Farrell Maxwell J, Stephens Patrick R, Berrang-Ford Lea, Gittleman John L, Davies T Jonathan
Biology Department, McGill University, 1205 Docteur Penfield, Montreal, QC, H3A 1B1, Canada.
Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA.
J Anim Ecol. 2015 Jul;84(4):978-84. doi: 10.1111/1365-2656.12342. Epub 2015 Mar 4.
Host extinction can alter disease transmission dynamics, influence parasite extinction and ultimately change the nature of host-parasite systems. While theory predicts that single-host parasites are among the parasite species most susceptible to extinction following declines in their hosts, documented parasite extinctions are rare. Using a comparative approach, we investigate how the richness of single-host and multi-host parasites is influenced by extinction risk among ungulate and carnivore hosts. Host-parasite associations for free-living carnivores (order Carnivora) and terrestrial ungulates (orders Perissodactyla + Cetartiodactyla minus cetaceans) were merged with host trait data and IUCN Red List status to explore the distribution of single-host and multi-host parasites among threatened and non-threatened hosts. We find that threatened ungulates harbour a higher proportion of single-host parasites compared to non-threatened ungulates, which is explained by decreases in the richness of multi-host parasites. However, among carnivores threat status is not a significant predictor of the proportion of single-host parasites, or the richness of single-host or multi-host parasites. The loss of multi-host parasites from threatened ungulates may be explained by decreased cross-species contact as hosts decline and habitats become fragmented. Among carnivores, threat status may not be important in predicting patterns of parasite specificity because host decline results in equal losses of both single-host parasites and multi-host parasites through reduction in average population density and frequency of cross-species contact. Our results contrast with current models of parasite coextinction and highlight the need for updated theories that are applicable across host groups and account for both inter- and intraspecific contact.
宿主灭绝会改变疾病传播动态，影响寄生虫灭绝，并最终改变宿主 - 寄生虫系统的性质。虽然理论预测单宿主寄生虫是宿主数量下降后最易灭绝的寄生虫物种之一，但有记录的寄生虫灭绝情况却很罕见。我们采用比较方法，研究有蹄类动物和食肉动物宿主的灭绝风险如何影响单宿主和多宿主寄生虫的丰富度。将自由生活的食肉动物（食肉目）和陆生有蹄类动物（奇蹄目 + 偶蹄目减去鲸类）的宿主 - 寄生虫关联与宿主特征数据和世界自然保护联盟红色名录状态相结合，以探索单宿主和多宿主寄生虫在受威胁和未受威胁宿主中的分布情况。我们发现，与未受威胁的有蹄类动物相比，受威胁的有蹄类动物携带单宿主寄生虫的比例更高，这是由于多宿主寄生虫丰富度的下降所致。然而，在食肉动物中，威胁状态并不是单宿主寄生虫比例、单宿主或多宿主寄生虫丰富度的重要预测指标。受威胁有蹄类动物多宿主寄生虫的减少可能是由于宿主数量下降和栖息地破碎化导致跨物种接触减少所致。在食肉动物中，威胁状态在预测寄生虫特异性模式方面可能并不重要，因为宿主数量下降会通过平均种群密度降低和跨物种接触频率减少导致单宿主寄生虫和多宿主寄生虫数量同等减少。我们的结果与当前的寄生虫共同灭绝模型形成对比，并强调需要更新适用于不同宿主群体并考虑种间和种内接触的理论。
