated the behavior of queens and workers in functionally monogynous colonies of L. acervorum from two mountain ranges in central Spain.
We provide evidence for both queen and worker influence on the outcome of conflict over reproduction in colonies of L. acervorum from Spain. The patterns of queen - queen aggression and worker - queen grooming and feeding after hibernation allowed predicting, which queen later began to lay eggs. In contrast, worker aggression towards queens was not clearly associated with a queen's future reproductive success. Queen - queen and worker - queen aggression differed in quality: queens typically engaged in ritualized dominance behavior, such as antennal boxing, while workers also attacked queens by biting and prolonged pulling on their legs and antennae. In several cases, overt worker aggression led to the expulsion of queens from the nest or their death.
We conclude that queens of L. acervorum from Spain establish rank orders by ritualized dominance interactions, such as antennal boxing. Workers may reinforce these hierarchies by preferentially feeding and grooming high ranking queens and attacking lower ranking queens. Aggressive worker policing may thus stabilize functional monogyny. Optimal skew models predict that high skew in ants is associated with high dispersal costs. In central Spain, L. acervorum is restricted to small patches at higher elevations, which presumably makes dispersal and colony founding difficult. Because of the ecological requirements of L. acervorum and the predicted large impact of global change on central Spain, the functionally monogynous populations of this ant must be considered as threatened.
有效的生殖分工是社会昆虫的一个关键特征，也是它们在生态和进化上取得成功的基础。尽管昆虫社会看起来和谐，但巢内个体可能对群体成员之间的生殖分配有着不同的利益诉求。这可能会导致生殖权利的冲突。尽管如此，很少有研究调查多女王社会中女王之间的生殖分配（生殖倾斜）。在蚂蚁 Leptothorax acervorum 中，生殖倾斜在不同种群之间存在显著差异。在大多数来自欧亚大陆北部的种群中，巢内女王之间的生殖分配相当平等（低倾斜），而在物种分布范围边缘的种群中，生殖分配则呈现“功能单配制”（高倾斜）的特征。高倾斜的潜在机制，特别是工蚁如何影响哪个女王产卵，还没有得到很好的理解。我们调查了来自西班牙两个山脉的功能单配制 L. acervorum 殖民地中女王和工蚁的行为。
我们提供了证据表明，在西班牙的 L. acervorum 殖民地中，女王和工蚁都对生殖冲突的结果产生了影响。冬眠后女王之间的侵略行为、工蚁对女王的梳理和喂养模式，可以预测哪个女王会先开始产卵。相比之下，工蚁对女王的侵略行为与女王未来的生殖成功并没有明显的关联。女王之间和工蚁与女王之间的侵略行为在质量上有所不同：女王通常会进行仪式化的支配行为，如触角拳击，而工蚁则会通过咬和长时间拉扯女王的腿和触角来攻击女王。在一些情况下，明显的工蚁侵略会导致女王被逐出巢穴或死亡。
我们得出结论，来自西班牙的 L. acervorum 女王通过触角拳击等仪式化支配行为来建立等级秩序。工蚁可能通过优先喂养和梳理高等级的女王，并攻击低等级的女王，来加强这些等级制度。因此，工蚁的侵略性监管可能稳定了功能单配制。最优倾斜模型预测，蚂蚁的高倾斜与高扩散成本有关。在西班牙中部，L. acervorum 局限于高海拔的小斑块中，这使得扩散和建立殖民地变得困难。由于 L. acervorum 的生态需求以及对西班牙中部的全球变化的预测的巨大影响，这种蚂蚁的功能单配制种群必须被视为受到威胁。
