PDF(Pubmed)
Abstract：
Documenting changes in the distribution and abundance of a given taxon requires historical data. In the absence of long-term monitoring data collected throughout the range of a taxon, conservation biologists often rely on preserved museum specimens to determine the past or present, putative geographic distribution. Distributional data for the Houston Toad (Anaxyrus houstonensis) has consistently been confounded by similarities with a sympatric congener, the Dwarf American Toad (A. americanus charlesmithi), both in monitoring data derived from chorusing surveys, and in historical data via museum specimens. In this case, misidentification can have unintended impacts on conservation efforts, where the Houston Toad is federally endangered, and the Dwarf American Toad is of least concern. Previously published reports have compared these two taxon on the basis of their male advertisement call and morphological appearance, often with the goal of using these characters to substantiate their taxonomic status prior to the advent of DNA sequencing technology. However, numerous studies report findings that contradict one another, and no consensus on the true differences or similarities can be drawn. Here, we use contemporary recordings of wild populations of each taxon to test for quantifiable differences in male advertisement call. Additionally, we quantitatively examine a subset of vouchered museum specimens representing each taxon to test previously reported differentiating morphometric characters used to distinguish among other Bufonids of East-Central Texas, USA. Finally, we assemble and qualitatively evaluate a database of photographs representing catalogued museum vouchers for each taxon to determine if their previously documented historic ranges may be larger than are currently accepted. Our findings reveal quantifiable differences between two allopatric congeners with respect to their male advertisement call, whereas we found similarities among their detailed morphology. Additionally, we report on the existence of additional, historically overlooked, museum records for the Houston Toad in the context of its putative historic range, and discuss errors associated with the curation of these specimens whose identity and nomenclature have not been consistent through time. These results bookend decades of disagreement regarding the morphology, voice, and historic distribution of these taxa, and alert practitioners of conservation efforts for the Houston Toad to previously unreported locations of occurrence.
摘要：
记录给定分类单元的分布和丰度的变化需要历史数据。在没有收集整个分类单元范围内的长期监测数据的情况下，保护生物学家通常依靠保存的博物馆标本来确定过去或现在，假定的地理分布。休斯顿蟾蜍（Anaxyrushoustonensis）的分布数据一直被与同胞同类物的相似性所混淆，矮人美国蟾蜍（A.Americanuscharlesmithi)，无论是在监控来自合唱调查的数据中，以及通过博物馆标本获得的历史数据。在这种情况下,错误识别可能会对保护工作产生意想不到的影响，休斯顿蟾蜍濒临灭绝，矮美国蟾蜍是最不关心的。先前发表的报告根据其男性广告称呼和形态外观对这两个分类单元进行了比较，通常目的是在DNA测序技术出现之前使用这些字符来证实其分类地位。然而,许多研究报告的发现相互矛盾，无法就真正的差异或相似之处达成共识。这里,我们使用每个分类单元的野生种群的当代记录来测试男性广告呼叫的可量化差异。此外,我们定量检查了代表每个分类单元的有证博物馆标本的子集，以测试先前报告的用于区分德克萨斯州中东部其他Bufonids的形态计量学特征，美国。最后,我们收集并定性评估一个代表每个分类单元的博物馆分类券的照片数据库，以确定其先前记录的历史范围是否可能大于目前接受的范围。我们的发现揭示了两种异形同源物之间在男性广告呼叫方面的可量化差异，而我们发现它们的详细形态相似。此外,我们报告了额外的存在，历史上被忽视的，休斯顿蟾蜍在其假定的历史范围内的博物馆记录，并讨论与这些标本的鉴定和命名法随着时间的推移并不一致相关的错误。这些结果结束了几十年关于形态学的分歧，声音,这些类群的历史分布，并提醒从业人员注意休斯顿蟾蜍的保护工作，以确保以前未报告的发生地点。
