Abstract Several small habitat patches typically contain more species than a single large patch of comparable area. This pattern has fueled controversy over reserve design (the SLOSS debate); yet its causes remain poorly understood, limiting discussion of any broader biodiversity implications. Using 44 published faunal metacommunity datasets from fragments, islands and habitat islands, we test four hypotheses to explain differences in species richness (SRd) between several small patches and a single large patch: (i) beta diversity (BD); (ii) evenness of species abundance distributions (EV); (iii) size bias in sampling efficiency (SE); and (iv) taxonomy. We used individual-based null models and confirmatory path analysis to compare direct and indirect support for these non-exclusive hypotheses. Broad taxonomic grouping (invertebrates > birds = non-volant vertebrates) accounted for most of the variation in SRd, while BD, EV and SE had smaller, but comparable, direct effects (standardized coefficients = 0.42, 0.31 and −0.26 respectively). Within a taxonomic group, larger SRd occurred when both BD and EV increase. Although sampling bias probably overstates the difference in SRd, it does not explain the pattern. Beyond reserve design, the SLOSS pattern implies potential principles for managing biodiversity in fragmented landscapes. Whether this pattern should inform conservation requires greater understanding. We confirm beta diversity is the major contributor, but it is mediated by increases and decreases in evenness among small patches. Attention to how sub-division alters relative abundances (e.g., by biotic relaxation or altering competitive outcomes) might help clarify how the SLOSS pattern arises.

中文翻译：

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量化因素以了解为什么几个小斑块比一个大斑块拥有更多的物种

摘要 几个小的栖息地斑块通常比可比较区域的单个大斑块包含更多的物种。这种模式引发了关于储备设计的争议（SLOSS 辩论）；然而其原因仍然知之甚少，限制了对任何更广泛的生物多样性影响的讨论。使用来自碎片、岛屿和栖息地岛屿的 44 个已发布的动物群落元群落数据集，我们测试了四个假设来解释几个小斑块和单个大斑块之间物种丰富度 (SRd) 的差异：(i) β多样性 (BD)；(ii) 物种丰度分布 (EV) 的均匀性；(iii) 抽样效率（SE）的规模偏差；(iv) 分类法。我们使用基于个体的零模型和验证性路径分析来比较对这些非排他性假设的直接和间接支持。广泛的分类群（无脊椎动物 > 鸟类 = 非自由脊椎动物）占 SRd 的大部分变化，而 BD、EV 和 SE 具有较小但可比较的直接影响（标准化系数分别为 0.42、0.31 和 -0.26）。在一个分类组中，当 BD 和 EV 都增加时，会出现更大的 SRd。尽管抽样偏差可能夸大了 SRd 的差异，但它并不能解释这种模式。除了保护区设计之外，SLOSS 模式还暗示了在支离破碎的景观中管理生物多样性的潜在原则。这种模式是否应该为保护提供信息需要更多的理解。我们确认 beta 多样性是主要贡献者，但它是由小块之间均匀度的增加和减少所介导的。注意细分如何改变相对丰度（例如，