Alroy John
Department of Biological Sciences, Macquarie University, NSW 2109, Australia
Proc Natl Acad Sci U S A. 2015 Oct 20;112(42):13003-8. doi: 10.1073/pnas.1508681112. Epub 2015 Oct 5.
There is broad concern that a mass extinction of amphibians and reptiles is now underway. Here I apply an extremely conservative Bayesian method to estimate the number of recent amphibian and squamate extinctions in nine important tropical and subtropical regions. The data stem from a combination of museum collection databases and published site surveys. The method computes an extinction probability for each species by considering its sighting frequency and last sighting date. It infers hardly any extinction when collection dates are randomized and it provides underestimates when artificial extinction events are imposed. The method also appears to be insensitive to trends in sampling; therefore, the counts it provides are absolute minimums. Extinctions or severe population crashes have accumulated steadily since the 1970s and 1980s, and at least 3.1% of frog species have already disappeared. Based on these data and this conservative method, the best estimate of the global grand total is roughly 200 extinctions. Consistent with previous results, frog losses are heavy in Latin America, which has been greatly affected by the pathogenic chytrid fungus Batrachochytrium dendrobatidis. Extinction rates are now four orders-of-magnitude higher than background, and at least another 6.9% of all frog species may be lost within the next century, even if there is no acceleration in the growth of environmental threats.
人们普遍担心两栖动物和爬行动物正在大规模灭绝。在此，我运用一种极为保守的贝叶斯方法来估算九个重要热带和亚热带地区近期两栖动物和有鳞目动物的灭绝数量。数据来源于博物馆馆藏数据库和已发表的实地调查的综合。该方法通过考虑物种的目击频率和最后目击日期来计算每个物种的灭绝概率。当随机化收集日期时，该方法几乎推断不出任何灭绝情况，而当施加人为灭绝事件时，它会给出低估的结果。该方法似乎对抽样趋势也不敏感；因此，它提供的数量是绝对最小值。自20世纪70年代和80年代以来，灭绝或严重的种群崩溃一直在稳步累积，至少3.1%的蛙类物种已经消失。基于这些数据和这种保守方法，全球总数的最佳估计约为200次灭绝。与之前的结果一致，拉丁美洲的蛙类损失惨重，该地区受到致病性壶菌蛙壶菌的严重影响。现在的灭绝速度比背景速度高出四个数量级，即使环境威胁的增长没有加速，在下个世纪所有蛙类物种中至少还有6.9%可能会消失。
