Data from: Asymmetric dispersal and colonization success of Amazonian plant-ants queens

Background: The dispersal ability of queens is central to understanding ant life-history evolution, and plays a fundamental role in ant population and community dynamics, the maintenance of genetic diversity, and the spread of invasive ants. In tropical ecosystems, species from over 40 genera of ants establish colonies in the stems, hollow thorns, or leaf pouches of specialized plants. However, little is known about the relative dispersal ability of queens competing for access to the same host plants. Methodology/Principal Findings: We used empirical data and inverse modeling – a technique developed by plant ecologists to model seed dispersal – to quantify and compare the dispersal kernels of queens from three Amazonian ant species that compete for access to host-plants. We found that the modal colonization distance of queens varied 8-fold, with the generalist ant species (Crematogaster laevis) having a greater modal distance than two specialists (Pheidole minutula, Azteca sp.) that use the same host-plants. However, our results also suggest that queens of Azteca sp. have maximal distances that are four-sixteen times greater than those of its competitors. Conclusions/Significance: We found large differences between ant species in both the modal and maximal distance ant queens disperse to find vacant seedlings used to found new colonies. These differences could result from interspecific differences in queen body size, and hence wing musculature, or because queens differ in their ability to identify potential host plants while in flight. Our results provide support for one of the necessary conditions underlying several of the hypothesized mechanisms promoting coexistence in tropical plant-ants. They also suggest that for some ant species, limited dispersal capability could pose a significant barrier to the rescue of populations in isolated forest fragments. Finally, we demonstrate that inverse models parameterized with field data are an excellent means of quantifying the dispersal of ant queens.

背景：蚁后（queen）的扩散能力是理解蚂蚁生活史演化的核心，同时对蚂蚁种群与群落动态、遗传多样性维持以及入侵蚂蚁的扩散均具有基础性作用。在热带生态系统中，超过40个蚂蚁属的物种会在特化植物的茎干、中空棘刺或叶囊内建立种群。然而，针对竞争同一宿主植物的蚁后间相对扩散能力的研究仍较为匮乏。
研究方法与主要结果：我们借助实测数据与逆向建模（inverse modeling）——一种由植物生态学家开发的用于模拟种子扩散的方法——对三种竞争宿主植物的亚马逊流域蚂蚁物种的蚁后扩散核（dispersal kernels）进行量化与比较。研究发现，蚁后的众数定植距离差异可达8倍：利用相同宿主植物的广食性蚂蚁物种平刺举腹蚁（*Crematogaster laevis*）的众数距离大于两种专食性蚂蚁细足大头蚁（*Pheidole minutula*）、Azteca属物种（*Azteca sp.*）。但我们的研究结果同时显示，Azteca属蚁后的最大扩散距离是其竞争者的4至16倍。
结论与意义：我们发现，不同蚂蚁物种的蚁后在寻找用于建立新种群的空闲幼苗时的众数与最大扩散距离均存在显著差异。这类差异可能源于蚁后体型（进而影响翅部肌肉）的种间差异，或是蚁后在飞行过程中识别潜在宿主植物的能力存在差异。我们的研究结果为若干促进热带伴生蚂蚁共存的假说机制所需的必要条件之一提供了支撑。同时，研究结果也表明，对于部分蚂蚁物种而言，有限的扩散能力可能会成为孤立森林片段中种群拯救的重大障碍。最后，我们证实了以野外数据参数化的逆向建模方法是量化蚁后扩散能力的极佳手段。