Kehr Arturo I, Manly Bryan F J, Hamann Monika I
CECOAL-CONICET, C.C. 140, (3400) Corrientes, Argentina, Argentina.
Department of Mathematics and Statistics, University of Otago, P.O. Box 56, Dunedin, New Zealand, New Zealand.
Oecologia. 2000 Dec;125(4):549-558. doi: 10.1007/s004420000480. Epub 2000 Dec 1.
The need for studies on helminth communities of South American amphibians was addressed by examining changes in composition and population dynamics of the helminth component and infracommunities in the frog Lysapsus limellus Cope, 1862, from 1994 to 1996. Two pond types were considered, one permanent and one semipermanent. The main goals of this study were (1) to investigate the relationships between pond type, season, study time, frog body size, and frog sex and the presence-absence and counts of helminth parasite species in the frog host, L. limellus, and (2) to examine the co-occurrence of the different parasite species in the frog host in terms of the structure, assembly, and dynamics of the helminth infracommunity. Parasite presence and absence were analyzed using logistic regression and parasite counts were analyzed using log-linear modeling. To examine the association between parasite species, a principal components analysis was carried out on the correlation matrix for the counts. The pattern of co-occurrences was also examined through a randomization test. The main results were as follows: (1) five parasite species were found in the infracommunity; (2) the pond type and the host size class were the principal factors related to the presence and absence of parasites for the three dominant species, while the year of study and the host sex were only important for one of the species; (3) for the parasite counts, many more factors were significant, with body size class and pond type always important factors for the three core species of the infracommunity, with season, year of study, and sex also sometimes important, and (4) strong associations were observed between some helminth species of the host from the permanent pond, but the same species did not co-occur in frogs in the semipermanent pond. The life histories of the five species can be considered as opportunistic or "r strategists."
通过研究1862年命名的利氏雨蛙（Lysapsus limellus Cope）体内蠕虫组成和种群动态以及群落内区的变化，探讨了对南美两栖动物蠕虫群落进行研究的必要性。研究考虑了两种类型的池塘，一种是永久性池塘，另一种是半永久性池塘。本研究的主要目标是：（1）调查池塘类型、季节、研究时间、蛙体大小和蛙的性别与蛙宿主利氏雨蛙体内蠕虫寄生虫物种的有无及数量之间的关系；（2）从蠕虫群落内区的结构、聚集和动态方面，研究不同寄生虫物种在蛙宿主中的共存情况。使用逻辑回归分析寄生虫的有无，使用对数线性模型分析寄生虫数量。为了研究寄生虫物种之间的关联，对数量的相关矩阵进行了主成分分析。还通过随机化检验研究了共存模式。主要结果如下：（1）在群落内区发现了五种寄生虫物种；（2）池塘类型和宿主大小类别是与三种优势物种寄生虫的有无相关的主要因素，而研究年份和宿主性别仅对其中一种物种重要；（3）对于寄生虫数量，更多因素具有显著性，宿主大小类别和池塘类型始终是群落内区三种核心物种的重要因素，季节、研究年份和性别有时也很重要；（4）在永久性池塘宿主的一些蠕虫物种之间观察到强烈关联，但在半永久性池塘的蛙中，相同物种并未共存。这五个物种的生活史可被视为机会主义者或“r策略者”。
