Extinction is a key issue in the assessment of global biodiversity. However, many extinction rate measures do not account for species that went extinct before they could be discovered. The highly developed island city-state of Singapore has one of the best-documented tropical floras in the world. This presents a unique opportunity to estimate the total rate of local floristic extinctions, after accounting for sampling effort and crypto-extinctions. We collated herbaria records of plant collections in Singapore with the goal of estimating the total extinction rate since 1822. Our database comprises 34224 specimens from 2076 native species, of which 464 species (22%) are estimated to be nationally extinct. Assuming that (1) undiscovered species had the same extinction rates as discovered species, and (2) no undiscovered species remain extant, our classical and Bayesian algorithms estimated that, respectively, 304 (95% confidence interval [213, 414]) and 412 (95% credible interval [313, 534]) additional species went extinct before they could be discovered, giving total extinction rates of 32% and 35% (overall range 30-38%). We detected violations of the model's two assumptions that will cause our extinction estimates, particularly the absolute numbers, to be biased downwards. For this reason, our estimates should be treated as lower bounds. Our numbers illustrate the possible magnitudes of local plant species loss that can be expected in the tropics as development continues. Article impact statement: The number of species that went extinct before they could be discovered can be estimated from museum records. This article is protected by copyright. All rights reserved.

中文翻译：

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新加坡已发现和未发现植物的灭绝率

灭绝是全球生物多样性评估中的一个关键问题。然而，许多灭绝率的衡量标准并没有考虑到在被发现之前就已经灭绝的物种。高度发达的新加坡岛国拥有世界上记录最完整的热带植物群之一。在考虑了采样工作和加密灭绝之后，这提供了一个独特的机会来估计当地植物群灭绝的总速率。我们整理了新加坡植物收藏的标本馆记录，目的是估计自 1822 年以来的总灭绝率。我们的数据库包含来自 2076 个本地物种的 34224 个标本，其中 464 个物种 (22%) 估计已在全国灭绝。假设 (1) 未被发现的物种与已发现的物种具有相同的灭绝率，以及 (2) 没有未被发现的物种仍然存在，我们的经典算法和贝叶斯算法估计，分别有 304 个（95% 置信区间 [213, 414]）和 412 个（95% 可信区间 [313, 534]）其他物种在被发现之前就灭绝了，总灭绝率为32% 和 35%（总体范围 30-38%）。我们检测到违反模型的两个假设，这将导致我们的灭绝估计，特别是绝对数字，向下偏差。出于这个原因，我们的估计应该被视为下限。我们的数字说明了随着发展的继续，热带地区可以预期的当地植物物种损失的可能程度。文章影响说明：可以从博物馆记录中估计在发现之前就已经灭绝的物种数量。本文受版权保护。版权所有。