Data from: Local demographic and epidemiological patterns in the Linum marginale – Melampsora lini association – a multi-year study

1.Many theoretical and empirical studies operate from an assumption that pathogens have a significant influence on the fecundity and lifespan of their host species. However, there is surprisingly little data investigating the long-term fitness impacts and genetic consequences that arise from pathogen infection in natural populations. Here, we address this gap through the analysis of a dataset investigating the local population dynamics of a native host plant (Linum marginale) and an associated rust pathogen (Melampsora lini) across 12 years.

2.To investigate patterns of disease prevalence and severity and track effects on host fecundity and demography we conducted censuses on an annual basis at a single site. Annual M. lini infection prevalence ranged from 0% to 99%. Severe epidemics occurred in 3-4 year cycles causing high overwintering mortality and subsequent changes in the relative abundance of different host phenotypes. Host population size oscillated in response to epidemics and declined towards the end of the observation period. Changes in host numbers were found to affect disease severity but not infection prevalence.

3.Melampsora lini infection increased L. marginale fecundity; the infected plants produced three fold more seed capsules on average than uninfected plants (13.3 vs 4.3 seed capsules per plant).

4.To investigate how variation in environmental conditions affects epidemiology and host demography, we identified climatic factors affecting host growth, overwintering, and disease severity. Winter (June) rainfall increased host overwintering success and summer (December) rainfall favoured host growth. The progress of Melampsora lini disease epidemics benefited from optimal temperatures in February and suffered from rainfall in January.

5.We further examined links between the genetic structure of the pathogen population and disease dynamics. There was a positive correlation between mean pathogen infectivity (as measured across a host differential set) and the severity of disease epidemics.

6.Synthesis. Our results provide new insights into local drivers and consequences of pathogen epidemiology in natural populations. Melampsora lini infection can have profound consequences on the phenotype, demography and population structure of Linum marginale by increasing host fecundity, overwinter mortality and disease resistance.

1. 诸多理论与实证研究均基于“病原体对宿主物种的繁殖力与寿命具有显著影响”这一假设展开。然而，目前针对自然种群中病原体感染所引发的长期适合度效应与遗传后果的调查数据却极为匮乏。本研究通过分析一项长达12年的数据集，填补了这一研究空白，该数据集针对本土宿主植物边缘亚麻（Linum marginale）及其伴生锈病病原菌亚麻栅锈菌（Melampsora lini）的局域种群动态展开了长期监测。
2. 为探究病害流行率与严重程度的变化模式，并追踪其对宿主繁殖力与种群动态的影响，本研究在单一样地开展了年度普查。亚麻栅锈菌的年度感染率介于0%至99%之间。每3至4年便会爆发一次严重锈病流行，该流行事件会引发极高的宿主越冬死亡率，并随之改变不同宿主表型的相对丰度。宿主种群规模随病害流行呈现周期性波动，并在观测期后期出现下降趋势。研究发现，宿主种群数量的变化会影响病害严重程度，但不会改变感染率。
3. 亚麻栅锈菌感染可提升边缘亚麻的繁殖力：受感染植株的平均结蒴数为未感染植株的3倍（单株平均结蒴数分别为13.3与4.3）。
4. 为探究环境条件的变异如何影响病害流行与宿主种群动态，本研究鉴定出了影响宿主生长、越冬存活及病害严重程度的气候因子。该研究样地的冬季（6月）降雨量提升了宿主的越冬存活率，夏季（12月）降雨量则有利于宿主生长。亚麻栅锈菌病害的流行进程得益于2月的适宜温度，却会因1月的降雨而受到抑制。
5. 本研究进一步探究了病原菌种群的遗传结构与病害动态之间的关联。结果显示，病原菌的平均侵染力（通过宿主鉴别寄主套装测定）与病害流行严重程度呈正相关。
6. 研究总结：本研究结果为揭示自然种群中病原体流行病学的局域驱动因子与效应提供了新的认知。亚麻栅锈菌的感染可通过提升宿主繁殖力、加剧越冬死亡率与增强病害抗性，对边缘亚麻的表型、种群动态及种群结构产生深远影响。