Ferrari Céline, Salle Romain, Callemeyn-Torre Nicolas, Jovelin Richard, Cutter Asher D, Braendle Christian
CNRS, IBV, Inserm, Université Côte d'Azur, Nice, France.
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada.
BMC Ecol. 2017 Dec 19;17(1):43. doi: 10.1186/s12898-017-0150-z.
The drivers of species co-existence in local communities are especially enigmatic for assemblages of morphologically cryptic species. Here we characterize the colonization dynamics and abundance of nine species of Caenorhabditis nematodes in neotropical French Guiana, the most speciose known assemblage of this genus, with resource use overlap and notoriously similar external morphology despite deep genomic divergence.
To characterize the dynamics and specificity of colonization and exploitation of ephemeral resource patches, we conducted manipulative field experiments and the largest sampling effort to date for Caenorhabditis outside of Europe. This effort provides the first in-depth quantitative analysis of substrate specificity for Caenorhabditis in natural, unperturbed habitats.
We amassed a total of 626 strain isolates from nine species of Caenorhabditis among 2865 substrate samples. With the two new species described here (C. astrocarya and C. dolens), we estimate that our sampling procedures will discover few additional species of these microbivorous animals in this tropical rainforest system. We demonstrate experimentally that the two most prevalent species (C. nouraguensis and C. tropicalis) rapidly colonize fresh resource patches, whereas at least one rarer species shows specialist micro-habitat fidelity.
Despite the potential to colonize rapidly, these ephemeral patchy resources of rotting fruits and flowers are likely to often remain uncolonized by Caenorhabditis prior to their complete decay, implying dispersal-limited resource exploitation. We hypothesize that a combination of rapid colonization, high ephemerality of resource patches, and species heterogeneity in degree of specialization on micro-habitats and life histories enables a dynamic co-existence of so many morphologically cryptic species of Caenorhabditis.
对于形态隐秘的物种组合而言，当地群落中物种共存的驱动因素尤其难以捉摸。在此，我们描述了新热带法属圭亚那地区九种秀丽隐杆线虫的定殖动态和丰度，该地区是已知该属物种最为丰富的组合，尽管基因组差异很大，但这些线虫存在资源利用重叠且外部形态极为相似。
为了描述对短暂资源斑块的定殖和利用的动态及特异性，我们进行了操控性野外实验，并开展了迄今为止欧洲以外地区针对秀丽隐杆线虫的最大规模采样工作。这项工作首次对自然、未受干扰栖息地中秀丽隐杆线虫的底物特异性进行了深入定量分析。
我们从2865个底物样本中总共收集到了来自九种秀丽隐杆线虫的626个菌株分离物。加上此处描述的两个新物种（星果秀丽隐杆线虫和多伦斯秀丽隐杆线虫），我们估计我们的采样程序在这个热带雨林系统中发现这些食微生物动物的新物种的可能性很小。我们通过实验证明，两种最常见的物种（诺拉圭秀丽隐杆线虫和热带秀丽隐杆线虫）能迅速定殖新鲜资源斑块，而至少有一种较罕见的物种表现出对特定微生境的忠诚度。
尽管有迅速定殖的潜力，但这些腐烂果实和花朵的短暂斑块状资源在完全腐烂之前很可能常常未被秀丽隐杆线虫定殖，这意味着资源利用受扩散限制。我们推测，快速定殖、资源斑块的高短暂性以及物种在微生境专业化程度和生活史方面的异质性共同作用，使得众多形态隐秘的秀丽隐杆线虫物种能够动态共存。
