Faculty of Veterinary Medicine, University of Calgary, 3280 University Drive, NW, Calgary, AB, T2N 1N4, Canada.
Environment and Natural Resources, Government of the Northwest Territories, Yellowknife, NT, X1A 1Y3, Canada.
Sci Rep. 2024 Jul 25;14(1):17133. doi: 10.1038/s41598-024-67904-y.
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.
寄生虫会直接影响有蹄类动物的健康，在野生动物中，这些影响可能与其他压力源（如有限的营养资源）同时发生。在北极地区，麝香牛（Ovibos moschatus）生活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繁殖。当加拿大班克斯岛的麝香牛数量和密度达到峰值时，我们研究了胃肠道线虫对 141 头麝香牛的身体状况和繁殖状况的影响。利用偏最小二乘路径建模方法，我们发现，成年线虫数量高与身体状况差有关，寄生虫数量高与雌性繁殖有关，包括通过身体状况产生的间接影响（n=87）。这些发现表明，个体将能量储备优先用于繁殖而不是寄生虫防御。2003 年秋季，一场严重的结冰事件限制了对饲料的获取，导致麝香牛越冬死亡率高，数量骤减。通过寄生虫感染对身体状况和繁殖的直接和间接成本，寄生虫的高丰度可能导致了这种极端天气事件的发生。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，并预测环境和种群之间的相互作用。
