Masuoka Penny M, Burke Robin, Colaccico Michelle, Razuri Hugo, Hill Dolores, Murrell K Darwin
Department of Preventive Medicine and Biometrics, Uniformed Services, University of the Health Sciences, Bethesda, Maryland 20814, USA.
J Parasitol. 2009 Aug;95(4):829-37. doi: 10.1645/GE-1952.1.
Because of a lack of comprehensive surveys, the geographic distributions of the North American species of encapsulating Trichinella (T. nativa and its variant T6, T. murrelli, and T. spiralis) are poorly characterized in detail. These species are potentially zoonotic; therefore, biogeographic information is critical to monitoring their status and any distribution changes due to climatic and man-made environmental impacts. The maximum entropy (Maxent) program was used to model predicted ranges for these sylvatic Trichinella spp., using a limited number of available location records with confirmed species identifications collected over 55 yr throughout North America. The resulting prediction models were shown to be robust, and the species maps created are presented. The predicted range of T. nativa is primarily north of the 48 degrees - 52 degrees latitudes, overlapping the Tundra, sub-Arctic, and Warm Continental eco-regions. Its sympatric genotypic variant, T6, has a predicted range covering primarily the sub-Arctic and mountainous Temperate Steppe eco-regions, the latter extending below 48 degrees N latitude. In the east, the T6 range includes the Warm Continental and the mountainous Hot Continental eco-regions; the T6 range is also predicted to extend to the Sierra Madre Mountains of Mexico. The most probable range of T. murrelli is centered in the Midwest within the Hot Continental and Prairie eco-regions, with an extension southward to the Subtropical and Tropical/Subtropical Steppe and Desert eco-regions. In the west, it exists in a restricted range characterized as mountainous Mediterranean. The most probable distribution of sylvatic T. spiralis is along the humid east North American coast (Hot Continental south to Subtropical), and along the coast of northwest North America (Marine) to Alaska (subArctic and Tundra). Its most southerly range extends into central Mexico (Tropical/Subtropical Desert). The difference in relative freeze resistance between T. nativa/T6 and T. murrelli undoubtedly accounts for much of this geographic separation. However, the factors responsible for the absence of a more southerly distribution of T. nativa are not obvious, given the overlap in host range with T. murrelli. The maximum July temperature appears to have a significant effect on this distribution pattern. The results of the model building highlight subjects for future research on the biotic and abiotic factors important in determining Trichinella spp. distributions and directions for model validation research.
由于缺乏全面的调查，北美包囊旋毛虫属物种（本地旋毛虫及其变种T6、穆氏旋毛虫和旋毛形线虫）的地理分布细节尚未得到充分描述。这些物种具有潜在的人畜共患性；因此，生物地理信息对于监测它们的现状以及因气候和人为环境影响导致的任何分布变化至关重要。利用最大熵（Maxent）程序，根据在北美55年期间收集的有限数量的已确认物种鉴定的可用位置记录，对这些野生动物旋毛虫物种的预测分布范围进行建模。结果表明，所得预测模型具有稳健性，并呈现了所创建的物种分布图。本地旋毛虫的预测分布范围主要在北纬48度至52度以北，与苔原、亚北极和暖大陆生态区重叠。其同域基因型变种T6的预测分布范围主要覆盖亚北极和山区温带草原生态区，后者延伸至北纬48度以下。在东部，T6的分布范围包括暖大陆和山区热大陆生态区；T6的分布范围预计还将延伸至墨西哥的马德雷山脉。穆氏旋毛虫最可能的分布范围集中在中西部的热大陆和草原生态区内，向南延伸至亚热带和热带/亚热带草原及荒漠生态区。在西部，它存在于一个狭窄的山区地中海特征范围内。野生动物旋毛形线虫最可能的分布区域是沿北美东部湿润海岸（从热大陆向南至亚热带），以及沿北美西北部海岸（海洋性）至阿拉斯加（亚北极和苔原）。其最南端的分布范围延伸至墨西哥中部（热带/亚热带荒漠）。本地旋毛虫/T6和穆氏旋毛虫在相对抗冻性上的差异无疑是造成这种地理隔离的主要原因。然而，考虑到本地旋毛虫与穆氏旋毛虫在宿主范围上的重叠，导致本地旋毛虫没有更向南分布的因素并不明显。7月最高温度似乎对这种分布模式有显著影响。模型构建结果突出了未来关于决定旋毛虫属物种分布的生物和非生物因素研究的主题以及模型验证研究的方向。
