van der Wal R, Irvine J, Stien A, Shepherd N, Albon S D
Centre for Ecology & Hydrology; formerly the Institute of Terrestrial Ecology, Banchory Research Station, Hill of Brathens, Glassel, Banchory, AB31 4BY, Scotland, UK e-mail:
Oecologia. 2000 Jul;124(1):19-25. doi: 10.1007/s004420050020.
We tested whether Svalbard reindeer (Rangifer tarandus platyrhynchus) minimise the risk of gastro- intestinal nematode infection by avoiding patches with a high density of faeces. This experiment was performed in preferred summer foraging habitat. The possibility that reindeer assess infection risk on the basis of faecal contamination levels across plant communities was determined by measuring the distribution of faeces in seven plant communities, and nematode developmental success in two plant communities with contrasting soil moisture content. We explored whether variation within individual reindeer in the levels of infection by gastro-intestinal nematodes was related to their diet. Reindeer avoided pastures where faecal contamination was increased, and thereby potentially reduced the risk of becoming infected by Trichostrongyle nematodes. Dung density was inversely related to soil moisture content, with high densities of faeces in dry plant communities and low densities in wet communities. However, nematode developmental success was positively related to soil moisture content, and was highest in the wetter sites. Thus, by avoiding dry areas with high dropping densities, reindeer would tend to feed in wetter areas where nematodes thrive. Therefore, dung density may be an unreliable predictor of the risk of infection. The absence of a strong relationship between an individual's infection level and its diet might be due to the unpredictability of pasture infection level.
我们测试了斯瓦尔巴德驯鹿（Rangifer tarandus platyrhynchus）是否通过避开粪便密度高的区域来将胃肠道线虫感染风险降至最低。该实验在夏季首选的觅食栖息地进行。通过测量七个植物群落中粪便的分布情况，以及两个土壤湿度不同的植物群落中线虫的发育成功率，来确定驯鹿是否会根据植物群落中粪便污染水平来评估感染风险。我们探究了个体驯鹿胃肠道线虫感染水平的差异是否与其饮食有关。驯鹿避开了粪便污染增加的牧场，从而有可能降低感染毛圆线虫的风险。粪便密度与土壤湿度呈负相关，干燥植物群落中的粪便密度高，而潮湿群落中的密度低。然而，线虫的发育成功率与土壤湿度呈正相关，在较潮湿的地点最高。因此，通过避开粪便密度高的干燥区域，驯鹿倾向于在更潮湿、线虫大量繁殖的区域觅食。所以，粪便密度可能不是感染风险的可靠预测指标。个体感染水平与其饮食之间缺乏紧密关系，可能是由于牧场感染水平的不可预测性。
