INRE, ISP, Université de Tours, Nouzilly, France.
IHAP, INRAE, ENVT, Université de Toulouse, Toulouse, France.
Parasit Vectors. 2023 Feb 11;16(1):64. doi: 10.1186/s13071-022-05645-5.
Equine strongyles encompass more than 64 species of nematode worms that are responsible for growth retardation and the death of animals. The factors underpinning variation in the structure of the equine strongyle community remain unknown.
Using horse-based strongyle community data collected after horse deworming (48 horses in Poland, 197 horses in Ukraine), we regressed species richness and the Gini-Simpson index upon the horse's age, faecal egg count, sex and operation of origin. Using the Ukrainian observations, we applied a hierarchical diversity partitioning framework to estimate how communities were remodelled across operations, age groups and horses. Lastly, strongyle species counts collected after necropsy (46 horses in France, 150 in Australia) were considered for analysis of their co-occurrences across intestinal compartments using a joint species distribution modelling approach.
First, inter-operation variation accounted for > 45% of the variance in species richness or the Gini-Simpson index (which relates to species dominance in communities). Species richness decreased with horse's age (P = 0.01) and showed a mild increase with parasite egg excretion (P < 0.1), but the Gini-Simpson index was neither associated with parasite egg excretion (P = 0.8) nor with horse age (P = 0.37). Second, within-host diversity represented half of the overall diversity across Ukrainian operations. While this is expected to erase species diversity across communities, community dissimilarity between horse age classes was the second most important contributor to overall diversity (25.8%). Third, analysis of species abundance data quantified at necropsy defined a network of positive co-occurrences between the four most prevalent strongyle genera. This pattern was common to necropsies performed in France and Australia.
Taken together, these results show a pattern of β-diversity maintenance across age classes combined with positive co-occurrences that might be grounded by priority effects between the major species.
马胃线虫包含超过 64 种线虫，它们会导致动物生长迟缓甚至死亡。目前尚不清楚支撑马胃线虫群落结构变化的因素。
我们根据马驱虫后的马胃线虫群落数据（波兰 48 匹马，乌克兰 197 匹马），回归物种丰富度和基尼-辛普森指数与马的年龄、粪便卵计数、性别和起源操作之间的关系。利用乌克兰的观测结果，我们应用了一个层次多样性划分框架，以估计在操作、年龄组和马之间群落是如何重塑的。最后，我们对法国 46 匹马和澳大利亚 150 匹马的剖检后收集的胃线虫物种计数进行了分析，使用联合物种分布模型方法分析了它们在肠道不同部位的共同出现情况。
首先，操作间的变异解释了物种丰富度或基尼-辛普森指数（与群落中的物种优势有关）变异的 45%以上（P = 0.01）。物种丰富度随马的年龄而降低（P = 0.01），且与寄生虫卵排泄呈轻度增加（P < 0.1），但基尼-辛普森指数与寄生虫卵排泄（P = 0.8）或马的年龄（P = 0.37）均无关联。其次，宿主内多样性占乌克兰操作间整体多样性的一半。虽然这预计会消除群落间的物种多样性，但马年龄类群之间的群落差异是整体多样性的第二大贡献者（25.8%）。第三，对剖检时定量的物种丰度数据的分析确定了四个最常见的胃线虫属之间存在正共现关系的网络。这种模式在法国和澳大利亚的剖检中都是常见的。
综上所述，这些结果显示了跨年龄类群的β多样性维持模式，加上可能由主要物种之间的优先效应所决定的正共现模式。
