Dipartimento di Zoologia e Genetica Evoluzionistica, Università di Sassari, Sassari, Italy.
PLoS One. 2012;7(3):e33801. doi: 10.1371/journal.pone.0033801. Epub 2012 Mar 23.
Biogeographical and macroecological principles are derived from patterns of distribution in large organisms, whereas microscopic ones have often been considered uninteresting, because of their supposed wide distribution. Here, after reporting the results of an intensive faunistic survey of marine microscopic animals (meiofauna) in Northern Sardinia, we test for the effect of body size, dispersal ability, and habitat features on the patterns of distribution of several groups.
METHODOLOGY/PRINCIPAL FINDINGS: As a dataset we use the results of a workshop held at La Maddalena (Sardinia, Italy) in September 2010, aimed at studying selected taxa of soft-bodied meiofauna (Acoela, Annelida, Gastrotricha, Nemertodermatida, Platyhelminthes and Rotifera), in conjunction with data on the same taxa obtained during a previous workshop hosted at Tjärnö (Western Sweden) in September 2007. Using linear mixed effects models and model averaging while accounting for sampling bias and potential pseudoreplication, we found evidence that: (1) meiofaunal groups with more restricted distribution are the ones with low dispersal potential; (2) meiofaunal groups with higher probability of finding new species for science are the ones with low dispersal potential; (3) the proportion of the global species pool of each meiofaunal group present in each area at the regional scale is negatively related to body size, and positively related to their occurrence in the endobenthic habitat.
CONCLUSION/SIGNIFICANCE: Our macroecological analysis of meiofauna, in the framework of the ubiquity hypothesis for microscopic organisms, indicates that not only body size but mostly dispersal ability and also occurrence in the endobenthic habitat are important correlates of diversity for these understudied animals, with different importance at different spatial scales. Furthermore, since the Western Mediterranean is one of the best-studied areas in the world, the large number of undescribed species (37%) highlights that the census of marine meiofauna is still very far from being complete.
生物地理学和宏观生态学原理源自大型生物的分布模式，而微观生物的分布模式通常被认为无趣，因为它们的分布范围广泛。在这里，在报告了对撒丁岛北部海洋微观动物（小型动物）进行的密集动物区系调查的结果后，我们测试了体型、扩散能力和栖息地特征对几个群体分布模式的影响。
方法/主要发现：作为数据集，我们使用了 2010 年 9 月在拉马达莱纳（意大利撒丁岛）举行的一个研讨会的结果，该研讨会旨在研究软体小型动物区系（Acoela、环节动物、腹毛动物、纽形动物、扁形动物和轮形动物）的选定分类群，以及 2007 年 9 月在特贾诺（瑞典西部）举行的另一个研讨会获得的同一分类群的数据。使用线性混合效应模型和模型平均，同时考虑到采样偏差和潜在的伪重复，我们发现有证据表明：（1）分布范围较窄的小型动物区系群体是扩散潜力较低的群体；（2）发现新科学物种的可能性较高的小型动物区系群体是扩散潜力较低的群体；（3）每个地区的每个小型动物区系群体的全球物种库比例与体型呈负相关，与内生栖息地的出现呈正相关。
结论/意义：我们在微观生物普遍存在假说的框架内对小型动物区系进行的宏观生态学分析表明，不仅体型，而且主要是扩散能力以及内生栖息地的出现，是这些研究不足的动物多样性的重要相关因素，在不同的空间尺度上具有不同的重要性。此外，由于西地中海是世界上研究最好的地区之一，大量未描述的物种（37%）突出表明，海洋小型动物区系的普查仍远未完成。
