The University of Queensland, School of Biological Sciences, St Lucia 4072, QLD, Australia.
Conserv Biol. 2012 Feb;26(1):57-67. doi: 10.1111/j.1523-1739.2011.01797.x. Epub 2011 Dec 2.
For species with five or more sightings, quantitative techniques exist to test whether a species is extinct on the basis of distribution of sightings. However, 70% of purportedly extinct mammals are known from fewer than five sightings, and such models do not include some important indicators of the likelihood of extinction such as threats, biological traits, search effort, and demography. Previously, we developed a quantitative method that we based on species' traits in which we used Cox proportional hazards regression to calculate the probability of rediscovery of species regarded as extinct. Here, we used two versions of the Cox regression model to determine the probability of extinction in purportedly extinct mammals and compared the results of these two models with those of stationary Poisson, nonparametric, and Weibull sighting-distribution models. For mammals with five or more sightings, the stationary Poisson model categorized all but two critically endangered (flagged as possibly extinct) species in our data set as extinct, and results with this model were consistent with current categories of the International Union for the Conservation of Nature. The scores of probability of rediscovery for individual species in one version of our Cox regression model were correlated with scores assigned by the stationary Poisson model. Thus, we used this Cox regression model to determine the probability of extinction of mammals with sparse records. On the basis of the Cox regression model, the most likely mammals to be rediscovered were the Montane monkey-faced bat (Pteralopex pulchra), Armenian myotis (Myotis hajastanicus), Alcorn's pocket gopher (Pappogeomys alcorni), and Wimmer's shrew (Crocidura wimmeri). The Cox model categorized two species that have recently disappeared as extinct: the baiji (Lipotes vexillifer) and the Christmas Island pipistrelle (Pipistrellus murrayi). Our new method can be used to test whether species with few records or recent last-sighting dates are likely to be extinct.
对于有五个或更多目击记录的物种，可以使用定量技术来根据目击记录的分布来检验一个物种是否灭绝。然而，70%的所谓灭绝哺乳动物只有不到五次的目击记录，并且这些模型没有包括一些重要的灭绝指标，如威胁、生物特征、搜索努力和种群动态。以前，我们开发了一种定量方法，该方法基于物种的特征，我们使用 Cox 比例风险回归来计算被认为灭绝的物种重新发现的概率。在这里，我们使用了两种 Cox 回归模型来确定所谓灭绝哺乳动物的灭绝概率，并将这两种模型的结果与固定泊松、非参数和 Weibull 目击分布模型的结果进行了比较。对于有五个或更多目击记录的哺乳动物，固定泊松模型将我们数据集中除了两种极危（被标记为可能灭绝）物种之外的所有物种都归类为灭绝，并且该模型的结果与国际自然保护联盟目前的分类一致。我们的 Cox 回归模型的一个版本中，个体物种重新发现概率的得分与固定泊松模型分配的得分相关。因此，我们使用这个 Cox 回归模型来确定记录稀疏的哺乳动物灭绝的概率。基于 Cox 回归模型，最有可能被重新发现的哺乳动物是山地猴面蝠（Pteralopex pulchra）、亚美尼亚蝙蝠（Myotis hajastanicus）、阿尔科恩口袋地鼠（Pappogeomys alcorni）和威默氏鼩鼱（Crocidura wimmeri）。Cox 模型将最近消失的两个物种归类为灭绝：白暨豚（Lipotes vexillifer）和圣诞岛蝙蝠（Pipistrellus murrayi）。我们的新方法可以用于检验记录很少或最近最后目击日期的物种是否有可能灭绝。
