Lynsdale Carly L, Seltmann Martin W, Mon Nay Oo, Aung Htoo Htoo, Nyein UKyaw, Htut Win, Lahdenperä Mirkka, Lummaa Virpi
Natural Resources Institute, Helsinki, Finland.
Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
Behav Ecol Sociobiol. 2022;76(7):87. doi: 10.1007/s00265-022-03192-8. Epub 2022 Jun 24.
Frequent social interactions, proximity to conspecifics, and group density are main drivers of infections and parasite transmissions. However, recent theoretical and empirical studies suggest that the health benefits of sociality and group living can outweigh the costs of infection and help social individuals fight infections or increase their infection-related tolerance level. Here, we combine the advantage of studying artificially created social work groups with different demographic compositions with free-range feeding and social behaviours in semi-captive Asian elephants (), employed in timber logging in Myanmar. We examine the link between gastro-intestinal nematode load (strongyles and spp), estimated by faecal egg counts, and three different aspects of an elephant's social world: individual solitary behaviour, work group size, and work group sex ratio. Controlling for sex, age, origin, time since last deworming treatment, year, human sampler bias, and individual identity, we found that infection by nematodes ranged from 0 to 2720 eggs/g between and within 26 male and 45 female elephants over the 4-year study period. However, such variation was not linked to any investigated measures of sociality in either males or females. Our findings highlight the need for finer-scale studies, establishing how sociality is limited by, mitigates, or protects against infection in different ecological contexts, to fully understand the mechanisms underlying these pathways.
Being social involves not only benefits, such as improved health, but also costs, including increased risk of parasitism and infectious disease. We studied the relationship between and three different sociality measures-solitary behaviour, group size, and the proportion of females to males within a group-and infection by gut nematodes (roundworms), using a unique study system of semi-captive working Asian elephants. Our system allows for observing how infection is linked to sociality measures across different social frameworks. We found that none of our social measures was associated with nematode infection in the studied elephants. Our results therefore suggest that here infection is not a large cost to group living, that it can be alleviated by the benefits of increased sociality, or that there are weak infection-sociality associations present which could not be captured and thus require finer-scale measures than those studied here. Overall, more studies are needed from a diverse range of systems that investigate specific aspects of social infection dynamics.
The online version contains supplementary material available at 10.1007/s00265-022-03192-8.
频繁的社交互动、与同种个体的接近程度以及群体密度是感染和寄生虫传播的主要驱动因素。然而，最近的理论和实证研究表明，社交和群体生活对健康的益处可能超过感染成本，并有助于社交个体抵抗感染或提高其对感染的耐受水平。在这里，我们结合了研究具有不同人口构成的人工创建的社会工作群体的优势，以及半圈养亚洲象（缅甸用于木材采伐）的自由放养和社交行为。我们研究了通过粪便虫卵计数估算的胃肠道线虫负荷（圆线虫和其他线虫种类）与大象社会世界的三个不同方面之间的联系：个体独居行为、工作群体规模和工作群体性别比例。在控制了性别、年龄、来源、上次驱虫治疗后的时间、年份、人类采样偏差和个体身份后，我们发现在为期4年的研究期间，26头雄性大象和45头雌性大象体内线虫感染情况各不相同，每克粪便中的虫卵数在0至2720个之间。然而，这种差异与雄性或雌性大象的任何一项所研究的社交指标均无关联。我们的研究结果强调需要进行更精细的研究，以确定在不同生态环境中社交如何受到感染的限制、减轻感染或预防感染，从而全面了解这些途径背后的机制。
社交不仅带来诸如健康改善等益处，还存在成本，包括寄生虫感染和传染病风险增加。我们使用半圈养工作亚洲象这一独特研究系统，研究了肠道线虫（蛔虫）感染与三种不同社交指标——独居行为、群体规模以及群体内雌性与雄性比例——之间的关系。我们的系统能够观察到在不同社会框架下感染与社交指标之间的联系。我们发现，在所研究的大象中，我们的任何一项社交指标均与线虫感染无关。因此，我们的研究结果表明，在这里感染并非群体生活的巨大成本，感染可通过社交增加带来的益处得到缓解，或者存在微弱的感染 - 社交关联但未被捕捉到，因此需要比本研究中更精细的测量方法。总体而言，需要从更多不同系统开展研究，以调查社交感染动态的具体方面。
在线版本包含可在10.1007/s00265 - 022 - 03192 - 8获取的补充材料。
