PDF(Pubmed)
Abstract：
Parasites negatively affect the fitness of ungulate hosts directly, and in wild ungulates, these effects may be synzootic with other stressors, such as limited nutritional resources. In the Arctic, muskoxen (Ovibos moschatus) occur in a highly seasonal environment and must rely on finite energetic resources for survival and productivity. We investigated the costs of gastrointestinal nematodes on the body condition and reproductive status of 141 muskoxen, on Banks Island, Canada, when the population was at a peak in numbers and density. Using a Partial Least Squares Path Modelling approach, we found that high adult nematode abundance was associated with lower body condition, and high parasite abundance was associated with female reproduction including the indirect effect through on body condition (n = 87). These findings suggest that individuals prioritize energetic reserves for reproduction over parasite defence. In fall 2003, a severe icing event that restricted access to forage was associated with high overwinter mortality of muskoxen and a population crash. Through direct and indirect costs of parasite infection on body condition and reproduction, the high abundance of parasites may have contributed to the effects of this extreme weather event. Understanding the mechanisms in which parasites impact fitness can help explain the ecological drivers of ungulate populations and predict the interactions between the environment and populations.
摘要：
寄生虫会直接影响有蹄类动物宿主的适应性，在野生有蹄类动物中，这些影响可能与其他压力源共生，比如有限的营养资源。在北极,Muskoxen（Ovibosmoschatus）发生在高度季节性的环境中，必须依靠有限的能量资源来生存和生产力。我们调查了胃肠道线虫对141麝香的身体状况和生殖状况的成本，在班克斯岛,加拿大,当人口数量和密度达到峰值时。使用偏最小二乘路径建模方法，我们发现高的成虫线虫丰度与下体状态有关,高寄生虫丰度与女性生殖有关，包括对身体状况的间接影响（n=87）。这些发现表明，个体优先考虑用于繁殖的能量储备而不是寄生虫防御。2003年秋季，严重的结冰事件限制了饲草的使用，这与麝牛过冬死亡率高和人口崩溃有关。通过寄生虫感染对身体状况和繁殖的直接和间接成本，大量的寄生虫可能是造成这种极端天气事件影响的原因。了解寄生虫影响健康的机制可以帮助解释有蹄类动物种群的生态驱动因素，并预测环境与种群之间的相互作用。
