The small-island effect (SIE) is an important pattern in the research fields of island biogeography and biodiversity science. Amphibians and reptiles, while playing important roles in ecosystems, are experiencing global declines. However, to date, no study has explicitly examined the generality and processes underlying the SIE in amphibians and reptiles. Here, we complied 105 global data sets to systematically evaluate the prevalence and underlying factors determining the occurrence of SIEs, area threshold (T) and difference in area threshold (ΔT) between amphibians and reptiles. We applied 27 species–area relationship (SAR) models to the 105 global data sets of amphibians and reptiles to test for the existence of SIEs. We obtained 12 island characteristics, 5 environmental variables, 2 anthropogenic influence variables and 8 species traits that are linked to species survival, which were then tested separately and in combination to examine their roles in determining the occurrence of SIEs, area threshold and ΔT between amphibians and reptiles. We found SIEs in 20 out of 45 (44%) archipelagos for amphibians and 35 out of 60 (58%) archipelagos for reptiles. The occurrence of SIEs was affected by the number of islands, mean annual precipitation and minimum range size for amphibians, whereas only by the number of islands for reptiles. Area thresholds of amphibians were significantly higher than those of reptiles within the same true island system. Area thresholds were affected by mean island area and mean annual temperature for amphibians, whereas by mean island area, temperature seasonality and minimum range size for reptiles. ΔT was affected only by island type. Our study demonstrates that the determinants of the occurrence of SIEs and area thresholds comprised both extrinsic and intrinsic variables but differed substantially between amphibians and reptiles.

中文翻译：

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两栖动物和爬行动物小岛效应的全球综合

小岛效应（SIE）是岛屿生物地理学和生物多样性科学研究领域的一个重要模式。两栖动物和爬行动物虽然在生态系统中发挥着重要作用，但正在经历全球衰退。然而，迄今为止，还没有研究明确检查两栖动物和爬行动物 SIE 的普遍性和过程。在这里，我们编制了 105 个全球数据集，以系统地评估决定 SIE 发生的流行率和潜在因素、面积阈值 ( T ) 和面积阈值差异 (Δ T) 介于两栖动物和爬行动物之间。我们将 27 个物种-区域关系 (SAR) 模型应用于 105 个两栖动物和爬行动物的全球数据集，以测试 SIE 的存在。我们获得了与物种生存相关的 12 个岛屿特征、5 个环境变量、2 个人为影响变量和 8 个物种特征，然后单独和组合测试它们在确定 SIE 发生、面积阈值和ΔT 中的作用介于两栖动物和爬行动物之间。我们在两栖动物的 45 个 (44%) 群岛中的 20 个和爬行动物的 60 个 (58%) 群岛中的 35 个中发现了 SIE。SIEs的发生受岛屿数量、年平均降水量和两栖动物最小活动范围的影响，而爬行动物仅受岛屿数量的影响。在同一真岛系统中，两栖动物的面积阈值明显高于爬行动物。面积阈值受两栖动物的平均岛屿面积和年平均温度的影响，而爬行动物的平均岛屿面积、温度季节性和最小范围大小受到影响。Δ Ť仅受岛屿类型的影响。我们的研究表明，SIE 发生的决定因素和面积阈值包括外在和内在变量，但在两栖动物和爬行动物之间存在很大差异。