Longitudinal dynamics of co-infecting gastrointestinal parasites in a wild sheep population.
Longitudinal dynamics of co-infecting gastrointestinal parasites in a wild sheep population.
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DOI：
10.1017/s0031182021001980
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发表时间：
2022-02-03
期刊：
影响因子：
2.4
通讯作者：
Kenyon, Fiona
中科院分区：
文献类型：
--
作者：
Sweeny, Amy R.;Corripio-Miyar, Yolanda;Bal, Xavier;Hayward, Adam D.;Pilkington, Jill G.;McNeilly, Tom N.;Nussey, Daniel H.;Kenyon, Fiona
关键词：
感染的年内变化是自然种群普遍存在的特征，但由环境、寄生虫和宿主因素的复杂相互作用决定。与此同时，混合感染在野外是常态。因此，共感染寄生虫的纵向动态可能会因多个寄生虫之间的协变而进一步复杂化。在这里，我们使用重复收集的粪便寄生虫卵和卵囊计数从单独标记的野生大豆羊来调查六个胃肠道寄生虫组的季节动态。春季和夏季的流行率和丰度有较高的趋势，羔羊的丰度高于成年羊。我们发现，高度流行的粗线虫数量在一年内的变化取决于成年繁殖状况，与雄性和不育的母羊相比，繁殖母羊具有明显的动态。对于类似流行的球虫，我们发现卵囊计数在春季达到总体峰值，但在雄性、不育和怀孕母羊之间没有差异。使用多变量混合效应模型，我们进一步表明，强直球虫数和球虫数之间的明显正相关是由这两个数的短期个体内变化驱动的，而不是长期的个体间协变。总体而言，这些结果表明，季节性在人口和寄生虫群体中有所不同，并突出了随着时间的推移研究联合感染动态的价值。
Within-year variation in infection is a ubiquitous feature of natural populations, but is determined by a complex interplay of environmental, parasitological and host factors. At the same time, co-infection is the norm in the wild. Longitudinal dynamics of co-infecting parasites may therefore be further complicated by covariation across multiple parasites. Here, we used fecal parasite egg and oocyst counts collected repeatedly from individually marked wild Soay sheep to investigate seasonal dynamics of six gastrointestinal parasite groups. Prevalence and abundance tended to be higher in spring and summer, and abundance was higher in lambs compared to adults. We found that within-year variation in highly prevalent strongyle nematode counts was dependent on adult reproductive status, where reproductive ewes had distinct dynamics compared to males and barren ewes. For similarly prevalent coccidia we found an overall peak in oocyst counts in spring but no differences among males, barren and pregnant ewes. Using multivariate mixed-effects models, we further show that apparent positive correlation between strongyle and coccidia counts was driven by short-term within-individual changes in both counts rather than long-term among-individual covariation. Overall, these results demonstrate that seasonality varies across demographic and parasite groups and highlight the value of investigating co-infection dynamics over time.