Forbes M R, Alisauskas R T, McLaughlin J D, Cuddington K M
Department of Biology, Carleton University, 1125 Colonel By Drive Ottawa, Ontario, KlS 5B6, Canada e-mail:
Canadian Wildlife Service, Prairie and Northern Wildlife Research Centre, 115 Perimeter Road, Saskatoon, Saskatchewan, S7N OX4, Canada, , , , , , CA.
Oecologia. 1999 Sep;120(4):613-620. doi: 10.1007/s004420050897.
The digestive tracts of 771 lesser snow geese (Chen caerulescens) collected from January to May 1983 from 12 locations (27 samples) were examined for helminth parasites to determine whether parasite species present in wintering geese or in spring migrants occurred independently of each other. Nine helminth species were identified. Seven had mean prevalences >5% and were the focus of this study. Six of those species were waterfowl generalists, one was a goose specialist. Our primary objective was to assess the potential contribution of factors, other than species interactions, in determining patterns of co-occurrence between helminth species. There were few negative relationships between helminth species, regardless of whether presence-absence or abundance data were used. However, some species pairs showed recurrent and significant co-occurrences. There were similar and significant effects of timing of sampling, host gender, and host age, on prevalence and mean abundance of particular species. Co-occurrences were found for those species that showed seasonal declines in prevalence, for those expected to have high colonizing ability based on host age profiles (using abundance data), and for abundant species that may have shared vectors or environmental conditions favorable for transmission. Thus, similarities between parasites in their abundance, transmission biology, and phenology seem sufficient to explain species co-occurrences without invoking other processes such as species interactions.
1983年1月至5月期间，从12个地点（27个样本）采集了771只小雪雁（Chen caerulescens）的消化道，检查其中的蠕虫寄生虫，以确定越冬雁或春季迁徙雁体内的寄生虫种类是否相互独立出现。共鉴定出9种蠕虫。其中7种的平均感染率>5%，是本研究的重点。这些种类中有6种是水鸟常见寄生虫，1种是鹅的特异性寄生虫。我们的主要目标是评估除物种相互作用之外的因素，在确定蠕虫种类共存模式方面的潜在作用。无论使用存在-缺失数据还是丰度数据，蠕虫种类之间的负相关关系都很少。然而，一些种类对显示出反复且显著的共存现象。采样时间、宿主性别和宿主年龄，对特定种类的感染率和平均丰度有类似且显著的影响。对于那些感染率呈季节性下降的种类、基于宿主年龄分布预计具有高定殖能力的种类（使用丰度数据），以及可能共享传播媒介或有利于传播的环境条件的丰富种类，都发现了共存现象。因此，寄生虫在丰度、传播生物学和物候学方面的相似性，似乎足以解释物种共存现象，而无需援引物种相互作用等其他过程。
