Curtis Thomas P, Head Ian M, Lunn Mary, Woodcock Stephen, Schloss Patrick D, Sloan William T
School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle NE1 7RU, UK.
Philos Trans R Soc Lond B Biol Sci. 2006 Nov 29;361(1475):2023-37. doi: 10.1098/rstb.2006.1921.
The extent of microbial diversity is an intrinsically fascinating subject of profound practical importance. The term 'diversity' may allude to the number of taxa or species richness as well as their relative abundance. There is uncertainty about both, primarily because sample sizes are too small. Non-parametric diversity estimators make gross underestimates if used with small sample sizes on unevenly distributed communities. One can make richness estimates over many scales using small samples by assuming a species/taxa-abundance distribution. However, no one knows what the underlying taxa-abundance distributions are for bacterial communities. Latterly, diversity has been estimated by fitting data from gene clone libraries and extrapolating from this to taxa-abundance curves to estimate richness. However, since sample sizes are small, we cannot be sure that such samples are representative of the community from which they were drawn. It is however possible to formulate, and calibrate, models that predict the diversity of local communities and of samples drawn from that local community. The calibration of such models suggests that migration rates are small and decrease as the community gets larger. The preliminary predictions of the model are qualitatively consistent with the patterns seen in clone libraries in 'real life'. The validation of this model is also confounded by small sample sizes. However, if such models were properly validated, they could form invaluable tools for the prediction of microbial diversity and a basis for the systematic exploration of microbial diversity on the planet.
微生物多样性的程度是一个本质上引人入胜且具有深远实际重要性的课题。“多样性”一词可能指分类单元的数量或物种丰富度以及它们的相对丰度。两者都存在不确定性，主要是因为样本量太小。如果在分布不均的群落上使用小样本量，非参数多样性估计器会严重低估。通过假设物种/分类单元 - 丰度分布，可以使用小样本在多个尺度上进行丰富度估计。然而，没有人知道细菌群落的潜在分类单元 - 丰度分布是什么。最近，通过拟合基因克隆文库的数据并由此推断分类单元 - 丰度曲线来估计多样性，进而估计丰富度。然而，由于样本量小，我们不能确定这样的样本是否代表了从中抽取样本的群落。然而，有可能制定并校准预测当地群落以及从该当地群落抽取的样本的多样性的模型。这种模型的校准表明迁移率很小，并且随着群落规模的增大而降低。该模型的初步预测在定性上与“现实生活”中克隆文库中看到的模式一致。该模型的验证也因样本量小而受到困扰。然而，如果这样的模型得到适当验证，它们可以成为预测微生物多样性的宝贵工具，并为系统探索地球上的微生物多样性奠定基础。
