Yusah Kalsum M, Foster William A, Reynolds Glen, Fayle Tom M
Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia.
Department of Zoology, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom.
PeerJ. 2018 Jan 30;6:e4231. doi: 10.7717/peerj.4231. eCollection 2018.
Competitive interactions in biological communities can be thought of as giving rise to "assembly rules" that dictate the species that are able to co-exist. Ant communities in tropical canopies often display a particular pattern, an "ant mosaic", in which competition between dominant ant species results in a patchwork of mutually exclusive territories. Although ant mosaics have been well-documented in plantation landscapes, their presence in pristine tropical forests remained contentious until recently. Here we assess presence of ant mosaics in a hitherto under-investigated forest stratum, the emergent trees of the high canopy in primary tropical rain forest, and explore how the strength of any ant mosaics is affected by spatial scale, time of day, and sampling method.
To test whether these factors might impact the detection of ant mosaics in pristine habitats, we sampled ant communities from emergent trees, which rise above the highest canopy layers in lowland dipterocarp rain forests in North Borneo (38.8-60.2 m), using both baiting and insecticide fogging. Critically, we restricted sampling to only the canopy of each focal tree. For baiting, we carried out sampling during both the day and the night. We used null models of species co-occurrence to assess patterns of segregation at within-tree and between-tree scales.
The numerically dominant ant species on the emergent trees sampled formed a diverse community, with differences in the identity of dominant species between times of day and sampling methods. Between trees, we found patterns of ant species segregation consistent with the existence of ant mosaics using both methods. Within trees, fogged ants were segregated, while baited ants were segregated only at night.
We conclude that ant mosaics are present within the emergent trees of the high canopy of tropical rain forest in Malaysian Borneo, and that sampling technique, spatial scale, and time of day interact to determine observed patterns of segregation. Restricting sampling to only emergent trees reveals segregatory patterns not observed in ground-based studies, confirming previous observations of stronger segregation with increasing height in the canopy.
生物群落中的竞争相互作用可被视为产生了“组装规则”，这些规则决定了能够共存的物种。热带树冠层中的蚂蚁群落通常呈现出一种特殊模式，即“蚂蚁镶嵌”，其中优势蚂蚁物种之间的竞争导致了相互排斥领地的拼凑分布。尽管蚂蚁镶嵌在人工林景观中已有充分记录，但直到最近，它们在原始热带森林中的存在仍存在争议。在此，我们评估了迄今为止研究较少的森林层次——原始热带雨林高树冠层中的突出树木上蚂蚁镶嵌的存在情况，并探讨了任何蚂蚁镶嵌的强度如何受到空间尺度、一天中的时间以及采样方法的影响。
为了测试这些因素是否可能影响在原始栖息地中对蚂蚁镶嵌的检测，我们从北婆罗洲低地龙脑香雨林中高于最高树冠层（38.8 - 60.2米）的突出树木上采集蚂蚁群落，采用诱饵法和杀虫剂喷雾法。至关重要的是，我们将采样仅限制在每棵目标树的树冠层。对于诱饵法，我们在白天和夜晚都进行了采样。我们使用物种共现的零模型来评估树内和树间尺度上的隔离模式。
在所采样的突出树木上，数量上占优势的蚂蚁物种形成了一个多样化的群落，优势物种的身份在一天中的不同时间和采样方法之间存在差异。在树与树之间，我们使用两种方法都发现了与蚂蚁镶嵌存在相一致的蚂蚁物种隔离模式。在树内，喷雾采集的蚂蚁是隔离的，而诱饵采集的蚂蚁仅在夜间是隔离的。
我们得出结论，在马来西亚婆罗洲热带雨林高树冠层的突出树木中存在蚂蚁镶嵌，并且采样技术、空间尺度和一天中的时间相互作用，以确定观察到的隔离模式。将采样仅限制在突出树木上揭示了在地面研究中未观察到的隔离模式，证实了先前关于随着树冠层高度增加隔离更强的观察结果。
