Department of Biological Sciences, Virginia Polytechnic Institute, Blacksburg, VA 24061, USA.
Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA.
Biol Lett. 2023 Mar;19(3):20220574. doi: 10.1098/rsbl.2022.0574. Epub 2023 Mar 1.
Understanding host persistence with emerging pathogens is essential for conserving populations. Hosts may initially survive pathogen invasions through pre-adaptive mechanisms. However, whether pre-adaptive traits are directionally selected to increase in frequency depends on the heritability and environmental dependence of the trait and the costs of trait maintenance. Body condition is likely an important pre-adaptive mechanism aiding in host survival, although can be seasonally variable in wildlife hosts. We used data collected over 7 years on bat body mass, infection and survival to determine the role of host body condition during the invasion and establishment of the emerging disease, white-nose syndrome. We found that when the pathogen first invaded, bats with higher body mass were more likely to survive, but this effect dissipated following the initial epizootic. We also found that heavier bats lost more weight overwinter, but fat loss depended on infection severity. Lastly, we found mixed support that bat mass increased in the population after pathogen arrival; high annual plasticity in individual bat masses may have reduced the potential for directional selection. Overall, our results suggest that some factors that contribute to host survival during pathogen invasion may diminish over time and are potentially replaced by other host adaptations.
了解宿主对新兴病原体的持久性对于保护种群至关重要。宿主最初可能通过预先适应机制在病原体入侵时存活下来。然而，预先适应特征是否会朝着增加频率的方向被选择，取决于特征的遗传力和环境依赖性以及特征维持的成本。身体状况可能是帮助宿主存活的一个重要的预先适应机制，尽管在野生动物宿主中可能会随季节而变化。我们使用了 7 年来收集的蝙蝠体重、感染和生存数据，以确定在新兴疾病——白鼻综合征的入侵和建立过程中宿主身体状况的作用。我们发现，当病原体首次入侵时，体重较高的蝙蝠更有可能存活，但这种影响在最初的疫病后消失了。我们还发现，较重的蝙蝠在冬季会失去更多的体重，但脂肪损失取决于感染的严重程度。最后，我们发现有混合证据表明，在病原体到达后，蝙蝠数量有所增加；个体蝙蝠体重的高年度可塑性可能降低了定向选择的潜力。总的来说，我们的研究结果表明，在病原体入侵期间有助于宿主存活的一些因素可能会随着时间的推移而减少，并可能被其他宿主适应性所取代。
